Modeling amyotrophic lateral sclerosis in hSOD1 transgenic swine.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that occurs in two clinically indistinguishable forms: sporadic (SALS) and familial (FALS), the latter linked to several gene mutations, mostly inheritable in a dominant manner. Nearly 20% of FALS forms are linked to mutations in the Cu/Zn superoxide dismutase (SOD1) gene. Research on ALS relies on transgenic models and particularly on mice carrying a glycine-to-alanine conversion at the 93rd codon (G93A) of the hSOD1 gene. Although G93A transgenic mice have been widely employed in clinical trials and basic research, doubts have been recently raised from numerous reliable sources about their suitability to faithfully reproduce human disease. Besides, the scientific community has already foreseen swine as an attractive and alternative model to nonhuman primates for modeling human diseases due to closer anatomical, physiological and biochemical features of swine rather than rodents to humans. On this basis, we have produced the first swine ALS model by in vitro transfection of cultured somatic cells combined with somatic cell nuclear transfer (SCNT). To achieve this goal we developed a SOD1(G93A) (superoxide dismutase 1 mutated in Gly93-Ala) vector, capable of promoting a high and stable transgene expression in primary porcine adult male fibroblasts (PAF). After transfection, clonal selection and transgene expression level assessment, selected SOD1(G93A) PAF colonies were used as nuclei donors in SCNT procedures. SOD1(G93A) embryos were transferred in recipient sows, and pregnancies developed to term. A total of 5 piglets survived artificial hand raising and weaning and developed normally, reaching adulthood. Preliminary analysis revealed transgene integration and hSOD1(G93A) expression in swine tissues and 360° phenotypical characterization is ongoing. We believe that our SOD1(G93A) swine would provide an essential bridge between the fundamental work done in rodent models and the reality of treating ALS.

Rat brain serotonin neurones that express neuronal nitric oxide synthase have increased sensitivity to the substituted amphetamine serotonin toxins 3,4-methylenedioxymethamphetamine and p-chloroamphetamine.

Substituted amphetamines such as p-chloroamphetamine and the abused drug methylenedioxymethamphetamine cause selective destruction of serotonin axons in rats, by unknown mechanisms. Since some serotonin neurones also express neuronal nitric oxide synthase, which has been implicated in neurotoxicity, the present study was undertaken to determine whether nitric oxide synthase expressing serotonin neurones are selectively vulnerable to methylenedioxymethamphetamine or p-chloroamphetamine. Using double-labeling immunocytochemistry and double in situ hybridization for nitric oxide synthase and the serotonin transporter, it was confirmed that about two thirds of serotonergic cell bodies in the dorsal raphé nucleus expressed nitric oxide synthase, however few if any serotonin transporter immunoreactive axons in striatum expressed nitric oxide synthase at detectable levels. Methylenedioxymethamphetamine (30 mg/kg) or p-chloroamphetamine (2 x 10 mg/kg) was administered to Sprague-Dawley rats, and 7 days after drug administration there were modest decreases in the levels of serotonin transporter protein in frontal cortex, and striatum using Western blotting, even though axonal loss could be clearly seen by immunostaining. p-Chloroamphetamine or methylenedioxymethamphetamine administration did not alter the level of nitric oxide synthase in striatum or frontal cortex, determined by Western blotting. Analysis of serotonin neuronal cell bodies 7 days after p-chloroamphetamine treatment, revealed a net down-regulation of serotonin transporter mRNA levels, and a profound change in expression of nitric oxide synthase, with 33% of serotonin transporter mRNA positive cells containing nitric oxide synthase mRNA, compared with 65% in control animals. Altogether these results support the hypothesis that serotonin neurones which express nitric oxide synthase are most vulnerable to substituted amphetamine toxicity, supporting the concept that the selective vulnerability of serotonin neurones has a molecular basis.

Deprivation of growth hormone-releasing hormone early in the rat's neonatal life permanently affects somatotropic function.

