Myelin-Independent Therapeutic Potential of Canine Glial-Restricted Progenitors Transplanted in Mouse Model of Dysmyelinating Disease

BACKGROUND

Dysfunction of glia contributes to the deterioration of the central nervous system in a wide array of neurological disorders, thus global replacement of glia is very attractive. Human glial-restricted precursors (hGRPs) transplanted intraventricularly into neonatal mice extensively migrated and rescued the lifespan in half of the studied mice, whereas mouse GRPs (mGRPs) presented no therapeutic benefit. We studied in the same experimental setting canine GRPs (cGRP) to determine whether their therapeutic potential falls between hGRPs and mGRPs. Additional motivation for the selection of cGRPs was a potential for use in veterinary medicine.

METHODS

cGRPs were extracted from the brain of dog fetuses. The cells were transplanted into the anterior or posterior aspect of the lateral ventricle (LV) of neonatal, immunodeficient, dysmyelinated mice (Mbpshi, Rag2 KO; shiv/rag2). Outcome measures included early cell biodistribution, animal survival and myelination assessed with MRI, immunohistochemistry and electron microscopy.

RESULTS

Grafting of cGRP into posterior LV significantly extended animal survival, whereas no benefit was observed after anterior LV transplantation. In contrast, myelination of the corpus callosum was more prominent in anteriorly transplanted animals.

CONCLUSIONS

The extended survival of animals after transplantation of cGRPs could be explained by the vicinity of the transplant near the brain stem.

SOD1/Rag2 Mice with Low Copy Number of SOD1 Gene as a New Long-Living Immunodeficient Model of ALS

The most recent research concerning amyotrophic lateral sclerosis (ALS) emphasizes the role of glia in disease development. Thus, one can suspect that the effective therapeutic strategy in treatment of ALS would be replacement of defective glia. One of the basic problems with human glial progenitors (hGRPs) replacement strategies is the time needed for the cells to become fully functional in vivo. The lifespan of most popular high copy number SOD1 mutant mice might be too short to acknowledge benefits of transplanted cells. We focused on developing immunodeficient rag2-/- model of ALS with lower number of transgene copies and longer lifespan. The obtained hSOD1/rag2 double mutant mice have been characterized. QPCR analysis revealed that copy number of hSOD1 transgene varied in our colony (4-8 copies). The difference in transgene copy number may be translated to significant impact on the lifespan. The death of long- and short-living hSOD1/rag2 mice is preceded by muscular weakness as early as one month before death. Importantly, based on magnetic resonance imaging we identified that mutant mice demonstrated abnormalities within the medullar motor nuclei. To conclude, we developed long-living double mutant hSOD1/rag2 mice, which could be a promising model for testing therapeutic utility of human stem cells.

Hydrogel-based scaffolds to support intrathecal stem cell transplantation as a gateway to the spinal cord: clinical needs, biomaterials, and imaging technologies

The prospects for cell replacement in spinal cord diseases are impeded by inefficient stem cell delivery. The deep location of the spinal cord and complex surgical access, as well as densely packed vital structures, question the feasibility of the widespread use of multiple spinal cord punctures to inject stem cells. Disorders characterized by disseminated pathology are particularly appealing for the distribution of cells globally throughout the spinal cord in a minimally invasive fashion. The intrathecal space, with access to a relatively large surface area along the spinal cord, is an attractive route for global stem cell delivery, and, indeed, is highly promising, but the success of this approach relies on the ability of cells (1) to survive in the cerebrospinal fluid (CSF), (2) to adhere to the spinal cord surface, and (3) to migrate, ultimately, into the parenchyma. Intrathecal infusion of cell suspension, however, has been insufficient and we postulate that embedding transplanted cells within hydrogel scaffolds will facilitate reaching these goals. In this review, we focus on practical considerations that render the intrathecal approach clinically viable, and then discuss the characteristics of various biomaterials that are suitable to serve as scaffolds. We also propose strategies to modulate the local microenvironment with nanoparticle carriers to improve the functionality of cellular grafts. Finally, we provide an overview of imaging modalities for in vivo monitoring and characterization of biomaterials and stem cells. This comprehensive review should serve as a guide for those planning preclinical and clinical studies on intrathecal stem cell transplantation.

Unusual cis and trans architecture of dihydrofunctional double-decker shaped silsesquioxane and synthesis of its ethyl bridged π-conjugated arene derivatives

An original family of well-defined molecular and macromolecular double-decker silsesquioxane derivatives with ethyl bridged π-conjugated arenes is obtained via hydrosilylation reaction.

