An analysis of the cellular localization of cytochrome oxidase in the lateral geniculate nucleus of the adult cat

The distribution of cytochrome oxidase (C.O.) was examined in the normal adult cat lateral geniculate nucleus at the cellular and electron-microscopic levels. The darker reactivity of the X- and/or Y-receptive laminae (A, A1, magnocellular lamina C [Cm], and medial interlaminar nucleus [MIN]) compared with the lightly reactive W-receptive parvicellular lamina C (Cp) indicates that there are pathway-specific histochemical differences in the visual system of the cat. At the cellular level, darkly reactive large cells in the lateral geniculate nucleus (LGN) closely resemble class 1, Y-cells, in relative size and distribution, thus indicating that C.O. histochemistry may be used as a functional marker for these cells. Perigeniculate neurons are also darkly reactive. Neuronal classes 2, 4, and 3 (presumed X-cells, W-cells, and/or interneurons) have moderate to lightly reactive perikarya. The darkly reactive neuronal classes tend to receive relatively stronger proximal excitatory synaptic input than do the less reactive neuronal classes. Since all neuronal classes appeared to have darkly (or moderately) reactive dendrites, C.O. reactivity must differ between dendrite and soma of some neuronal classes. At the electron-microscopic level, distinct components of the neuropil tend to have specific levels of C.O. reactivity. The predominance of darkly reactive mitochondria in dendrites indicates that dendrites are metabolically very active. RLD and may F's, but few large axon terminals with round vesicles (RL) or small axon terminals with round vesicles (RS) profiles are darkly reactive, implying that specific classes of presynaptic structures are more active than others. Thus C.O. histochemistry may be useful for distinguishing not only functionally active neuronal classes such as Y-cells and perigeniculate (PG) neurons from less active neuronal classes, but also functionally more or less active parts of the same neuron including its dendrites, axons, and/or axon terminals.     

Quantitative analysis of neuronal nitric oxide synthase-immunoreactive neurons in the mouse hippocampus with optical disector.

A detailed quantitative analysis of immunocytochemically identified nonprincipal neurons containing neuronal nitric oxide synthase (nNOS) was performed on the mouse hippocampus, with particular reference to the dorsoventral gradient. The present study applied two variations of a stereologic technique, the optical disector--one that used confocal laser-scanning microscope optical sections to examine colocalization of nNOS and glutamic acid decarboxylase 67 (GAD67), and the other that used conventional thick sections to examine numerical densities (NDs) and cell sizes of nNOS-immunoreactive (IR) neurons. Colocalization analysis indicated that practically all nNOS-IR neurons (97.6%) were GAD67-IR, whereas a part of the GAD67-IR neurons (about 30%) were nNOS-IR in the whole hippocampus at both dorsal and ventral levels. The percentages of GAD67-IR neurons containing nNOS were higher in the dentate gyrus (DG, about 50%), and lower in the Ammon's horn (about 20%). Laminar analysis revealed that the majority of GAD67-IR neurons contained nNOS in the stratum lacunosum-moleculare of the CA3 region (about 60%) and in the molecular layer of the DG (about 80%). The NDs of nNOS-IR neurons in the whole hippocampus showed a dorsoventral gradient, which increased from dorsal (1.6 x 10(3)/mm3) to ventral (2.2 x 10(3)/mm3) levels. The NDs were relatively higher in the principal cell layers, where about 40% of nNOS-IR neurons were situated both in the Ammon's horn and DG. The mean cell sizes of nNOS-IR neurons showed no remarkable laminar differences or dorsoventral gradient in the Ammon's horn, but they were extensively larger in the hilus of the DG than in other layers. These results indicate that nNOS-IR neurons in the mouse hippocampus represent a subpopulation of gamma-aminobutyric acid (GABA)ergic neurons and suggest that the laminar distributions of nNOS-IR neurons related to possible functional heterogeneity of GABAergic neurons in each hippocampal layer.     

Substance P receptors in the human spinal cord: decrease in amyotrophic lateral sclerosis

The distribution of substance P receptors was examined by autoradiography at all levels of the human postmortem spinal cord using the ligand [125I]Bolton-Hunter substance P. Adjacent sections were used to localize substance P-like immunoreactivity by a radioimmunohistochemical technique. In the control spinal cord substance P-like immunoreactivity was found to be highly concentrated in the superficial layers of the dorsal horn, intermediolateral cell columns and lamina X, while lower levels of immunoreactivity were observed in other areas of the grey matter of the spinal cord. In contrast, high densities of substance P binding sites were localized not only to the substantia gelatinosa of the dorsal horn but also to other regions of the grey matter of the spinal cord, particularly in the area of the preganglionic sympathetic neurons in the intermediolateral cell column and in the region of the somatic motor neurons of the ventral horn. In 5 cases of amyotrophic lateral sclerosis we found a marked reduction of substance P binding, especially in the ventral horn associated with the loss of motor neurons. These results suggest a postsynaptic localization of substance P receptors to the motor neurons of the ventral horn in the human spinal cord and a role for substance P in the function of motor neurons.     