This work investigated in rats whether passive immunization against the endogenous GHRF in the early postnatal period led to permanent alterations of somatotropic function, similar to those observed in several human growth disorders, e.g. constitutional growth delay (CGD). On postnatal days 1, 2, 4, 6, 8, and 10, rats were given an anti-GHRF-serum (GHRH-Ab, 100 microliters/rat, sc) and were tested 1, 30, and 60 days after this treatment for basal and GHRH-stimulated GH secretion both in vivo and in vitro. GHRH-Ab reduced both basal and GHRF-stimulated GH secretion at all intervals and induced marked and chronic impairment of growth rate. The following differences were observed in the GHRH-Ab treated rats compared to normal rabbit serum-treated controls: 1) GH biosynthesis (incorporation of L-[3H]leucine into the electrophoretic band of GH): reduction of about 70%, 1 day but not 30 days after treatment; 2) Pituitary weight: significant reduction in absolute weight (30-40%) at all posttreatment intervals, and relative weight, 1 and 30 days after treatment. 3) Pituitary GH concentration: significant reduction in GH content (about 40%) but not concentration, at all posttreatment intervals; 4) Percentage of somatotrophs (immunocytochemistry): about 40% reduction 1 day, but not 30 and 60 days after treatment; 5) Hypothalamic somatostatin messenger RNA (mRNA) levels in situ hybridization): selective reduction (40%) in the periventricular nucleus 1 day but not 30 days after treatment; 6) Hypothalamic somatostatin cell number (immunocytochemistry): no significant changes in any hypothalamic area at any interval; 7) Pituitary somatostatin binding (in situ autoradiography): significant reduction, 1 day and 30 days after treatment; 8) Somatostatin inhibition of GH release "in vitro": somatostatin effect on GH release was reduced 30 days after treatment. These and previous data indicate that: 1) Transient deprivation of GHRF in the immediate postnatal period of the rat leads to permanent impairment of growth rate and somatotropic function; 2) GHRF deficiency itself or through reduction of GH secretion impairs somatostatin functions temporarily in the hypothalamus and permanently in the pituitary; 3) This rat model may mimic some forms of growth disorders in humans and holds promise as useful tools for investigating the underlying pathophysiological mechanisms.

Distribution of GAP-43 mRNA in the adult rat brain.

Regional distribution of gene expression of the axonal growth-associated protein, GAP-43, was studied in adult rat brains by in situ hybridization autoradiography to determine the features of mature neuronal populations that synthesize GAP-43 protein. Such synthesis appears to correlate with axonal growth during maturation and regrowth after axotomy. In most adult neurons, the sharp decline in GAP-43 gene expression implies a reduced capacity for axonal growth. Neurons capable of extending axonal knobs in the absence of injury may indicate a "plasticity" underlying dynamic processes of interaction between neurons and their synaptic targets. Antisense and sense (control) riboprobes were used on serial sections in the three principal axes, and the magnitude of hybridization signal was examined to determine regional patterns. GAP-43 mRNA levels are pronounced in diverse neuronal groups including the locus coeruleus, raphé nn., dopaminergic nigral and ventral tegmental nn., mitral cells, hippocampal CA3, inferior olivary n., vagal motor n. and other parasympathetic preganglionic neurons, select thalamic midline and intralaminar nn., several specific nn. of the hypothalamus and basal forebrain, the granular layer of cerebellar cortex, the infragranular neocortex, and the granular olfactory paleocortex; there is a substantial range in the magnitude of expression. Regions revealing minimal signal include most thalamic sensory relay nuclei, the granule neurons of the olfactory bulb and dentate gyrus, and the caudate and putamen. Possible concomitants of GAP-43 expression include regulation of ion flux and neurotransmitter release. Those neurons with long, extensively dispersed and numerous synaptic connections display the strongest signals and may possess the greatest propensity for continuous growth and turnover of their axon terminals, in contrast to short-axon and specific projection neurons exhibiting minimal levels. These data may enable inferring which populations display normal or experimentally induced axonal growth.

Developmental and plasticity-related differential expression of two SNAP-25 isoforms in the rat brain.

