Differential localization of four subspecies of protein kinase C in the rat striatum and substantia nigra.

The distribution of protein kinase C (PKC) subspecies and their colocalization with neurotransmitters were examined in the rat striatum and substantia nigra (SN), using immunocytochemistry. The alpha- and beta I-PKC immunoreactivies were seen predominantly in the perikarya of the neurons in the striatum and SN. In contrast, the beta II- and gamma-PKC immunoreactivities were abundant in both the perikarya and the neuropils in the striatum and only in the neuropils in the SN. From electron microscopic studies, the alpha- and beta I-PKC immunoreactivities were seen adjacent to the plasma membrane, while the beta II-PKC immunoreactivity was observed in the cytoplasm around the Golgi complex. The gamma-PKC immunoreaction was dense throughout the cytoplasm. The double-staining and lesion studies revealed that the alpha-PKC-immunopositive neurons in the striatum were intrinsic cholinergic neurons, and that most of the alpha-PKC-immunoreactive neurons in the SN were dopaminergic neurons. The beta I-PKC-immunoreactive neurons were intrinsic GABAergic neurons in the striatum. Moreover, most of the beta II- and gamma-PKC-immunoreactive neurons were medium-sized neurons projecting to the SN, and over 90% of GABAergic neurons in the caudate-putamen contained beta II-PKC. The beta II-PKC-immunoreactive neurons showed no gamma-PKC immunoreactivity, and the gamma-PKC-immunoreactive neurons were not beta II-PKC immunoreactive. These findings suggest that alpha-PKC is related to the function of the nigral dopaminergic and the striatal cholinergic neurons, and that the beta I-PKC is involved in the function of the striatal intrinsic GABAergic neurons. The beta II- and gamma-PKC may also modulate a specific neuronal function in the striatonigral system.     

The loss of beta II-protein kinase C in the striatum from patients with Huntington's disease.

We have examined the levels of protein kinase C (PKC) in autopsied brains of patients with Huntington's disease (HD), using [3H]4-beta-phorbol-12,13-dibutyrate ([3H] PDBu) and antisera against the PKC subspecies. In the caudate nucleus and putamen from patients with HD, the specific binding for [3H]PDBu was significantly decreased by 74 and 68%, respectively, as compared to findings in controls. The beta II-PKC immunoreactivities were significantly reduced by 65%, whereas the alpha-PKC immunoreactivities increased by 146%, in the putamen. There were no differences in the beta I- or gamma-PKC immunoreactivities in the putamen between HD and controls. These results suggest the differential localization of four PKC subspecies in human striatum and the involvement of four subspecies in different aspects of HD pathophysiology.     

Light and electron microscopic localization of beta I-, beta II-, and gamma-subspecies of protein kinase C in rat cerebral neocortex.

We have localized the beta I-, beta II-, and gamma-subspecies of protein kinase C in cerebral neocortex with light and electron microscopic immunocytochemistry using a monoclonal antibody against gamma-PKC and polyclonal antisera to beta I- or beta II-PKC-specific oligopeptides. The gamma-PKC-immunopositive cell bodies were seen mostly in layers II, V, and VI, and the vast majority of them were pyramidal cells. The beta II-PKC immunoreactive cell bodies were observed in layers II, III, V, and VI, and most of them seemed to be pyramidal cells. Both gamma- and beta II-PKC were colocalized in some pyramidal cells in layers II, V, and VI. The small number of beta I-PKC immunoreactive cell bodies were observed in the neocortex, and many of them were nonpyramidal cells. About 80% of the beta I-PKC-immunoreactive cells were shown to be GABAergic neurons. The gamma-PKC-immunopositive neuropils were observed in layers I, II, V, and VI, while beta II-PKC-immunoreactive neuropils were seen in layers I-III, V, and VI. The distribution of each subspecies is much the same throughout all regions of the neocortex, although with different intensities of immunoreactivity. electron microscopic studies revealed that, in the perikarya, gamma-PKC was distributed throughout the cytoplasm, beta I-PKC was just adjacent to the plasma membrane, and beta II-PKC was located around the Golgi complex. The immunoreactivity of these 3 subspecies was also seen in dendrites and axons, but no immunoreactivity of these subspecies was found in the presynaptic terminals in the present study. The discrete cellular and intracellular distributions of protein kinase C subspecies imply that each subspecies has a specific role in neuronal activity in the cerebral neocortex.     