Relationship between synaptogenesis and cytochrome oxidase activity in Purkinje cells of the developing rat cerebellum

In the adult CNS, the level of oxidative metabolism, as indicated by cytochrome oxidase cytochemistry, can be correlated with the level of neuronal activity. Specifically, heightened cytochrome oxidase activity in post-synaptic neurons can often be correlated with a greater proportion of excitatory inputs, whereas inhibitory inputs often result in a low level of cytochrome oxidase activity. This relationship has not been explored in developing neurons. To this end, cytochrome oxidase cytochemistry was used to compare the levels of oxidative metabolism in rat cerebellar Purkinje cells at various stages of their development. The results indicated that the level of cytochrome oxidase activity in Purkinje cell somata and dendrites correlated closely with the type of synaptic input (excitatory or inhibitory) received by the different segments of the cell. When the cell somata received predominantly excitatory input from climbing fibers, their mitochondria were evenly distributed between the three reactive classes: dark, moderate, and lightly reactive for cytochrome oxidase. When the cell somata received predominantly inhibitory input from basket cell terminals, lightly reactive mitochondria were the prevailing type. Further support for the correlation of excitatory synaptic input with high levels of cytochrome oxidase activity was found in the quantitation of mitochondria within Purkinje cell dendrites. These dendrites received largely excitatory input at all ages and had high levels of cytochrome oxidase activity throughout development and adulthood. There was also a relationship between the level of cytochrome oxidase activity and mitochondrial size within Purkinje cell somata and dendrites from birth to adult. Darkly reactive mitochondria had a greater mean area than moderately reactive mitochondria which, in turn, had a greater mean area than lightly reactive mitochondria. In addition, the packing density of mitochondria within the cytoplasm varied with age in both somata and dendrites. In the somata, the packing density peaked at postnatal day 7, and in dendrites, the peak occurred at postnatal day 10. These data indicate that in a developing system, postsynaptic neurons respond to sequential excitatory and inhibitory inputs by sequential heightening and lowering of their energy metabolism. Thus, cytochrome oxidase activity in a postsynaptic neuron can be correlated with the predominant type of synaptic input that it receives.     

Localizing spinal-cord-projecting neurons in adult albino rats

Cytochrome oxidase activity was examined in the striate cortex (area 17) of squirrel monkeys at both the light and ultrastructural levels. Two prominent bands of reactivity were found in 4A and 4C with intermittent puffs of cytochrome oxidase reactivity in laminae 2 and 3. These puffs, spaced 0.5 mm apart, were in register with intermittent concentrations of activity in laminae 4B, 5, and 6. A thin band of reactivity was observed in lamina 1. The upper portion of 4C beta was less reactive than 4C alpha or the lower portion of 4C beta. Reactive neurons included stellate cells in all laminae and pyramidal cells in laminae 2 through 4B, 5, and 6. A row of large reactive pyramidal cells was observed in upper lamina 6. More reactive neurons were found in the puffs (laminae 2 and 3) than were observed in interpuff regions, and the reactive neurons were significantly larger than the nonreactive neurons. Reactive neurons contained two to three times as many reactive mitochondria as did the nonreactive neurons and often had indented nuclei. Based on the number of darkly or highly reactive, moderately reactive and lightly reactive mitochondria, puff regions were significantly different from nonpuff regions; there were approximately two times as many darkly reactive mitochondria in puff regions as compared to a similar nonpuff area. The majority of mitochondria (32% in puff; 44% in nonpuff) were found to reside in the dendritic profiles, which also contained the majority of highly reactive mitochondria. In a separate analysis, the total area of highly reactive mitochondria within puff regions was found to be twice the total area of highly reactive mitochondria in a comparable nonpuff region. An analysis of synapses showed that there were more asymmetrical synapses in both puff and nonpuff regions (55% and 54%, respectively) than symmetrical ones (45% in puff and 46% in nonpuff). There was an increase in mitochondrial reactivity in both asymmetrical and symmetrical synapses in the puff areas; however, the increased reactivity within asymmetrical terminals was significantly greater than that within symmetrical ones. Several somatodendritic synapses were observed and they were all of the symmetrical variety. Axospinous contacts were primarily of the asymmetrical type; however, symmetrical axospinous synapses were observed and were typically seen in association with an asymmetrical synapse. It was concluded that cytochrome oxidase activity is localized primarily within the dendritic profiles in both puff and nonpuff regions.(ABSTRACT TRUNCATED AT 400 WORDS)     