In this article we study the relationship between the expression pattern of two recently identified isoforms of the 25-kD synaptosomal-associated protein (SNAP-25a and SNAP-25b) and the morphological changes inherent to neuronal plasticity during development and kainic acid treatment. SNAP-25 has been involved in vescicle fusion in the nerve terminal, and most likely participates in different membrane fusion-related processes, such as those involved in neurotransmitter release and axonal growth. In the adult brain, SNAP-25b expression exceeded SNAP-25a in distribution and intensity, being present in most brain structures . Moderate or high levels of SNAP-25a hybridization signal were found in neurons of the olfactory bulb, the layer Va of the frontal and parietal cortices, the piriform cortex, the subiculum and the hippocampal CA4 field, the substantia nigra/pars compacta, and the pineal gland, partially overlapping SNAP-25b mRNA distribution. In restricted regions of cerebral cortex, thalamus, mammillary bodies, substantia nigra, and pineal glands the two isoforms were distributed in reciprocal fashion. During development SNAP-25a mRNA was the predominant isoform, whereas SNAP-25b expression increased postnatally. The early expression of SNAP-25a in the embryo and the decrease after P21 is suggestive of a potential involvement of this isoform in axonal growth and/or synaptogenesis. This conclusion is indirectly supported by the observation that SNAP-25a mRNA, but not SNAP-25b mRNA, was upregulated in the granule cells of the adult dentate gyrus 48 hours after kainate-induced neurotoxic damage of the hippocampal CA3-CA4 regions. Increase of SNAP-25 immunoreactivity was observed as early as 4 days after kainate injection within the mossy fiber terminals of the CA3 region, and in the newly formed mossy fiber aberrant terminals of the supragranular layer. These data suggest an isoform-specific role of SNAP-25 in neural plasticity.

Evidence that central 5-HT2 receptors do not play an important role in the anorectic activity of D-fenfluramine in the rat.

To gain information on the role of central 5-HT2 receptors in the reduction of food intake caused by D-fenfluramine in rats, different intraperitoneal doses of metergoline, a non-selective 5-HT receptor antagonist and ritanserin, a selective 5-HT2 receptor antagonist, were compared for their ability (a) to antagonize the anorectic effect of D-fenfluramine; (b) to occupy central 5-HT2 receptors in vivo (measured by the binding of [3H]spiperone in the frontal cortex) and (c) to affect the concentrations of D-fenfluramine and its active metabolite, D-norfenfluramine in brain. Metergoline dose-dependently reduced the effect of D-fenfluramine (2.5 mg/kg i.p.) on food intake, with complete antagonism at 1 mg/kg, a dose which occupies about 50% of cortical 5-HT2 receptors. Ritanserin, at a dose (0.5 mg/kg) causing 50% occupation of 5-HT2 receptors, had no effect on anorexia induced by D-fenfluramine and only partially prevented it at doses which caused maximum occupation of 5-HT2 receptors (1-2 mg/kg). Unlike 1 mg/kg metergoline, 1 mg/kg ritanserin significantly reduced the concentrations of D-norfenfluramine in the frontal cortex and hypothalamus of rats 30 min after injection of D-fenfluramine. The results suggest that 5-HT receptors, other than 5-HT2, possibly 5-HT1B, are involved in the anorectic effect of D-fenfluramine in food-deprived rats.

Intraregional variation in expression of serotonin transporter messenger RNA by 5-hydroxytryptamine neurons.