Unusual emission properties of the selected organosilicon compounds containing a styryl-carbazole chromophore: inversion of the singlet excited states

The presence of the silicon atom in a trimethylsilyl-styryl-carbazole derivative induced the inversion of the lowest excited states in polar solvents.

An efficient catalytic synthesis and characterization of new styryl-ferrocenes and their trans-π-conjugated organosilicon materials

A selective and efficient catalytic method for the synthesis of new styryl-π-conjugated silyl-ferrocenes in a stereoselective manner is presented.

Synthesis and characterization of functionalized molecular and macromolecular double-decker silsesquioxane systems

Synthesis and characterization of new, molecular and macromolecular DDSQ-based compounds functionalized by substituted styrenes and distyrylarenes (also with heteroatoms) in a stereoselective manner is presented.

Ceramide galactosyltransferase (UGT8) is a molecular marker of breast cancer malignancy and lung metastases

BACKGROUND

It was shown recently on the level of gene expression that UGT8, coding UDP-galactose:ceramide galactosyltransferase, is one of six genes whose elevated expression correlated with a significantly increased the risk of lung metastases in breast cancer patients. In this study primary tumours and their lung metastases as well as breast cancer cell lines were analysed for UGT8 expression at the protein level.

METHODS

Expression of UGT8 in breast cancer tissue specimens and breast cancer cell lines was analysed using IHC, real-time PCR and Western blotting.

RESULTS

Comparison of the average values of the reaction intensities (IRS scale) showed a significant difference in UGT8 expression between (1) primary and metastatic tumours (Mann-Whitney U, P<0.05), (2) tumours of malignancy grades G3 and G2 (Mann-Whitney U, P<0.01) as well as G3 and G1 (Mann-Whitney U, P<0.001) and (3) node-positive and node-negative tumours (Mann-Whitney U, P<0.001). The predictive ability of increased expression of UGT8 was validated at the mRNA level in three independent cohorts of breast cancer patients (721). Similarly, breast cancer cell lines with the 'luminal epithelial-like' phenotype did not express or weakly expressed UGT8, in contrast to malignant, 'mesenchymal-like,' cells forming metastases in nude mice.

CONCLUSION

Our data suggest that UGT8 is a significant index of tumour aggressiveness and a potential marker for the prognostic evaluation of lung metastases in breast cancer.

Evidence for a critical role of entorhinal cortex at pre-exposure for latent inhibition disruption in rats

Latent inhibition (LI), that is the decrease in conditioned response induced by the repeated nonreinforced pre-exposures to the to-be-conditioned stimulus, is disrupted by entorhinal cortex (EC) lesions. The mechanism involved in this disruption is unknown, and in particular the experimental stage (pre-exposure or conditioning) at which the integrity of EC is necessary has to be determined. The purpose of this study was to address this issue by using reversible inactivation of the EC by local micro-infusion of tetrodotoxin (TTX). TTX was infused either before the pre-exposure phase, before the conditioning phase, or before both phases. LI was unaffected in rats that received TTX before conditioning or before both pre-exposure and conditioning. In contrast, LI was disrupted in rats that received TTX before pre-exposure only. These results are discussed in the framework of LI models.

Environmental enrichment increases responding to contextual cues but decreases overall conditioned fear in the rat

This study aimed at investigating the effects of environmental enrichment on various aspects of contextual processing in adult female rats. In experiment 1, simple conditioning was studied using either a training procedure allowing overshadowing of the contextual cues by signalling footshock with a discrete tone or a training procedure allowing a reduction of this overshadowing by explicitly unpairing the footshock and the tone. In experiment 2, contextual discrimination and contextual occasion-setting were assessed. Rats were daily exposed to two different contexts. In one context, a footshock was delivered 30s after the offset of a tone, whereas in the other context the same tone was presented alone. Experiment 3 examined familiarization to a new context. Experiment 1 showed that environmental enrichment reduced the overshadowing of contextual cues by the tone and also reduced freezing to the more predictive cue according to the training procedure used. Experiment 2 showed that environmental enrichment increased the ability of rats to discriminate two contexts. Experiment 3 showed that enriched rats familiarized faster to a new context than standard rats. Taken together, these results suggest that environmental enrichment in adult rats enhances learning about contextual cues and reduces overall fear associated with aversive events.