The localization of cytochrome oxidase in the LGN and striate cortex of postnatal kittens

The distribution of cytochrome oxidase (C.O.) was examined in the lateral geniculate nucleus of the kitten during the first postnatal month and compared with the adult pattern. During the first week, most of the C.O. was localized within the perikarya of geniculate neurons. Perigeniculate neurons had darkly reactive dendrites as well as perikaya. A population of relatively large, darkly reactive neurons became distinguishable around the end of the first week, as the level of reactivity diminished to moderate-to-light within most medium and small neurons. On the basis of their relative size and pattern of distribution, most of the darkly reactive neurons are likely to represent ones that will later have class 1 morphology and develop Y receptive field properties. These cells normally undergo rapid growth earlier, and their growth is more adversely affected by early short-term monocular suture than other classes of less reactive geniculate neurons. Thus, in the LGN of developing kitten, C.O. histochemistry may be used as a functional marker for future class 1 Y-cells. The reactivity of the neuropil gradually increases as synapses with dendrites mature. At the electronmicroscopic level the increased reactivity of the neuropil is due mainly to an increase in the number of reactive mitochondria localized within the growing dendrites. In the developing striate cortex of postnatal kittens dark reactivity is localized in the outer part of layer II for the first 2 weeks and then disappears. Dark reactivity gradually increases in layer IV after the third week. The changes in C.O. reactivity accompany pathway-specific physiological and anatomical changes that occur during early postnatal development.     

Nitric oxide synthase expression and cell changes in dorsal root ganglia and spinal dorsal horn of developing and adult Rana esculenta indicate a role of nitric oxide in limb metamorphosis

Metamorphosis of amphibians requires reconfiguration of sensory and locomotor neural networks. In view of such plastic changes and implications of nitric oxide (NO) in neural developmental shaping, we examined via histochemistry and immunohistochemistry its synthetic enzyme nitric oxide synthase (NOS) in dorsal root ganglia (DRGs) and dorsal horn of the developing and adult frog Rana esculenta. In limb DRGs, NOS positivity was first and selectively detected just before limb bud appearance, increased during metamorphosis, and was then down-regulated. In adulthood, NOS was expressed in some DRG neurons at all segmental levels. Similar features were detected in the dorsal horn neuropil. In limb DRGs, cell counts in Nissl-stained sections revealed a twofold increase of differentiated neurons during metamorphosis and an additional twofold increase in adulthood. Perikaryal sizes in limb DRGs did not vary during metamorphosis but increased and were more heterogeneous in the adult frog, probably reflecting adaptation to body size. NOS and cell changes during metamorphosis were much less marked in DRGs at other levels. Carbocyanine tracing documented selective labeling of NOS-expressing hindlimb DRG neurons from the spinal nerve at the time of initiation of hindlimb movements. The findings show that, in limb DRG neurons, NOS parallels cell differentiation and limb development during metamorphosis. The data also provide evidence of NOS expression in DRG cells innervating the hindlimbs when sensorimotor circuits become functionally mature. This study indicates a key role of NO production in the maturation of sensory functions that subserves in amphibians the transition from swimming to tetrapod locomotion.     

GABA- and glycine-immunoreactive neurons in the spinal cord of the carp,Cyprinus carpio

γ-Aminobutyric acid (GABA) and glycine are the two main inhibitory transmitter amino acids in the central nervous system of vertebrates. The distribution of cells containing GABA and glycine in the carp spinal cord was examined by using specific antisera raised against the two amino acids conjugated to bovine serum albumin. The immunoreaction on serial paraffin sections was visualized by a streptavidin-biotin method. Both antisera gave highly specific labellings of cells. At least three types of GABA-immunoreactive cells were found. They were small cells in the dorsal grey matter, various sized cells in the central and ventral grey, and some ependymal cells contacting the central canal. In addition, very small cells and neuropil structures in the dorsal horn were strongly immunoreactive to the GABA serum. Certain cells in the ventral horn have moderate numbers of labelled synaptic boutons on the perikarya, but very few GABA-labelled terminals were found on putative motoneurons. The immunoreactive ependymal cells appeared to have a ventrolaterally directed axon. The glycine antiserum labelled small and intermediate cells in the dorsal grey, large, elongated cells in the median region, and varying sized cell sin the ventral grey. The numbers and density of immunoreactive cells and neuropil strucures in the ventral horn were fewer and lower than in GABA-stained sections. The median large cells had a thick venrolateral process. The ventral intermediate cells were often found near putative motoneurons. Labelled synaptic boutons were present on most ventral cells including putative motoneurons and interneurons. Abundant distribution of cells immunoreactive to both antisera suggest important roles of both GABA and glycine as neurotransmitters for controlling swimming movements in teleosts. © 1993 Wiley-Liss, Inc.     