The distribution of the messenger RNA encoding the 5-hydroxytryptamine transporter was investigated in rat brain. 5-Hydroxytryptamine transporter messenger RNA was found exclusively in the B1-B9 cell groups containing the cell bodies of 5-hydroxytryptamine neurons. Combined in situ hybridization and 5-hydroxytryptamine immunocytochemistry demonstrated 5-hydroxytryptamine transporter gene expression in the majority of and exclusively in 5-hydroxytryptamine neurons. Cells differed in their levels of expression of 5-hydroxytryptamine transporter messenger RNA and 5-hydroxytryptamine immunofluorescence, but with a tight correlation between the two parameters. Image analysis of cells from B7, the dorsal raphe nucleus, and B8, the median raphe nucleus, revealed significant differences between groups in the mean cellular level of 5-hydroxytryptamine transporter gene expression. Cells in the ventromedial subdivision of B7 displayed higher levels of expression than cells in B8 or cells in the lateral wings of B7. There was also heterogeneity in the distribution of the cellular levels of expression for two other genes expressed by 5-hydroxytryptamine neurons: l-aromatic amino acid decarboxylase messenger RNA and tryptophan hydroxylase messenger RNA. However, the relative levels of expression of these two genes within the four regions studied differed from that of 5-hydroxytryptamine transporter messenger RNA. These results indicate intraregional differences between 5-hydroxytryptamine neurons with respect to 5-hydroxytryptamine transporter messenger RNA levels. Such differences may account for the differential sensitivity of 5-hydroxytryptamine neurons to cytotoxins.

GAP-43 mRNA localization in the rat hippocampus CA3 field.

Gene expression of the axonal growth-associated protein, GAP-43, has been studied in the adult rat brain by in situ hybridization histochemistry. This protein is synthesized at high levels in neuronal somata in immature and regenerating neurons, but after establishment of mature synaptic relations its synthesis generally declines sharply, thus providing a marker denoting propensity for exhibiting synaptic plasticity. Detailed examination of the distribution of mRNA for GAP-43 in rat hippocampus is selectively and robustly expressed in the pyramidal neurons of field CA3 and, to a lesser extent, the polymorph neurons of the hilus of the dentate gyrus. Additional hippocampal regions of moderate expression include the tenia tecta and the subicular and entorhinal fields, but CA1 and CA2 are strikingly lower in signal. The significance of this pattern of localization is considered in the context of the phosphorylation of GAP-43 and its role in influencing synaptic events underlying the establishment and maintenance of long-term potentiation and plasticity in the hippocampus.

Effect of d-fenfluramine and 5,7-dihydroxytryptamine on the levels of tryptophan hydroxylase and its mRNA in rat brain.

Repeated high doses of d-fenfluramine (dF; 10 mg/kg, i.p. twice daily for 4 days) markedly reduced serotonin (5-HT) concentrations in the hippocampus and striatum of rat brain up to 1 month after treatment, while tryptophan hydroxylase (TPH) levels were reduced only in the hippocampus 5 days after injection. Unlike dF, an intracerebroventricular (i.c.v.) injection of 5,7-dihydroxytryptamine (5,7-DHT 150 micrograms/20 microliters) induced a marked and long-lasting reduction of 5-HT and TPH in both brain regions. Thirty days after injection, 5,7-DHT, but not dF, markedly reduced the number of labelled neurons in the dorsal and ventral regions of the nucleus raphe dorsalis (NRD) and raised the levels of TPH mRNA in the spared neurons at all times examined. TPH mRNA levels were raised 5 and 15 days after dF treatment in the NDR suggesting that changes in the TPH gene expression or transcript stability result following 5-HT depletion. These data are in agreement with the suggestion that 5,7-DHT damages 5-HT nerve terminals and perikarya, but leave unanswered the question of the mechanism of the long-lasting reduction of 5-HT levels caused by high, repeated doses of dF.

Expression of amyloid precursor protein mRNAs in endothelial, neuronal and glial cells: modulation by interleukin-1.

