Regional heterogeneity in the distribution of somatostatin-28- and somatostatin-28(1-12)-immunoreactive profiles in monkey neocortex

The distribution of the prosomatostatin-derived peptides (PSDP), somatostatin-28 and somatostatin-28(1-12), in the cynomolgus monkey (Macaca fascicularis) neocortex was characterized in quantitative immunohistochemical studies of 3 visual areas (V1, primary visual cortex; V2, the adjacent visual association area; and AIT, a visual association area in anterior inferior temporal cortex), 2 auditory areas (AI, primary auditory cortex; and T1, an adjacent auditory association area) and anterior cingulate cortex (Area 24). The results of similar quantitative analyses in 3 homologous areas in rat neocortex (primary visual, primary auditory, and anterior cingulate) are also presented. Primate cortical areas differed significantly in both density and laminar distribution of PSDP-immunoreactive profiles. Area 24, the most densely labeled area, had nearly 6 times as many PSDP-immunoreactive neurons as V1. Both auditory areas contained approximately two-thirds the number of PSDP-immunoreactive neurons found in Area 24; however, both had nearly 4 times as many immunoreactive neurons as V1. The 3 visual areas showed incremental increases in the number of PSDP-immunoreactive neurons; V2 contained nearly twice and AIT nearly 3 times the number of immunoreactive neurons present in V1. Both the supra- and infragranular layers were densely labeled in Area 24 and Area T1, however, in AI, V1, V2, and AIT the infragranular layers were relatively sparsely labeled. In contrast to the regional heterogeneity found in the primate neocortex, the distribution of immunoreactive neurons was quite uniform across the 3 rat cortical areas. The rat cortical areas contained substantially fewer immunoreactive neurons than most of the monkey cortical areas, and a majority of these immunoreactive neurons were located in the infragranular layers. These findings suggest that the regional specialization of primate neocortex involves the selective distribution of PSDP-immunoreactive neurons. They also suggest that chemically specified intrinsic organization of neocortex is not likely to be uniform across species or across cortical areas in the primate. The distinctive regional distribution patterns of PSDP-immunoreactive profiles appear to parallel that of the long corticocortical projections (contralateral and distant ipsilateral projections), suggesting an association between these presumed inhibitory interneurons and this important extrinsic system.     

Evidence for selective release of somatostatin-14 and somatostatin-28(1-12) from rat hypothalamus

Cysteamine administration to rats results in a marked depletion of hypothalamic somatostatin-14 (SS14) and a decrease of the potassium-evoked in vitro release of SS14 without a significant change in the content or release of somatostatin-28(1-12)-like immunoreactivity (SS28(1-12)-L1). Furthermore, cysteamine enhances the spontaneous release and markedly potentiates the potassium-evoked release of SS14 in the in vitro slice preparation. However, in vitro-administered cysteamine does not alter the spontaneous or potassium-evoked release of SS28(1-12)-LI. Immunohistochemical visualization of hypothalamic neuronal cell bodies and fibers following cysteamine administration shows a disappearance of the SS14 immunoreactive fibers and cell bodies with no apparent change in the SS28(1-12) immunoreactive fibers and cell bodies. These data suggest that, in rat hypothalamus, selective release of SS14 and SS28(1-12) can occur. The results are discussed in relation to possible sites of storage and release of the somatostatin-related peptides from synaptic nerve terminals.     

Somatostatin-28 (1-12)-like immunoreactivity in the cat diencephalon.

Using an indirect immunoperoxidase technique, the location of somatostatin-28 (1-12)-like immunoreactive fibres and cell bodies in the cat diencephalon was studied. The hypothalamus was richer in somatostatin-28 (1-12)-like immunoreactive structures than the thalamus. A high density of immunoreactive fibres was observed in the nuclei habenularis lateralis, paraventricularis anterior (its caudal part), filiformis, hypothalami ventromedialis, and regio praeoptica, whereas a moderate density was found in the nuclei paracentralis, supraopticus, supra chiasmaticus, hypothalamus posterior and area hypothalamica dorsalis. The nuclei lateralis dorsalis, lateralis posterior, medialis dorsalis, rhomboidens, centralis medialis, ventralis medialis, reuniens, anterior dorsalis, parataenialis, interanteromedialis, hypothalamus lateralis, hypothalamus dorsomedialis and arcuatus had the lowest density of immunoreactive fibres. In addition, a high or moderate density of somatostatin-28 (1-12)-like immunoreactive cell bodies was observed in the nuclei paraventricularis hypothalami, supraopticus, supra chiasmaticus, area hypothalamics dorsalis, subparafascicularis, hypothalamus posterior and hypothalamus anterior, whereas scarce immunoreactive perikarya were visualized in the nuclei lateralis dorsalis and parafascicularis. The distribution of somatostatin-28 (1-12)-like immunoreactive structures is compared with the location of other neuropeptides in the cat diencephalon.     