Double labeling of GABA and cytochrome oxidase in the macaque visual cortex: Quantitative EM analysis

In the primate striate cortex, cytochrome oxidase (CO)-rich puffs differ from CO-poor interpuffs in their metabolic levels and physiological properties. The neurochemical basis for their metabolic and physiological differences is not well understood. The goal of the present study was to examine the relationship between the distribution of gamma aminobutyric acid (GABA)/non-GABA synapses and CO levels in postsynaptic neuronal profiles and to determine whether or not a difference existed between puffs and interpuffs. By combining CO histochemistry and postembedding GABA immunocytochemistry on the same ultrathin sections, the simultaneous distribution of the two markers in individual neuronal profiles was quantitatively analyzed. In both puffs and interpuffs, GABA-immunoreactive (GABA-IR) neurons were the only cell type that received both non-GABA-IR (presumed excitatory) and GABA-IR (presumed inhibitory) axosomatic synapses, and they had three times as many mitochondria darkly reactive for CO than non-GABA-IR neurons, which received only GABA-IR axosomatic synapses. GABA-IR neurons and terminals in puffs had a larger mean size, about twice as many darkly reactive mitochondria, and a higher ratio of non-GABA-IR to GABA-IR axosomatic synapses than those in interpuffs (2.3:1 vs. 1.6:1; P < 0.01). There were significantly more synapses of both non-GABA-IR and GABA-IR types in the neuropil of puffs than of interpuffs; however, the ratio of non-GABA-IR to GABA-IR synapses was significantly higher in puffs (2.86:1) than in interpuffs (2.08:1; P < 0.01). Our results are consistent with the hypothesis that the level of oxidative metabolism in postsynaptic neurons and neuronal processes is tightly governed by the strength and proportion of excitatory over inhibitory synapses. Thus, the present results suggest that (1) GABA-IR neurons in the macaque striate cortex have a higher level of oxidative metabolism than non-GABA ones because their somata receive direct excitatory synapses and their terminals are more tonically active; (2) the higher proportion of presumed excitatory synapses in puffs imposes a greater energy demand there than in interpuffs; and (3) excitatory synaptic activity may be more prominent in puffs than in interpuffs because puffs receive a greater proportion of excitatory synapses from multiple sources including the lateral geniculate nucleus, which is not known to project to the interpuffs. © 1995 Wiley-Liss, Inc.     

Central projections from the skin of the hand in squirrel monkeys.

Central termination patterns of afferents from the hands of squirrel monkeys were studied after subdermal injections of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) or cholera toxin subunit B conjugated to HRP (BHRP). WGA-HRP more effectively labeled axons terminating in the superficial dorsal horn of the spinal cord, while BHRP more effectively labeled axons terminating in the deeper layers. Injections of both tracers, when restricted to parts of glabrous digits, palm, or dorsal hand, revealed somatotopic patterns in the spinal cord and pars rotunda of the cuneate nucleus that were, in some respects, similar and, in other respects, quite different from those previously reported for macaque monkey (Florence et al., J. Comp. Neurol. 286:48-70, '89). As in macaques, injections in digits 1-5 produced a rostrocaudal sequence of foci of terminations in the cervical spinal cord. However, inputs from the palm were located medial to those from the digits, whereas the palm is represented lateral to the digits in macaque monkeys. Since inputs from the palm is also medial in the dorsal horn in cats (Nyberg and Blomqvist, J. Comp. Neurol. 242:28-39, '85), the condition in squirrel monkeys may be similar to the generalized state. In the cuneate nucleus, single injections in the hand produced dense label in the pars rotunda, and sparse label in the rostral and caudal poles. As in macaque monkeys, inputs from specific parts of the hand related to rostrocaudal clusters of cells that are cytochrome oxidase dense. The representation of the digits differed from macaques in that the digits were represented dorsal to the palm, rather that ventral to the palm as in macaques. Again, comparisons with cats suggest that squirrel monkeys have the more generalized pattern. Finally, inputs from the hair, dorsal surfaces of the digits terminated on the same clusters as the inputs from the glabrous, ventral surfaces, apparently overlapping somewhat. The proximity of these terminations from dorsal and ventral surfaces of the digits may be related to observations that cortical representations of the glabrous surfaces of digits become responsive to dorsal surfaces of the same digits when inputs from glabrous skin are chronically deactivated (e.g., Merzenich et al., Neuroscience 3:33-55, '83).     