The origin of beta-amyloid deposited in senile plaques in Alzheimer's disease (AD) is not known. We compared the expression of protein precursor of beta-amyloid (APP) in the cell types involved in plaque formation. The levels of APP mRNA were determined in primary rat neurons and glial cells in culture, human endothelial cells and in a murine brain-derived endothelial cell line. Northern blot analysis was performed using an APP cDNA probe to detect the general APP sequence and an oligonucleotide (40 mer) complementary to the sequence of the Kunitz protease inhibitor (APP-KPI). The APP mRNA transcripts were abundant in all three cell types. The highest level of APP, normalized to beta-actin mRNA content, was expressed in neurons, followed by glial cells, where the APP expression was similar (94%) while in endothelial cells was lower (53%). The proportion between APP-KPI mRNA and total APP mRNA was high in endothelial, intermediate in glial and low in neuronal cells. We compared the effects of exposure to interleukin-1 (IL-1), a cytokine involved in several biological processes and elevated in AD, on APP mRNA expression in neuronal, glial and endothelial cells. In human endothelial and in brain-derived murine endothelial cells we observed a similar increase (50%) of total APP mRNA or APP-KPI mRNA after treatment with human recombinant IL-1 beta. In neuronal cells, IL-1 (200 ng/ml) substantially increased APP mRNA (175%), detected with both probes. In glial cells, the expression of APP mRNA did not appear to be altered by IL-1 (50-400 ng/ml). The results suggest a role of IL-1 in the neuronal mechanisms related to beta-amyloid protein deposition in AD.

Increased tryptophan hydroxylase mRNA in raphe serotonergic neurons spared by 5,7-dihydroxytryptamine.

Neurons expressing the tryptophan hydroxylase (TPH) mRNA within the raphe nuclei of control rats showed a distribution similar to that observed using an antibody for TPH. Numerous packed cells expressing the TPH mRNA were observed in the ventral and dorsal zone of the nucleus raphe dorsalis (NDR) and in the pars dorsalis of the nucleus centralis superior (NCS) whereas fewer and more scattered neurons were found in the pars medialis of NCS. Five days after the intracerebroventricular injection of 5,7-dihydroxytryptamine (5,7-DHT), which markedly reduced the serotonin (5-HT) content in the hippocampus, caudate putamen and cortex, the hybridization signal had completely disappeared in the dorsal region of the NDR. In the ventromedial region, above and between the medial longitudinal fasciculus (MLF), which includes the pars dorsalis of NCS, there was a partial decrease of cell number and a marked increase of the grain density over spared neurons. No significant change was noted in the number of TPH-positive cells and hybridization signal in individual neurons of the pars medialis of NCS. Consistent with previous evidence of increased TPH activity in the residual 5-HT terminals, the present study shows that synthesis of the TPH mRNA may be augmented in some neurons surviving the lesion.

Selective up-regulation of protein kinase C epsilon in granule cells after kainic acid-induced seizures in rat.

Kainate-induced seizure activity causes persistent changes in the hippocampus that include synaptic reorganization and functional changes in the mossy fibers. Using in situ hybridization histochemistry, the expression of PKC alpha, PKC beta, PKC gamma, PKC delta and PKC epsilon mRNAs was investigated in the hippocampus of adult rats following seizures induced by a s.c. injection of kainic acid. In CA1 and CA3, we found a significant decrease in PKC gamma mRNA 1 day after kainic acid which persisted for a 2nd day in CA1. None of the other PKC isoform mRNAs were altered in CA1 or CA3. In granule cells, a significant up-regulation specific to PKC epsilon mRNA was observed. One week after kainic acid administration, a marked increase in PKC epsilon immunoreactivity was found that persisted 2 months after kainic acid administration. PKC epsilon immunoreactivity was found associated with mossy fibers projecting to the hilus of the dentate gyrus and to the stratum lucidum of the CA3 field and presumably with the newly sprouted mossy fibers projecting to the supragranular layer. These data provide the first evidence for a long-lasting increase of the PKC epsilon in the axons of granule cells caused by kainate-induced seizures and suggest that PKC epsilon may be involved in the functional and/or structural modifications of granule cells that occur after limbic seizures.

Androgen 5-alpha-reductase type 2 is highly expressed and active in rat spinal cord motor neurones.