Distribution of luteinizing hormone-releasing hormone in the upper brainstem and diencephalon of the cat: an immunocytochemical study

The distribution of luteinizing hormone-releasing hormone (LH-RH)-immunostained cell bodies and fibres was studied in the brainstem and diencephalon of the cat using an indirect immunoperoxidase technique. The brainstem and the thalamus were devoid of immunostained cell bodies, whereas in the hypothalamus immunopositive perikarya were observed in the supraoptic nucleus, the anterior hypothalamus, the preoptic region and in the arcuate nucleus. Our findings also showed that the hypothalamus is richer in immunostained fibres, and that in this region such fibres are more widely distributed than in the thalamus and upper brainstem. No immunopositive fibres were observed in the lower brainstem. Our results point to a more widespread distribution of LH-RH-immunostained perikarya in the cat hypothalamus than that previously reported in the cat; a similar distribution to that found in the rat, and a more restricted distribution than in primates. Additionally, our study shows a more widespread distribution of immunostained fibres in the cat brainstem and diencephalon than that previously described for other mammals. In this context, our results describe for the first time in the mammals central nervous system fibres containing LH-RH located in the stria medullaris of the thalamus, the supramammillary decussation, the laterodorsal and lateroposterior thalamic nuclei, the nucleus reuniens, the supraoptic nucleus, and the optic chiasm. Thus, our findings reveal that LH-RH-immunostained structures are widely distributed in the upper brainstem and in the diencephalon of the cat, suggesting that the peptide may be involved in several physiological functions.     

Distribution of neurokinin A in the cat diencephalon: An immunocytochemical study

The distribution of neurokinin A-like immunoreactive cell bodies and fibers in the diencephalon of the cat was studied using an indirect immunoperoxidase technique. A high or moderate density of immunoreactive neurons was observed in the nuclei habenularis lateralis, median's dorsalis, parafascicularis, hypothalamus posterior, area hypothalamica dorsalis, hypothalamus lateralis, periventricularis hypothalami, above the corpus mamillare, and in the perifornical area, whereas scarce immunoreactive perikarya were visualized in the nuclei reuniens, hypothalami ventromedialis, hypothalamus dorsomedialis, and mamillaris lateralis. The highest density of fibers containing neurokinin A was found in the nuclei periventricularis anterior, rhomboidens, centralis medialis, periventricularis hypothalami, and supraopticus. In the regio praeoptica, area hypothalamica dorsalis, hypothalamus posterior, and in the perifornical area a moderate density of immunoreactive fibers was observed, whereas the nuclei habenularis lateralis, medialis dorsalis, mamillaris lateralis, parataenialis, reuniens, habenularis medialis, filiformis, hypothalamus dorsomedialis, hypothalami ventromedialis, arcuatus, and suprachiasmaticus showed a low density of neurokinin A immunoreactive fibers.     

Distribution of substance P-like immunoreactive structures in the brainstem of the adult human brain: an immunocytochemical study

The distribution of substance P-like immunoreactive (SPI) structures in the brainstem of the adult human was investigated by the avidin-biotinylated peroxidase complex method for immunocytochemistry. SPI structures were widely distributed in the brainstem, and particularly dense in the substantia nigra, peripheral portions of the colliculus inferior, central gray matter, parabrachial area, nucleus dorsalis tegmenti of Gudden, nucleus reticularis tegmenti pontis, nucleus tractus solitarii, nucleus dorsalis motorius nervi vagi, and nucleus tractus spinalis nervi trigemini.     