Developmental changes in the levels of Ca2+/calmodulin-dependent protein kinase II alpha and beta proteins in soluble and particulate fractions of the rat brain.

Developmental changes in Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) have been immunochemically examined in the forebrain, cerebellum and brainstem of the rat using antibodies against its alpha or beta protein. The concentration of alpha and beta proteins varied markedly in different brain regions at increasing postnatal ages. In early postnatal brain, the concentration of the alpha and beta proteins was low, and a large increase was observed between postnatal days 10 and 30. The maximum expression of the alpha protein was in the order of 6.01, 2.33 and 0.168 micrograms/mg of forebrain, brainstem and cerebellum proteins respectively, in the soluble or particulate fraction. On the other hand, that of the beta protein was in the order of 1.81, 0.495 and 0.291 micrograms/mg of forebrain, cerebellum or brainstem protein. The ratio of alpha and beta proteins also differed in the soluble and particulate fractions. The maximum expression of the alpha protein was observed at day 30 in soluble and particulate fractions of forebrain, and at day 20 in those of the brainstem. The major alpha protein peak was observed on or after day 30 in particulate and soluble fractions from cerebellum, respectively. The maximum expression of the beta protein was observed at day 20 in soluble and particulate fractions of the forebrain as well as in soluble fraction of the cerebellum, and was observed at day 30 in the particulate fraction of cerebellum. The expression of the alpha and beta proteins roughly correlated with the CaM kinase II activity from forebrain and brainstem.     

Different postnatal ontogenic profiles of neurons containing beta (beta 1, beta 2 and beta 3) subunit mRNAs of GABAA receptor in the rat thalamus.

The postnatal ontogeny of neurons containing different GABAA receptor beta (beta 1, beta 2 and beta 3) subunit mRNAs were examined in the rat thalamus using in situ hybridization histochemistry. Neurons containing beta 1 or beta 2 subunit mRNA developed remarkably postnatally, while most neurons were already strongly labeled with beta 3 probe at birth. However, beta 3 subunit mRNA decreased rapidly after birth, few cells being labeled with this probe at day 35 and thereafter.     

The loss of βII-protein kinase C in the striatum from patients with Huntington's disease

We have examined the levels of protein kinase C (PKC) in autopsied brains of patients with Huntington's disease (HD), using [³H]4-β-phorbol-12,13-dibutyrate ([³H] PDBu) and antisera against the PKC subspecies. In the caudate nucleus and putamen from patients with HD, the specific binding for [³H]PDBu was significantly decreased by 74 and 68%, respectively, as compared to findings in controls. The βII-PKC immunoreactivities were significantly reduced by 65%, whereas the α-PKC immunoreactivities increased by 146%, in the putamen. There were no differences in the βI- or γ-PKC immunoreactivities in the putamen between HD and controls. These results suggest the differential localization of four PKC subspecies in human striatum and the involvement of four subspecies in different aspects of HD pathophysiology.     

Immunocytochemical localization of a neuron-specific diacylglycerol kinase beta and gamma in the developing rat brain

Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to produce phosphatidic acid (PA) and is, therefore, a potential terminator of DG signaling. DG and PA are important intracellular second messengers. DG directly binds protein kinase C (PKC) then activates this multifunctional enzyme. Ca2+-dependent and brain-specific DGKs, alpha, beta, and gamma, are suggested to play pivotal roles in the central nervous system. To elucidate the DGK function in neuronal development, we studied the developmental changes of DGKalpha, beta, and gamma in the postnatal rat brain. By immunoblot analysis, DGKalpha and gamma subtypes were present at birth and then gradually increased, while DGKbeta was not present at birth or postnatal day 3, then increased rapidly from day 14 to reach maximum at day 28. Immunohistochemically, DGKbeta and gamma were distributed in different brain regions. In most brain regions, DGKgamma showed sustained expression throughout the postnatal developmental periods. Interestingly, a temporal expression of DGKgamma was observed in the medial geniculate nucleus during day 3 to 14, and a delay of DGKgamma expression was seen in Purkinje cells, which was coincident with dendritic growth of Purkinje cells. In the hippocampal pyramidal cell, both DGKbeta and gamma were abundant but subcellular localization was different. DGKgamma localized in the cytosol while DGKbeta localized along the membrane structure. These findings suggest that each DGK subtype has a spatio-temporally different function in the developmental neurons.     

Appearance of neuronal S-100β during development of the rat brain

In addition to being an astroglial protein, S-100β is localised in distinct populations of neurons in the adult rat hindbrain. We report, here, the expression of S-100β in both neurons and glia of the rat brain during development. Prenatally, S-100β immunoreactivity was confined to glial cells close to the germinal zone. After birth, S-100β positive glial cells were seen mainly in the brainstem and cerebellum, while only a few were detected in cerebral cortex and hippocampus. The number of S-100β containing glial cells increased steadily during the first 2 postnatal weeks after which the adult pattern was attained. No S-100β containing neurons were present prenatally. The first S-100β containing neurons were seen in the mesencephalic trigeminal nucleus at postnatal day 1 (P1), and in the motor trigeminal nucleus at P3. Neuronal S-100β immunoreactivity in other nuclei was mostly attained from the 10th to the 21st postnatal day. The neuronal S-100β immunoreactivity was first detected in the cell nuclei during development, then increased in the cytoplasm with ages. A nuclear staining in many immunoreactive neurons persisted until the adult. It usually took 1 to 2 weeks for neuronal S-100β to attain the adult staining pattern, i.e., heavy staining of the cytoplasm and processes, after its appearance. The forebrain never contained S-100β positive neurons. The S-100β is first expressed in glial cells, suggesting it is primarily of the glial origin. Coupled with neurotrophic effects of the protein, the time course of neuronal S-100β expression during the critical period of neuronal development implies that it may be involved in neuronal differentiation and maturation.     

Different postnatal development profiles of neurons containing distinct GABAA receptor beta subunit mRNAs (beta 1, beta 2, and beta 3) in the rat forebrain.

The expression of three beta subunit (beta 1, beta 2, and beta 3) mRNAs for gamma-aminobutyric acidA receptor in the postnatal rat forebrain was examined by in situ hybridization histochemistry with probes synthesized for the respective subunit mRNAs. The developmental expression of these subunit mRNAs conformed to one of three patterns. Pattern I was high expression of the mRNA at birth and a constant or increasing expression thereafter. In contrast, pattern II was no or very low expression of the mRNA at birth, with expression quickly increasing to reach the adult level in the early postnatal period. Pattern III was the transient expression of the subunit mRNA or else a marked decrease of its expression after a peak in the early postnatal period. On the basis of this classification, the expression of beta 3 subunit mRNA followed pattern I in most regions of the forebrain, such as the isocortex, the olfactory bulb and some of its related areas, the hippocampal formation, the amygdala, the septum, the bed nucleus of the stria terminalis, the caudate-putamen, the nucleus accumbens, the globus pallidus, the ventral pallidum, and the hypothalamus. In some areas, such as the magnocellular preoptic nucleus, the thalamus, and the subthalamic nucleus, pattern III was seen for this subunit. However, none of the regions of the brain showed pattern II expression of beta 3 subunit mRNA. In contrast, the expression of beta 1 and beta 2 subunit mRNAs followed pattern II in most regions of the forebrain. These included the expression of beta 1 subunit mRNA in the isocortex, the olfactory bulb, the hippocampal formation, the amygdala, the septum, the bed nucleus of the stria terminalis, the thalamus, and the hypothalamus, and the expression of beta 2 subunit mRNA in the isocortex, the olfactory bulb and some of its related areas, the amygdala, the nucleus of the diagonal band, the caudate-putamen, the thalamus, and the hypothalamus. Pattern I was not found for beta 1 subunit mRNA, although it was seen in some areas for beta 2 subunit mRNA, such as the ventral pallidum, the globus pallidus, and the magnocellular preoptic nucleus. On the other hand, pattern III was followed by beta 1 subunit mRNA in the anterior olfactory nucleus, the olfactory tubercle, and the piriform cortex, and the same pattern for the beta 2 subunit was also found in the olfactory tubercle, the hippocampal formation, the septum, the bed nucleus of the stria terminalis, and the nucleus accumbens.(ABSTRACT TRUNCATED AT 400 WORDS)     