Immunohistochemical detection of calcium/calmodulin-dependent protein kinase II in the spinal cord of the rat and monkey with special reference to the corticospinal tract

Calcium/ calmodulin-dependent protein kinase II is a prominent enzyme in the mammalian brain that phosphorylates a variety of substrate proteins. In the present study, monoclonal antibodies that specifically recognize either the α or the β isoforms of this enzyme were used to determine the distribution of these isoforms within the rat and monkey spinal cord. In the rat, the corticospinal tract consists of two components: the dorsal corticospinal tract, which occupies the ventralmost aspect of the dorsal funiculus; and the ventral corticospinal tract, which occupies an area adjacent to the ventral median fissure. Both dorsal and ventral corticospinal tract fibers were strongly immunopositive for the α-antibody. Unilateral ablation of the sensorimotor cortex of the rat eliminated the α-immunoreactive staining in the contralateral dorsal corticospinal tract. The neuropil in the superficial laminae of the dorsal horn (Rexed's laminae I and II) was densely stained with the α-antibody, whereas the neuropil in laminae IV-X was immunonegative. Dense α-immunopositive neurons were also distributed in the head of the dorsal horn (laminae I-IV). In contrast to the strong α-immunoreactivity seen in the dorsal corticospinal tract fibers, only very weak β-immunoreactivity was observed in this tract. Moderate β-immunoreactive products were distributed homogenously throughout the neuropil of the gray matter, although the neuropil of the superficial laminae of the dorsal horn (laminae I and II) was stained more strongly than the other regions of the gray matter (laminae III-X). Neuronal components in all laminae were immunopositive for the β-antibody. Thus, motoneurons in the ventral horn, which were immunonegative for the α-antibody, were immunopositive for the β-antibody. This selective distribution pattern of immunoreactivity of α- and β-antibodies in the rat was also present in the monkey spinal cord, although the α-immunopositive corticospinal tract fibers in the monkey descended in the lateral funiculus as the lateral corticospinal tract instead of passing through the dorsal funiculus, as is the case in the rat. The differential distribution of immunoreactivity in the spinal cord suggests that these two isoforms of calcium/ calmodulin-dependent protein kinase II may have different functional roles in the spinal cord. © Wiley-Liss, Inc.     

Central distribution of efferent and afferent components of the pudendal nerve in macaque monkeys

Central distribution of efferent and afferent components of the pudendal nerve was studied by the horseradish peroxidase (HRP) method in 13 macaque monkeys, i.e., in nine Japanese monkeys (Macaca fuscata), two rhesus monkeys (Macaca mulatta), and two crab-eating monkeys (Macaca fascicularis). The enzyme was applied to the central cut end of the pudendal nerve; then the monkeys were allowed to survive for 36 to 72 hr. Retrogradely labeled neuronal cell bodies of pudendal motoneurons constituted a slender longitudinal cell column in the ventral horn. The cell column extended from high or middle S1 to high or middle S2 in eight monkeys, from middle or low L7 to high S2 in four monkeys, and from high L7 to middle S1 in a monkey. The cell column appeared to correspond to Onuf's X nucleus in man. No sex difference was recognized in the position of the cell column. The average number of HRP-labeled pudendal motoneurons was larger in male than in female adult Japanese monkeys, whereas no sex difference was found in the average soma diameter of the pudendal motoneurons. Transganglionically labeled axons entered into the spinal cord through the S1 and S2 dorsal roots in 12 monkeys and through the L7 and S1 dorsal roots in one monkey. Labeled axons were distributed ipsilaterally in laminae I-VI and X of the spinal cord at the same and adjacent levels of entry of HRP-labeled dorsal root fibers (from L7 to S3 in 12 monkeys and from L6 to S3 in one monkey).(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential glutamatergic innervation in cytochrome oxidase-rich and -poor regions of the macaque striate cortex: Quantitative EM analysis of neurons and neuropil