Atlas of serotonergic cell bodies in the cat brainstem: An immunocytochemical analysis

The localization and relative number of serotonergic (5HT) cell bodies in the brainstem of the cat were studied through the use of a specific immunocytochemical technique. A surprisingly large number of 5HT cells were found in regions in addition to the classical raphe nuclei (obscurus, pallidus, magnus, centralis superior, and dorsalis). Foremost among these were: the ventral medulla, just dorsal to the pyramidal tract and inferior olivary complex, and especially the area in and around the lateral reticular nucleus; the dorsal pons, surrounding the central reticular core, and in the central gray area; and a region in the mesencephalon, in and around the interpeduncular nucleus. The advantages and disadvantages of the existing schemas for subdividing and labeling groups of brain 5HT neurons are discussed.     

Somatostatin28(15-28), but not somatostatin28(1-12), affects central monoaminergic neurotransmission in rats.

The effects of intracerebroventricularly (icv) administered somatostatin28(SS28) fragments, SS28(1-12) and SS28(15-28), were investigated on central monoaminergic neurotransmission in rats. SS28(15-28) did not significantly influence the hypothalamic and striatal noradrenaline concentrations. In a dose-related manner, SS28(15-28) significantly increased the dopamine, dihydroxyphenyl acetic acid DOPAC), and serotonin concentrations in hypothalamus, but did not modify these measures in striatum. The other SS28 metabolite, SS28(1-12), had no statistically significant effects on the monoamine neurotransmission. SS28(15-28) (6 and 9 nmol) induced barrel rotation, while SS28(1-12) was ineffective following administration over a wide dose-range (3-18 nmol). In conclusion, SS28(15-28) influences the hypothalamic monoaminergic transmission and causes barrel rotation, whereas SS28(1-12) has no neurochemical or behavioural effects in these tests.     

Somatostatin(14) and -(28) but not somatostatin(1-12) hyperpolarize CA1 pyramidal neurons in vitro

The three major prosomatostatin-derived peptides found within CNS neurons are a 28-amino acid peptide (SS28), a cyclic 14 amino acid peptide (SS14) and a 12 amino acid peptide (SS1-12). Immunohistochemical studies demonstrate a differential distribution of these related forms of somatostatin within CNS neurons and have led to the suggestion that SS1-12 may represent the predominant neurotransmitter form of this family of peptides. Intracellular recordings from CA1 pyramidal neurons in the in vitro rat hippocampal slice revealed that application of SS14 and SS28 in nanomolar concentration produced neuronal hyperpolarization; synaptic responses, recorded extracellularly, were also reduced. In contrast, we were unable to demonstrate a pre- or postsynaptic action of SS1-12 on these neurons. These results do not support the hypothesis that SS1-12 functions as a central neurotransmitter in area CA1 of the hippocampus.     

Immunocytochemical localization of somatostatin-281–12 in the rat hypothalamus

Somatostatin-28 (SS28) is considered as a precursor of somatostatin-14 (SS14) and also of the remaining NH₂ terminus of SS28, the dodecapeptide SS28₁₋₁₂ which has been recently characterized. In order to study the cellular and subcellular localizations of SS28₁₋₁₂ in the rat hypothalamus, we have conducted a light and electron microscopic immunocytochemical study, using both the peroxidase-antiperoxidase and the immunogold technique. Several antisera which selectively recognize one or more of these 3 somtostatin-related peptides were used. In serial paraffin sections, it was observed that SS28₁₋₁₂ was contained in the same neuronal cell bodies which also contain SS28. These neurons were exclusively located in the previntricualr nucleus. All the antisera used also produced a strong staining in the external zone of the median eminence. At the electron microscopic level, the 3 peptides were exclusively localized in all the dense core vesicles in cell bodies and axons in the periventricular nucleus and terminals in the median eminence. These results strongly suggest that SS28₁₋₁₂ and SS14 originate from the precursor SS28 and that processing of the precursor occurs in the cell body. They also support the hypothesis that the 3 peptides are released simultaneously under appropriate stimulation.     