Immunocytochemical localization of protein kinase C subspecies in the rat spinal cord: light and electron microscopic study

Distinct expression of protein kinase C (PKC) subspecies in the central nervous system suggested that each subspecies has a distinct neural function in the processing and modulation of a variety of physiological responses to external signals. In this study, the cellular and subcellular distributions of beta I-, beta II- and gamma-subspecies of PKC were demonstrated by using subspecies-specific antibodies in the rat spinal cord. By light microscopy both gamma- and beta II-subspecies immunoreactivities were found only in neurons of the substantia gelatinosa and axons of the dorsal corticospinal tract in the spinal cord. Use of a double staining method, however, revealed that beta II-subspecies immunoreactivity was localized in the outer part of the lamina II, whereas gamma-subspecies immunoreactivity was found in the inner part of lamina II. Immunoreactive neurons containing beta I-subspecies were scattered in the substantia gelatinosa. Beta I-subspecies immunoreactivity varied in neuronal types. Furthermore, electron microscopic analysis clearly showed the subcellular distribution of these subspecies to be different from one another. Dense gamma-subspecies immunoreactivity was found in the cytoplasm except within cell organelles of the perikarya and dendrites. Some nuclei were stained as strongly as the cytoplasm and others were stained less heavily. The nucleoli had faint or no immunoreactivity. Reaction products of beta II-subspecies were located against the inner plasma membrane but not seen in the nuclei or nucleoli. Beta I-subspecies immunoreactivity appeared to be associated with the Golgi complex. No immunoreactive products of any PKC subspecies were detected in the presynaptic terminals. The different patterns of expression described above imply that individual PKC subspecies may have a specific function in modulating the neuronal activity in the different neurons of the spinal cord.     

S-100 beta and insulin-like growth factor-II differentially regulate growth of developing serotonin and dopamine neurons in vitro.

To study the phenotypic specificity of S-100 beta and insulin-like growth factor II (IGF-II) for developing monoamine neurons, serotonin (5-HT) neurons from the embryonic day 14 (E14) rostral raphe or dopamine (TH) neurons from the substantia nigra/ventral tegmental area were cultured for 3 days in vitro (3 DIV) in the presence of these factors. Neuronotrophic effects were analyzed by computer-assisted morphometry of 5-HT and TH-immunoreactive neurons. S-100 beta and IGF-II differentially regulated the growth of 5-HT and TH neurons but did not affect their survival. S-100 beta significantly increased several parameters of neurite outgrowth by 5-HT neurons but inhibited the spatial extent (field area) of TH neurites. IGF-II promoted growth of cell bodies of both phenotype, but only stimulated neurite outgrowth by TH neurons. S-100 beta and IGF-II differentially affected the number of GFAP immunoreactive cells from raphe and substantia nigra, but these effects did not correlate with the specificity of neuronotrophic effects. S-100 beta and IGF-II immunoreactivities were expressed in glial cultures derived from the same brain regions, raising the possibility that these factors have autocrine effects on glia as well as paracrine actions on neurons. The results of this study suggest that specificity of neurotrophic factors for particular embryonic neurons may be correlated with their neurotransmitter phenotype.     