Spinal cord motoneurones express high levels of androgen receptor. However, in responsive tissue, the effects of testosterone is often mediated by the more potent androgenic derivative 5-alpha-dihydrotestosterone (DHT). This compound is formed in androgen target cells by the enzyme 5-alpha-reductase. Two isoforms of the 5-alpha-reductase, with limited degree of homology, have been cloned, type 1 and type 2. The low affinity-constitutive type 1 isoenzyme is widely distributed in the body; the high affinity-androgen regulated 5-alpha-reductase type 2 is confined to androgen-dependent structures and shows a peculiar pH optimum at acidic values. We have previously shown that high levels of 5-alpha-reductase activity are detectable in rat spinal cord. Here, using reverse transcriptase-polymerase chain reaction, we show that both isoforms are expressed in the whole spinal cord of the rat. The enzymatic pH optimum measured in immortalized spinal cord motoneurones (NSC34) is typical of the type 2 isoenzyme. Using in situ hybridization technique, we found that 5-alpha-reductase type 2 is confined to the motoneuronal cells of the anterior horns of the rat spinal cord, the cells that also are known to express high levels of androgen receptor. Because of the close association of androgen receptor and 5-alpha alpha-reductase type 2, motoneuronal cells should be considered as target cells for androgens.

The role of different types of adrenergic receptors in pentylenetetrazol-induced seizures and the effect of di-n-propylacetate in the rat.

Selective depletion of forebrain noradrenaline has been shown to potentiate various types of experimentally induced seizures. This study was aimed at exploring the role of different types of adrenergic receptors in pentylenetetrazol (PTZ)-induced seizures in rats and the anticonvulsive effect of di-n-propylacetate (DPA). Piperoxane (10 and 20 mg/kg, IP) significantly potentiated PTZ-induced tonic seizures and mortality. Similar effects were observed after 6-hydroxydopamine (6-OHDA)-induced depletion of forebrain noradrenaline, whereas no effects were found in animals with depletion of spinal noradrenaline. Neither phenoxybenzamine (20 mg/kg, IP) nor prazosin (1 and 10 mg/kg, IP) nor propranolol (2 and 5 mg/kg, IP) modified tonic seizures and mortality caused by PTZ. Combined treatment with propranolol (5 mg/kg, IP) and prazosin (10 mg/kg, IP) had no effect either. Various agents used to increase central serotonin transmission (d-fenfluramine, 5 mg/kg, IP; quipazine, 10 mg/kg, IP; m-chlorophenylpiperazine, 3 mg/kg, IP) did not alter the effect of piperoxane on PTZ-induced seizures. None of the conditions used to diminish central adrenergic function significantly affected the inhibitory effect of DPA on tonic seizures and mortality caused by PTZ. Combined treatment with subthreshold doses of clonidine (0.1 mg/kg, IP) and DPA (75 mg/kg, IP) significantly reduced tonic seizures and mortality caused by PTZ. The data suggest that alpha 2 type adrenoceptors are involved in the control of PTZ-induced seizures in rats. The peculiarity of the role of these receptors in the effect of PTZ is discussed.

Further studies on the mechanism of serotonin-dependent anorexia in rats.

4-(3-Indolyl-2-ethyl) piperidine (LM 5008), 2-(1-piperazinyl) quinoline (quipazine), and metachlorophenylpiperazine (mCPP) were studied for their ability to affect serotonergic mechanisms in vitro. Their relative potency in inhibiting serotonin (5-HT) uptake in vivo and reducing food intake in rats was also examined. mCPP was very potent in displacing 3H-5-HT bound to brain membranes (IC50, 6.2 X 10(-7) M), followed by quipazine, which showed an IC50 of 3.8 X 10(-6) M. LM 5008 was the least effective with an IC50 of 3.6 X 10(-5) M. mCPP and quipazine were less potent than d-fenfluramine in releasing 14C-5-HT from brain synaptosomes, while LM 5008 caused no significant effects at a concentration of 10(-5) M. Conversely, both in vitro and in vivo studies on 5-HT uptake showed that LM 5008 was the most potent compound in inhibiting 5-HT uptake and mCPP the least potent. Since a 50% reduction of food intake was not reached even with a dose of LM 5008 27-times higher than the ED50 for inhibiting 5-HT uptake in vivo, it is suggested that even marked inhibition of 5-HT uptake at central synapses is not sufficient per se to trigger serotonin-dependent anorexia in the rat. Increased release and/or direct stimulation of post-synaptic receptors may be necessary to obtain this effect. This could be of interest for developing new agents which can cause anorexia by interacting with brain serotonin.