Visualization of endogenous glycine in cat retina: an immunocytochemical study with Fab fragments

Fab fragments of a glycine antiserum were prepared and used for immunocytochemical visualization of glycine in the cat retina. The use of Fab fragments in conjunction with Fab-specific secondary and tertiary antisera improved tissue penetration and made it possible to identify a number of the immunoreactive neurons. Staining was observed in several subpopulations of amacrine cells, including the A7(AII) rod amacrine. Multiple subpopulations of cone bipolar cells were also seen to be immunoreactive. Many neurons exhibited no detectable immunostaining, indicating that general metabolic levels of glycine do not interfere with the visualization of those cells that contain large amounts of endogenous glycine. The distribution of immunostaining appears to parallel the pattern of glycine labeling seen previously with autoradiographic techniques and implicates these cells in glycine-mediated neurotransmission.     

Serotoninergic neurons in the brainstem expressing FOS protein after orofacial noxious stimulation: an immunocytochemical double-labeling study

Employing an immunocytochemical double-labeling technique, we investigated the co-localization of FOS protein, the expression product of c-fos proto-oncogene induced by orofacial noxious stimulation, and serotonin in the rat brainstem. About 3.2%-25.6% of serotonin-like immunoreactive neurons and 6.2%-46.7% of FOS-like immunoreactive neurons in the raphe nuclei, reticular formation and ventrolateral subdivision of the midbrain periaqueductal gray exhibit FOS-like immunoreactivity and serotonin-like immunoreactivity, respectively. The present results provide further morphological evidence for the involvement of serotoninergic neurons in modulating the transmission of noxious information.     

Cholecalcin (28-kDa CaBP) in the rat cochlea. Development in normal and hypothyroid animals. An immunocytochemical study

The distribution of cholecalcin (28-kDa calcium-binding protein) in the cochlea of developing rats was followed by immunocytochemistry. In normal animals, the protein first appeared in utero in the cells of K?lliker's organ, a structure involved in the secretion of the tectorial membrane. The inner hair cells, followed by the outer hair cells, then became immunoreactive from the base of the cochlea to the apex. Their cuticular plate, the anchoring structure for stereocilia, was particularly labeled. The cells of K?lliker's organ lost their immunoreactivity after the first postnatal week, the time when they lose their secretory activity. During the same period, when the tunnel of Corti and the space of Nuel open, labeling appeared in the supporting cells. The neurons of the spiral ganglion were stained from the second postnatal week and the fibers of the cochlear nerve after the end of the first month. No difference was induced by thyroid deficiency until the second postnatal week. Thereafter, K?lliker's organ did not transform and its cholecalcin immunoreactivity persisted, together with the secretory activity. As a result, the tectorial membrane was greatly distorted and the mechanical properties of the organ of Corti were dramatically impaired. The supporting cells were labeled although the tunnel of Corti and the space of Nuel did not open. Staining of the spiral ganglion neurons was delayed. All the nervous structures of the cochlea were, however, stained at the end of the first postnatal month, as in normal animals, despite the irreversible complete deafness. Cholecalcin is thus present during development of the cochlea in both non-neuronal and neuronal structures, and is probably involved in very different processes in various types of cells.     

Hypothalamic somatostatin-14 and -28 biosynthesis: effects of anesthetics and hypophysectomy

Somatostatin-14 and -28 biosynthesis in rat hypothalami was assessed following intracerebroventricular injection of [³⁵S]cysteine, and subsequent reversed-phase HPLC separation of the labeled peptides. Identities of somatostatin-14 and -28 were verified using 3 HPLC buffer systems. The anesthetic employed during label administration itself influenced [³⁵S]cysteine incorporation into both somatostatins. Hypophysectomy diminished label incorporation into both peptides, suggesting that somatostatin has an inhibitory role in the control of growth hormone secretion.     

Effect of hypophysectomy on somatostatin-14 and somatostatin-28 biosynthesis in the rat hypothalamus

The in vivo incorporation of [³⁵S]cysteine into hypothalamic somatostatin-14 and somatostatin-28 was found to be substantially below normal in hypophysectomized rats. A smaller reduction in label incorporation into arginine vasopressin was also observed, while incorporation into acid-precipitable protein was normal. The diminution in somatostatin biosynthesis presumably reflects the absence of pituitary growth hormone secretion, while that in vasopressin synthesis may reflect the loss or disruption of vasopressin-producing cells.     