Development of histamine-immunoreactive neurons in the rat brain

This study was undertaken to reveal the cellular stores of histamine in developing rat brain and to determine the stage of development during which the histamine-immunoreactive neurons can first be detected. Rats from embryonal day 12 to postnatal day 14 were studied. The brains were fixed in 4% 1-ethyl-3(3-dimethylaminopropyl)carbodiimide and standard immunofluorescence technique was used. The first histamine-immunoreactive neurons were seen on embryonic day 13 in the border of mesencephalon and metencephalon. On embryonic day 15 immunoreactive neurons were detected in ventral mesencephalon and rhombencephalon. In caudal, tuberal, and postmammillary caudal magnocellular nuclei histamine-immunoreactive neurons were first detected on embryonic day 20 while those in the hindbrain had disappeared. Histamine-immunoreactive nerve fibers were first detected on embryonic day 15 in rhombencephalon and mesencephalon and in some areas of diencephalon including the mammillary bodies and frontal cortex. On embryonic day 18 the number of immunoreactive nerve fibers in the hindbrain had decreased considerably, but the olfactory bulb, septal and hypothalamic area, and the cerebral cortex showed immunoreaction in fibers. The density of histamine-immunoreactive fiber networks increased until postnatal day 14 when an adultlike pattern of neurons and fibers had developed. Histamine-immunoreactive neurons are present in embryonal CNS and they develop extensive projections to various brain areas.     

Autoradiographic study of beta 1-adrenergic receptor development in the mouse forebrain

The development of beta 1-adrenergic receptors has been studied in the mouse forebrain from embryonic day 14 (E14) to adulthood, using autoradiographic visualization of [125I]iodocyanopindolol (ICYP) binding sites. From E14, ICYP binding sites are detected in moderate amounts in the striatum and basal forebrain and in very low concentration in the cortical plate. At E17, binding sites have increased in number in the deep layers of the embryonic cortex and extend over the whole thickness of the cortical ribbon at birth. On postnatal day 4 (P4), ICYP binding sites are more abundant in the superficial than in the inner cortex. By P10 the adult pattern of ICYP binding site distribution is achieved, namely: a high concentration in ventral pallidum, striatum and cortical layers I, II and III, a moderate concentration in layers V and VI and a lower density in septal areas and in cortical layer IV. It is well established that norepinephrine fibers arrive in the embryonic cortex early in development. The present results show that the development of norepinephrine fiber and beta 1 receptor systems are coincident in the mouse.     

The blood-brain barrier for catecholamines — Revisited

Although it is well-recognized that catecholamines are generally unable to penetrate the developed blood-brain barrier (BBB) to gain entry into brain, except at circumventricular sites where the BBB is absent or deficient, ontogenetic development of this barrier seems to have escaped systematic study. To explore BBB development, several approaches were used. In the first study rats were treated once on a specific day of postnatal ontogeny, as early as the day of birth, with the neurotoxin 6-hydroxydopamine (6-OHDA; 60 mg/kg), and then terminated in adulthood for regional analysis of endogenous norepinephrine (NE) content of brain. In another study, rats were treated once, on a specific day of postnatal ontogeny, with the BBB-permeable neurotoxin 6-hydroxydopa (6-OHDOPA; 60 mg/kg) following pretreatment with the BBB-impermeable amino acid decarboxylase inhibitor carbidopa (100 mg/kg IP), then terminated in adulthood for regional analysis of endogenous NE content of brain. In the third study rats were treated once, on a specific day of postnatal ontogeny, with the analog [3H]metaraminol, and terminated 1 hour later for determination of regional distribution of tritium in brain. On the basis of [3H]metaraminol distribution and NE depletions after neurotoxin treatments, it is evident that the BBB in neocortex, striatum, cerebellum and other brain regions forms in stages over a period of at least 2 weeks from birth. Moreover, because the BBB consists of several element (physical-, ion-restrictive-, and enzymatic-barrier), the method employed will derive data mainly applicable to the targeted aspect of the barrier, which may or may not necessarily coincide with elements of the barrier that have a different rate of ontogenetic development. Accordingly, it is evident that some aspects of physical- and ion-restrictive elements of the BBB form within approximately the first week after birth in rat neocortex and striatum, while enzymatic elements of the BBB form more than than 2 weeks later. Regardless, the BBB forms at earlier times in forebrain vs hindbrain regions.     