One of the hallmarks of the primate striate cortex is the presence of cytochrome oxidase (CO)-rich puffs and CO-poor interpuffs in its supragranular layers. However, the neurochemical basis for their differences in metabolic activity and physiological properties is not well understood. The goals of the present study were to determine whether CO levels in postsynaptic neuronal compartments were correlated with the proportion of excitatory glutamate-immunoreactive (Glu-IR) synapses they received and if Glu-IR terminals and synapses in puffs differed from those in interpuffs. By combining CO histochemistry and postembedding Glu immunocytochemistry on the same ultrathin sections, the simultaneous distribution of the two markers in individual neuronal profiles was quantitatively analyzed. As a comparison, adjacent sections were identically processed for the double labeling of CO and GABA, an inhibitory neurotransmitter. In both puffs and interpuffs, most axon terminals forming asymmetric synapses (84%)—but not symmetric ones, which were GABA-IR—were intensely immunoreactive for Glu. GABA-IR neurons received mainly Glu-IR synapses on their cell bodies, and they had three times as many mitochondria darkly reactive for CO than Glu-rich neurons, which received only GABA-IR axosomatic synapses. In puffs, GABA-IR neurons received a significantly higher ratio of Glu-IR to GABA-IR axosomatic synapses and contained about twice as many darkly CO-reactive mitochondria than those in interpuffs. There were significantly more Glu-IR synapses and a higher ratio of Glu- to GABA-IR synapses in the neuropil of puffs than of interpuffs. Moreover, Glu-IR axon terminals in puffs contained approximately three times more darkly CO-reactive mitochondria than those in interpuffs, suggesting that the former may be synaptically more active. Thus, the present results are consistent with our hypothesis that the levels of oxidative metabolism in postsynaptic neurons and neuropil are positively correlated with the proportion of excitatory synapses they receive. Our findings also suggest that excitatory synaptic activity may be more prominent in puffs than in interpuffs, and that the neurochemical and synaptic differences may constitute one of the bases for physiological and functional diversities between the two regions. © 1996 Wiley-Liss, Inc.     

Differential effect of visual deprivation on cytochrome oxidase levels in major cell classes of the cat LGN

Cytochrome oxidase histochemistry was used to examine the effects of visual deprivation on the development of neurons in the lateral geniculate nucleus of the kitten. Early postnatal monocular suture results in a decrease in reactivity within the neuropil of visually deprived binocular laminae A, A1, magnocellular C, and medial interlaminar nucleus. Within these regions, monocular suture has a greater effect on the relative numbers of, and the growth of darkly reactive (normally large), presumed Y-cells than on other less reactive geniculate neuronal classes. The decreases in the reactivity of the neuropil may be attributed to the decreases in the number of mitochondria, the number of darkly reactive mitochondria, and/or the number of darkly reactive mitochondria localized within dendrites. Although all classes of dendrites appear to be adversely affected, the decrease in C.O. reactivity was most dramatic within the presumed proximal dendrites of class 1 Y-cells. These dendrites were identified by the type of synaptic contacts they formed with retinal terminals (Rapisardi and Miles, '84, J. Comp. Neurol. 223:515-534; Wilson et al., '84, Proc. R. Soc. Lond. [Biol.] 221:411-436). As with Y-cells, the effects of monocular suture on the large darkly reactive cells were not as dramatic at sites where binocular interactions were either absent or where they had been experimentally eliminated. Based on the present and previously reported findings from several laboratories, it is likely that the selective physiological and morphological effects of monocular suture on Y-cells are accompanied by metabolic deficits involving both dendrites and perikarya. These effects appear to be due more to binocular interactions than to visual deprivation per se.     

Morphological characteristics of acetylcholinesterase-containing neurons in the CNS of DFP-treated monkeys. Part 3. Brain stem and spinal cord.