Age-related changes in hypocretin (orexin) immunoreactivity in the cat brainstem

Terminals of hypothalamic hypocretin-containing neurons are observed within brainstem nuclei involved in the control of sleep and wakefulness. Because aged humans, cats and other species exhibit changes in sleep and wakefulness in old age, we were interested in examining age-related changes in hypocretin/orexin projections to the following brainstem regions which are associated with the regulation of sleep and wakefulness: the dorsal raphe nucleus, the laterodorsal tegmental nucleus, the pedunculo-pontine tegmental nucleus and the locus coeruleus. Based upon the results of immunohistochemical determinations, in all the regions examined, round or oval ‘spot-like’ structures were observed in aged cats. Many of these ‘spot-like’ structures resembled enlarged varicosities of a nature that would be expected to disrupt hypocretin neurotransmission. In addition, a site-specific decrease in immunostaining was observed in the locus coeruleus in old cats compared with adult controls; this result likely reflects a decrease in the number of labeled fibers, which indicates that there occurs a degeneration of hypocretinergic function in conjunction with old age. The proceeding changes may account for some of sleep–wake disturbance which are observed in aged animals as well as elderly humans.     

Distribution of acetylcholine and catecholamine neurons in the cat brainstem: a choline acetyltransferase and tyrosine hydroxylase immunohistochemical study

The distribution of acetylcholine neurons in the brainstem of the cat was studied by choline acetyltransferase (ChAT) immunohistochemistry and compared to that of catecholamine neurons examined in the same or adjacent sections by tyrosine hydroxylase (TH) immunohistochemistry. The largest group of ChAT-positive (+) neurons was located in the lateral pontomesencephalic tegmentum within the pedunculopontine tegmental nucleus and the laterodorsal tegmental nucleus rostrally and within the parabrachial nuclei and locus coeruleus nucleus more caudally. TH+ neurons were found to be coextensive and intermingled with ChAT+ neurons in the dorsolateral pontomesencephalic tegmentum, where the number of ChAT+ cells (approximately 18,500) exceeded that of the TH+ cells (approximately 12,000). In the caudal pons, scattered ChAT+ neurons were situated in the ventrolateral tegmentum together with TH+ neurons. In the medulla, numerous ChAT+ cells were located in the lateral tegmental field, where they extended in a radial column from the dorsal motor nucleus of the vagus to the ventrolateral tegmentum around the facial and ambiguus nuclei, occupying the position of preganglionic parasympathetic neurons of the 7th, 9th, and 10th cranial nerves. TH+ cells were also present in this field. Neurons within the general visceral, special visceral, and somatic motor cranial nerve nuclei were all immunoreactive to ChAT. Scattered ChAT+ neurons were also present within the medullary gigantocellular and magnocellular tegmental fields together with a small number of TH+ neurons. Other groups of ChAT+ cells were identified within the periolivary nuclei, parabigeminal nucleus, prepositus hypoglossi nucleus, and the medial and inferior vestibular nuclei. Acetylcholine neurons thus constitute a heterogeneous population of cells in the brainstem, which in addition to including the somatic and visceral efferent systems, comprises many other discrete systems and represents an important component of the brainstem reticular formation. The proximity to and interdigitation with catecholamine neurons within these systems may be of important functional significance.     

Immunocytochemical localization of somatostatin-28 in the rat hypothalamus

Somatostatin-28 (SS28) is considered as a precursor of somatostatin-14 (SS14) and also of the remaining NH₂ terminus of SS28, the dodecapeptide SS28₁₋₁₂ which has been recently characterized. In order to study the cellular and subcellular localizations of SS28₁₋₁₂ in the rat hypothalamus, we have conducted a light and electron microscopic immunocytochemical study, using both the peroxidase-antiperoxidase and the immunogold technique. Several antisera which selectively recognize one or more of these 3 somtostatin-related peptides were used. In serial paraffin sections, it was observed that SS28₁₋₁₂ was contained in the same neuronal cell bodies which also contain SS28. These neurons were exclusively located in the previntricualr nucleus. All the antisera used also produced a strong staining in the external zone of the median eminence. At the electron microscopic level, the 3 peptides were exclusively localized in all the dense core vesicles in cell bodies and axons in the periventricular nucleus and terminals in the median eminence. These results strongly suggest that SS28₁₋₁₂ and SS14 originate from the precursor SS28 and that processing of the precursor occurs in the cell body. They also support the hypothesis that the 3 peptides are released simultaneously under appropriate stimulation.     