Cycloheximide inhibits kainic acid-induced GAP-43 mRNA in dentate granule cells in rats.

We have previously shown that kainic acid-induced seizures in adult rats caused an up-regulation of GAP-43 mRNA in the granule cells of the hippocampus, suggesting an involvement of this protein in the kainic acid-induced sprouting of mossy fibres. To determine whether this effect was dependent on the synthesis of proteins activated under these experimental conditions we examined the effect of cycloheximide, a protein synthesis inhibitor, on kainic acid-induced GAP-43 mRNA. Cycloheximide, injected s.c. 2 h but not 8 h after kainic acid, markedly reduced the increased expression of GAP-43 mRNA in granule cells. These results suggest that a rapid mechanism involving new protein synthesis is activated by kainic acid to induce GAP-43 in the granule cells and possibly trigger the structural remodeling of mossy fibres.

Ultrastructural immunolocalization of GAP-43 in the sprouted mossy fibres of kainic acid lesioned rats.

Kainic acid (KA)-induced seizures in adult rats have been reported to cause sprouting of mossy fibres in the inner molecular layer (IML) of the dentate gyrus. In the present study, using electron microscopic immunostaining for GAP-43 we found that 3 months after KA treatment, several GAP-43 positive terminals in the IML showed structural characteristics of mossy fibre boutons. No GAP-43-positive mossy fibre terminals were found in the normal projection areas of granule cells, thus indicating that newly synthesized GAP-43 is transported predominantly in the axonal branches actively undergoing remodelling. These results provide evidence of the involvement of GAP-43 in the structural remodelling of mossy fibres, and suggest a role of this protein in the functional activity of the sprouted mossy fibres as a consequence of KA-induced seizures.

Selective localization of mouse aldehyde oxidase mRNA in the choroid plexus and motor neurons.

Aldehyde oxidase (AO), a protein involved in the catabolism of catecholamines, is the product of a gene potentially responsible for one of the familial forms of the motor neuron disease, amyotrophic lateral sclerosis (ALS). Here, we report on the cloning of a partial cDNA coding for the mouse enzyme. Using this cDNA as a probe, we demonstrate that the AO transcript is expressed in the epithelial component of the choroid plexus. More importantly, in the gray matter, the mRNA is selectively localized in the large motor neurons of the nuclei of facial, motor trigemini and hypoglossus nerves and in the motor neurons of the anterior horns of the spinal cord. This localization is consistent with a possible role of AO in the pathogenesis of ALS.

A simplified procedure for the physical development of the sulphide silver method to reveal synaptic zinc in combination with immunocytochemistry at light and electron microscopy.

The pool of zinc present in excitatory synaptic terminals in normal and pathological conditions (for instance the status epilepticus induced by kainic acid) can be stained by a silver sulphide method followed by physical development of the insoluble zinc-sulphide complexes. In this study we applied a previously described simple and rapid developing procedure that reveals synaptic zinc, to the study of normal and pathological hippocampi and combined it with pre and postembedding immunocytochemical methods to detect different antigens. Normal and kainic acid-treated rats were perfused with fixative solutions containing sodium sulphide and 50 microm-thick vibratome sections of the hippocampi were incubated in a commercial developing solution (IntenSE M, Amersham). The developed vibratome sections were then (1) mounted for light microscopy or osmicated and epon-embedded for electron microscopy; or (2) processed for the preembedding immunoenzymatic detection of various antigens (GABA, parvalbumin, calbindin) with light and electron microscopy. Thin sections from epon-embedded samples were also processed for the postembedding immunogold localization of glutamate. This very simple and rapid procedure gives rise to zinc-specific staining, comparable to that obtained with classical developing methods and good preservation of both antigenicity and ultrastructure. It is therefore possible to detect, in the same thick or thin section, zinc reaction product and different antigens.