The distribution of acetylcholinesterase (AChE, EC 3.1.1.7) was studied in the lower brain stem and spinal cord of 4 monkeys following the i.m. administration of bis-(1-methylethyl) phosphorofluoridate (di-isoprophylfluorophosphate: DFP). In 1 animal that received 0.43 mg/kg of DFP 4 hr prior to death, AChE was virtually absent in all structures. In the other 3 animals sacrificed 10, 12 and 18 hr after the injection of 0.20 mg/kg of DFP, AChE activity was considerably lighter in the neuropil of different structures normally displaying a moderate to intense AChE activity in pharmacologically unmanipulated monkeys. As a consequence of the lighter background activity several groups of neurons were easily identified and their cell bodies and processes were sharply outlined. Brain stem and spinal cord groups of neurons that show an intense AChE activity include the nuclei of the somatic motor column (cranial nerves III, IV, VI and XII, and ventral horn cells) and of the special visceral (cranial nerves V and VII and nucleus ambiguus) and general visceral (Edinger-Westphal and salivatory nuclei, dorsal nucleus of the Xth nerve and intermediomedial and intermediolateral spinal nuclei) motor columns. Other neurons of the midbrain that display intense AChE activity include the rostral division of nucleus linearis, the magnocellular division of the red nucleus, perirubral giant neurons, the nucleus of the mesencephalic root of V, the substantia nigra and the subnucleus compactus of the pedunculopontine tegmental nucleus. Midbrain neurons with a light to moderate AChE activity are located in the periaqueductal gray, the parvocellular division of the red nucleus, the interstitial nucleus of Cajal, and the magnocellular nucleus of the posterior commissure. Other intensely stained groups of neurons at isthmus and pontine levels include the intermediate and caudal divisions of nucleus linearis, all divisions of the dorsal nucleus of the raphé, the laterodorsal nucleus, nucleus annularis, nucleus centralis superior, neurons of the loci coeruleus and subcoeruleus and of the mesencephalic root of V, the few and large neurons of nuclei pontis oralis and pontis caudalis and nuclei paraabducens and paramedianus dorsalis. Other groups of neurons with a light to moderate AChE activity at isthmus and pons levels include the pontine and reticulotegmental nuclei. The neurons of the cerebellar fastigial nucleus are intensely stained and those of nucleus interpositus and nucleus dentatus, as well as the cell bodies of the Golgi cells of the cerebellar cortex, are moderately stained. At medulla and spinal cord levels the neurons of the lateral vestibular nucleus, the gigantocellular nucleus, the dorsal nucleus of Clarke and the lumbo-sacral border cells are intensely stained. Other neurons with lightly to moderately stained cell bodies include the superior and medial vestibular nuclei, nucleus praepositus, the lateral cuneate and lateral reticular nuclei, and the principal inferior and accessory olivary nuclei.     

Distribution of neurofilament proteins in the lateral geniculate nucleus, primary visual cortex, and area MT of adult Cebus monkeys

We investigated the distribution pattern of SMI-32-immunopositive cells in the lateral geniculate nucleus (LGN) and in the primary (V1) and middle temporal (MT) cortical visual areas of the adult New World monkey Cebus apella. In the LGN, the reaction for SMI-32 labeled cells in both the magnocellular (M) and parvocellular (P) layers. However, the cellular label was heavier in M layers, which also showed a more intense labeling in the neuropil. In V1, the reaction showed a lamination pattern, with the heaviest labeling occurring in layer 4B and upper layer 6 (layers that project to area MT). Area MT shows a dense band of labeled neuropil and large pyramidal neurons in layer 3, large darkly labeled but less densely packed neurons in layer 5, and a population of small, lightly labeled cells in layer 6. These results resemble those found in other New and Old World monkeys, which suggest that the preferential labeling of projection neurons associated with fast-conducting pathways to the extrastriate dorsal stream is a common characteristic of simian primates. In the superficial layers of V1 in Cebus monkeys, however, SMI-32-labeled neurons are found in both cytochrome oxidase blobs and interblob regions. In this aspect, our results in Cebus are similar to those found in the Old World monkey Macaca and different from those described for squirrel monkey, a smaller New World Monkey. In Cebus, as well as in Macaca, there is no correlation between SMI-32 distribution and the blob pattern.     

Organization of the zona incerta in the macaque: a Nissl and Golgi study.

The zona incerta has been implicated in the control of the initiation of saccadic eye movements in the primate. Complex interactions within the zona incerta must take place to integrate its varied inputs and to produce a coherent efferent signal in order for this function to occur. However, whether the anatomical substrates exist within the zona incerta to allow this integration to take place has not been established. The zona incerta in monkeys (Macaca mulatta) was examined in frontally, horizontally, and sagittally sectioned preparations stained for Nissl, myelinated fibers, or cytochrome oxidase, or impregnated by the Golgi technique. This nucleus can be separated into dorsal and ventral laminae on the basis of staining and morphological differences between these two subdivisions. Neurons are more densely packed, more darkly stained, and larger in the ventral lamina. In addition, the neuropil of the ventral lamina is much more intensely stained after cytochrome oxidase histochemistry. Two neuronal types, principal cells and interneurons, were identified on the basis of neuronal cell body, dendritic, and axonal features in Golgi-impregnated preparations. Principal cells have fusiform or polygonal somata (long axis from 18 to 40 microns) and dendrites that extend for up to 750 microns within the lamina in which the cell bodies are located. Putative local interneurons have small (12-16 microns), round or oval cell bodies with wavy dendrites (up to 400 microns). Numerous multilobed appendages and axon-like processes originate from these dendrites and make apparent contacts with other interneurons or with dendrites of principal cells. Dendrites of most neurons in both laminae are oriented preferentially along the principal axis, dorsolateral-to-ventromedial, of the nucleus. Therefore, within the limits of light microscopy, the zona incerta appears to possess the morphological heterogeneity to form complex intrinsic interactions. These interactions are hypothesized to form the integrative substrate for the large array of incertal inputs that are utilized to produce an efferent signal involved in the initiation of saccadic eye movements.     