Postnatal development of a brain-specific subspecies of protein kinase C in rat

Protein kinase C in the developing rat brain was investigated by a biochemical assay and by light-microscopic immunocytochemistry. The protein kinase was resolved on hydroxyapatite column chromatography into 3 fractions, designated types I, II, and III. Type I, with structure encoded by a gamma-sequence, was not detected early postnatally, maintained a low level of activity during the first week, which increased gradually, and reached its maximum around postnatal day 28. This type of enzyme was expressed specifically in nervous tissues, and was not found in any other tissues thus far tested. Type II enzyme activity, a mixture of the 2 subspecies encoded by the beta I- and beta II-sequences, was found at birth, increased rapidly, and reached a plateau level between postnatal days 14 and 28. This type was the predominant subspecies of protein kinase C in the brain. Type III, its structure encoded by the alpha-sequence, was also detected at birth, and reached its maximum level on postnatal day 7. Immunocytochemical studies with a monoclonal antibody, which recognized preferentially the type I enzyme, visualized the developmental pattern of type I subspecies in the Purkinje cell, a typical cell having a large quantity of type I protein kinase C.     

Electron microscopic localization of gamma- and beta II-subspecies of protein kinase C in rat hippocampus

The subcellular distributions of the gamma- and beta II-subspecies of protein kinase C (gamma- and beta II-PKC) were studied in the rat hippocampus by light and electron microscopic immunocytochemistry. Both subspecies were abundant in the hippocampus with distinct subcellular distributions. The immunoreactivity of gamma-PKC was observed throughout the Ammon's horn, while intense beta II-PKC immunoreactivity was observed predominantly in the CA1 region. gamma-PKC was distributed diffusely through the cytoplasm of pyramidal cells from the perikarya to the dendritic spines. In contrast, beta II-PKC was concentrated around the Golgi complex and present diffusely in distal dendrites, except for the dendritic spines. Neither PKC subspecies could be detected in the presynaptic terminal. The postsynaptic localization of gamma- and beta II-PKC in CA1 suggests that both PKC subspecies may correlate to long-term potentiation in the CA1 region contributing to the postsynaptic side. gamma-PKC may have a specific function not only in CA1 but also in the mossy fiber-CA3 pathway at the postsynaptic side. beta II-PKC may have another function concerning the Golgi complex in CA1.     

Ontogeny of somatostatin mRNA-containing perikarya in the rat central nervous system.

The distribution of neuronal perikarya containing somatostatin mRNA in the developing rat brain was investigated with in situ hybridization histochemistry. This study describes the expression of somatostatin mRNA during selected perinatal stages and demonstrates regional changes in somatostatin mRNA expression at the single cell level. The mRNA expression closely parallels previously reported developmental localization of the peptide (Inagaki et al., 1982; Shiosaka et al., 1982). As early as embryonic day 13 (E13), somatostatin mRNA was observed in discrete spinal cord and brainstem regions. At birth, densely hybridized somata could be seen primarily in ventral and caudal brain areas with small scattered neurons in the hippocampus and dorsal neocortex. After birth, somatostatin mRNA increased in forebrain regions, such as the hippocampus, dorsal neocortex, and caudate. By postnatal day 14 (P14), the distribution in the telencephalic and diencephalic regions approached that of the adult brain. Several brain regions manifested large changes in the density of somatostatin mRNA hybridization during development. For example, the cerebellar vermis and brainstem contained somatostatin mRNA perikarya during early postnatal development but decreased in these regions in the adult. During perinatal development, increases in somatostatin mRNA content were the results of increases in both the number of neurons containing somatostatin mRNA as well as in the amount of this mRNA expressed in each cell. As the brain differentiates, the apparent numbers of somatostatin mRNA containing neurons in certain brain regions are reduced. These data provide evidence for transient somatostatinergic neurons during early development in discrete areas of the occipital cortex, pyriform cortex, cerebellum, and brainstem and suggest that this peptide may play a role in the development of these regions.     