Distribution of corticotropin-releasing-factor-like immunoreactivity in brainstem of two monkey species (Saimiri sciureus and Macaca fascicularis): an immunohistochemical study

Immunohistochemical methods were utilized to systematically map the distribution of corticotropin-releasing-factor-like immunoreactivity (CRF-LI) in the diencephalon, mesencephalon, and rhombencephalon of two monkey species (Saimiri sciureus and Macaca fascicularis). A primary antiserum directed against the human form of the peptide was utilized. Immunoreactive neuronal perikarya and processes were evident in numerous areas, and the distributions of these elements were similar for the two species. As previously reported for rats, monkeys, and human, intense immunoreactivity was evident in putative hypophyseal neurons in the parvicellular component of the paraventricular nucleus of the hypothalamus and in fibers extending from this area into the median eminence. The results for other brainstem regions, most of which have been previously examined for CRF-LI only in rats, indicate that many similarities exist between rats and monkeys in the distribution of this peptide in brainstem extrahypophyseal neuronal circuits, although substantial differences are also evident. For example, immunoreactive perikarya previously observed in other hypothalamic nuclei in rats were not evident in monkeys. Conversely, in monkeys, unlike rats, labeled perikarya were evident in several thalamic nuclei, especially in the intralaminar complex. Also, two large groups of immunoreactive neurons which have generally not been observed in rat studies were present in the mesencephalon and rhombencephalon. In the mesencephalon this consisted of a group of neurons just lateral to the mesencephalic tegmentum, extending throughout the rostral-caudal extent of the midbrain. In the rhombencephalon, labeled perikarya were observed throughout the inferior olive. Some of the differences between rats and monkeys in the locations of labeled perikarya may be due to differences in antiserum specificity and/or sensitivity, or they may result from the fact that colchicine pretreatment was not utilized in the present study. The distributions of immunoreactive fibers also exhibited similarities and differences between monkeys and rats. The most striking terminal fields observed in the present study which have not been previously described are a moderate-to-dense field within and adjacent to presumed dopamine-containing neurons in the substantia nigra pars compacta, a dense innervation of certain subdivisions of the interpeduncular nucleus, and a regionally and parasagittally organized distribution of fibers in the Purkinje cell and molecular layers of the cerebellar cortex.(ABSTRACT TRUNCATED AT 400 WORDS)     

Distribution of histamine in the cockroach brain and visual system: an immunocytochemical and biochemical study

The distribution of histamine-immunoreactivity in the carbodiimide-fixed brain and visual system of the cockroach was revealed immunocytochemically with an antiserum against histamine (HA). Histamine levels were measured with high-pressure liquid chromatography. The results show a widespread distribution of histamine-containing somata and fibers in the brain, particularly in the visual system. The most intense immunolabeling was seen in the retinal photoreceptors and in the first optic ganglion, the lamina, where the short visual fibers make synaptic connections with the monopolar neurons, which also displayed immunofluorescence. Immunoreactive long visual fibers traversed the lamina and outer chiasma, terminating in the distal medulla. Tracts of histamine-immunopositive fibers appeared to link the optic ganglia to the protocerebrum. Prominent histamine-containing neurons were situated in the lateral protocerebrum. Immunolabeled pathways consisting of large-diameter fibers also were seen in the cockroach brain. The central parts of the brain, including the central body, were reached by thick immunoreactive fibers that gave rise to intensely fluorescent varicose processes there. In the mushroom bodies, immunoreactivity was limited to the calyces. The protocerebral bridge was nonreactive. Immunofluorescence was seen also in the antennal lobes, but not in the antennal nerves. The biochemical measurements correlated well with the immunocytochemical data. The retinas and optic lobes, measured together, contained remarkably large amounts of histamine. These results reinforce the hypothesis presented by Hardie ('87) and Elias and Evans ('83) that histamine functions as a neurotransmitter in the photoreceptors of some, if not all, insect species.