Distribution of GABAergic neurons and terminals in the auditory system of the barn owl

Antisera to GAD (glutamic acid decarboxylase) and GABA were used to determine the distribution of GABAergic cells and terminals in the brainstem and midbrain auditory nuclei of the barn owl. The owl processes time and intensity components of the auditory signal in separate pathways, and each pathway has a distinctive pattern of GAD- and GABA-like immunoreactivity. In the time pathway, all the cells of the cochlear nucleus magnocellularis and nucleus laminaris receive perisomatic GABAergic terminals, and small numbers of GABAergic neurons surround both nuclei. The ventral nucleus of the lateral lemniscus (anterior division) contains both immunoreactive terminals and some GABAergic neurons. In the intensity pathway, dense immunoreactive terminals are distributed throughout the cochlear nucleus angularis, which also contains a small number of GABAergic neurons. The superior olive contains two GABAergic cell types and immunoreactive terminals distributed throughout the neuropil. All the neurons of the nucleus of the lateral lemniscus (ventral part) appear to be GABAergic, and this nucleus also contains a moderate number of immunoreactive terminals. Immunoreactive terminals are distributed throughout the neuropil of the ventral nucleus of the lateral lemniscus (posterior division), whereas multipolar and small fusiform GABAergic neurons predominate in the dorsal regions of the nucleus. The time and intensity pathways combine in the inferior colliculus. The central nucleus of the inferior colliculus contains a larger number of fusiform and stellate GABAergic neurons and a dense plexus of immunoreactive terminals, whereas the external nucleus contains slightly fewer immunoreactive cells and terminals. The superficial nucleus contains dense, fine immunoreactive terminals and a small number of GABAergic neurons.     

THE EFFECT OF NALOXONE AND MORPHINE ON 3H-1-LYSINE IN VIVO INCORPORATION INTO VARIOUS NEURONS SEPARATED FROM FIXED RAT BRAIN PREPARATIONS BY ULTRASONIFICATION: A COMPARISON OF MORPHINE EFFECTS BETWEEN WISTAR AND SPRAGUE-DAWLEY RATS

A procedure is described where by ultrasonification one can separate large neurons from their surrounding neuropil from either unfixed brain and peripheral ganglion or from similar tissue fixed in 10 per cent neutral formalin for prolonged periods. The availability of such a technique permits one to readily assess the accumulation of ³H-labeled protein precursors into a wide variety of neurons, utilizing standard liquid scintillation techniques. The separation technique has been applied in this report to determine the effects of morphine, morphine plus naloxone, naloxone given alone and saline on the accumulation of ³H-1-lysine into ventral horn, Purkinje and dorsal root ganglion neurons in Sprague-Dawley rats. The data from the control and morphine-treated animals has then been compared with similar data previously obtained from Wistar rats. In Sprague-Dawley rats, morphine had no effect on ³H-1-lysine accumulation into ventral horn neurons and stimulated accumulation into Purkinje and dorsal root ganglion neurons. Naloxone stimulated lysine accumulation into dorsal root ganglion and ventral horn neurons, but had equivocal effects on Purkinje neuron ³H-lysine accumulation. When Wistar and Sprague-Dawley rats were compared, marked differences in the effect which morphine had on lysine accumulation into neurons were noted between the two strains of rat. Ventral horn and dorsal root ganglion neurons from Wistar rats had markedly higher levels of accumulation in both control and morphine-treated rats than were observed in the Sprague-Dawley animals. With Purkinje neurons, accumulation levels between the two strains overlapped each other. Morphine inhibited lysine accumulation in Wistar Purkinje neurons but stimulated it in the Sprague-Dawley animals. The profiles of the accumulation curves from two rat strains suggest that there are not only differences in rates of uptake of ³H-lysine into protein followed by degradation between various types of neurons, but differences between the two strains as well.