Effects of prenatal exposure to amphetamine in the medial prefrontal cortex of the rat

This study was designed to investigate the effects of prenatal exposure to amphetamine in the organization of the medial prefrontal cortex of the rat, by an evaluation of growth, morphometric and neurochemical parameters. Pregnant Wistar rats were given 10 mg/kg body weight/day of D-amphetamine sulfate, subcutaneously, from gestational days 8 to 22. Control groups of pregnant rats were injected with saline, pair-fed or non-manipulated; litters were culled to eight pups (four males and four females), weighed every other day until postnatal day 30 and every week until day 90. The Gompertz model was used to study body weight evolution and the estimated growth parameters were not significantly different in the experimental groups. At postnatal days 14 and 30, the volumes of the prefrontal cortex, the fraction of neuropile occupied by neurons and the number of neurons per unit surface area were determined. The number of neurons per unit volume of reference area was calculated using the stereological technique of the dissector. For neurochemical analysis, the medial prefrontal cortex was dissected to measure the concentration of dopamine, serotonin and their metabolites. The allometric relationship of forebrain/body growth pointed to a mechanism of sparing and compensatory growth in the amphetamine exposed group. The changes found in the number of neurons per unit volume at postnatal day 14 show a catch-up at postnatal day 30. A decrease in serotonin levels was found in the amphetamine group compared with the pair-fed control, which was reflected in the ratio of serotonin to its metabolite, 5-hydroxyindolacetic acid. These changes, whether permanent or transitory, raise the possibility that some of the effects of prenatal exposure to amphetamine may be due to modifications in the neurotransmitter levels of serotonin.     

The trophic factors S-100beta and basic fibroblast growth factor are increased in the forebrain reactive astrocytes of adult callosotomized rat.

S-100 is a calcium-binding protein that is predominantly found in astrocytes of the central nervous system. In the present study, we investigated the temporal and spatial changes of S-100beta immunoreactivity after a stereotaxic mechanical lesion of the adult rat corpus callosum performed with an adjustable wire knife. Rats were killed 7, 14 and 28 days after surgery. S-100beta immunoreactivity was found within the cytoplasm and processes of quiescent putative astrocytes that were observed throughout the gray and white matters of the forebrain of sham-operated rats. Following callosotomy, the S-100beta immunoreactive profiles showed increased size and thick processes, as well as increased amount of S-100beta immunoreactivity. Unbiased stereologic analysis revealed a sustained and widespread increase of the Areal Fraction of S-100beta immunoreactive profiles in the medial and lateral regions of the white matter of callosotomized rats at the studied time-intervals. In the cerebral cortex of callosotomized rats, the estimated total number of S-100beta immunoreactive profiles was also increased 7 and 14 days after the lesion. Since the cellular and temporal changes in S-100beta immunoreactivity were closely similar to those described for basic fibroblast growth factor (bFGF) following brain lesions, we co-localized the S-100beta and bFGF immunoreactivities after callosotomy. bFGF immunoreactivity was found in the nuclei of S-100beta immunoreactive glial profiles throughout the forebrain regions of the sham-operated rats. bFGF immunoreactivity was increased in the nuclei of reactive S-100beta immunoreactive putative astrocytes in the forebrain white matter and in the cerebral cortex of callosotomized rats. These results indicate that after transection of the corpus callosum of adult rats, the reactive astrocytes may exert paracrine trophic actions through S-100beta and bFGF. Interactions between S-100beta and bFGF may be relevant to the events related to neuronal maintenance and repair following brain injury.