Entorhinal cortex lesions disrupt fear conditioning to background context but spare fear conditioning to a tone in the rat

Recent studies have shown that the integrity of the entorhinal cortex (EC) is not required for simple contextual conditioning. In background contextual conditioning, i.e., when a phasic cue is present during training, the involvement of the EC is still a matter of debate. Therefore, the present work further examines whether the EC is required for background contextual conditioning using a tone as the phasic cue. Rats sustaining either excitotoxic lesions of the EC or sham-lesions were trained with one of two procedures differing with respect to the predictive value of the tone: a paired procedure in which the tone perfectly predicts shock occurrence and overshadows context, and an unpaired procedure in which the predictive value of the tone is reduced. Conditioned fear was assessed by freezing responses during conditioning, reexposure to the training context, and reexposure to the tone in a new context. Postshock freezing was reduced in rats with entorhinal lesions. In all rats trained with the paired procedure, freezing to the context was low and freezing to the tone was high, suggesting that the tone has overshadowed the context during the conditioning session. The reverse pattern was observed with the unpaired procedure in sham-operated rats. In rats with entorhinal lesions trained with the unpaired procedure, freezing responses to the context was markedly reduced. In a new context, however, entorhinal-lesioned rats showed higher freezing scores than those of sham-lesioned rats. Freezing to the tone was unaffected by the lesion irrespective of the tone's predictive value. As a whole, these results support the notion that the EC is required for normal background contextual freezing.

Systemic or intra-accumbens injection of D-amphetamine delays habituation to a tone stimulus in rats

Dopamine release within the nucleus accumbens shell is suggested to control the salience of environmental stimuli, and previous research has shown that the indirect dopamine agonist D-amphetamine can alter the salience of both aversive and neutral stimuli. In experiment 1, the effect of systemic injection of D-amphetamine (0.5, 1 mg/kg) on fear conditioning to a tone was assessed in an 'off-baseline' conditioned suppression procedure using several footshock intensities. Although the effects of amphetamine on conditioning were unclear, the results indicated a deficit of simple tone habituation in amphetamine-treated rats. In experiment 2, habituation of the orienting reaction to a tone was assessed by the progressive reduction of lick suppression upon repeated presentation of the auditory stimulus. D-Amphetamine delayed tone habituation, whether administered systemically (0.5, 1 mg/kg) or into the nucleus accumbens shell (3, 10 microg/0.5 microl). These data are consistent with electrophysiological and neurochemical data demonstrating the role of nucleus accumbens dopamine in novelty processing. The relevance of the data to latent inhibition is discussed.

Bilateral lesions of the entorhinal cortex differentially modify haloperidol- and olanzapine-induced c-fos mRNA expression in the rat forebrain

Lesions of the entorhinal cortex are now an accepted model for mimicking some of the neuropathological aspects of schizophrenia, since evidence has accumulated for the presence of cytoarchitectonic abnormalities within this cortex in schizophrenic patients. The present study was undertaken to address the functional consequences of bilateral entorhinal cortex lesions on antipsychotic-induced c-fos expression. After a 15-day recovery period, the effect of a typical antipsychotic, haloperidol (1 mg/kg), on c-fos mRNA expression was compared with that of an atypical one, olanzapine (10 mg/kg), in both sham-lesioned and entorhinal cortex-lesioned rats. In sham-lesioned rats, both haloperidol and olanzapine induced c-fos expression in the caudal cingulate cortex, dorsomedial and dorsolateral caudate-putamen, nucleus accumbens core and shell and lateral septum. In addition, olanzapine, but not haloperidol, increased c-fos expression within the central amygdala. In entorhinal cortex-lesioned rats, haloperidol-induced c-fos expression was markedly reduced in most areas. In contrast, the olanzapine-induced c-fos expression was not altered in the nucleus accumbens shell and lateral septum of the lesioned rats. These findings reveal that entorhinal cortex lesions affect c-fos expression in a compound- and regional-dependent manner. Our results further emphasize the importance of the exploration of the mechanisms of action of antipsychotic drugs in the context of an associated cortical pathology.

Cholecystokinin stimulates aldosterone secretion from dispersed rat zona glomerulosa cells, acting through cholecystokinin receptors 1 and 2 coupled with the adenylate cyclase-dependent cascade

Cholecystokinin is a regulatory peptide, that acts through two subtypes of receptors, 1 and 2. RT-PCR demonstrated the expression of both cholecystokinin receptors 1 and 2 genes in the zona glomerulosa, but not the zona fasciculata-reticularis, of rat adrenals. Autoradiography demonstrated the presence of abundant [(125)I]cholecystokinin-binding sites in the zona glomerulosa, but not the zona fasciculata-reticularis, which were displaced by both cholecystokinin receptor 1- and 2-selective antagonists (cholecystokinin 1-A and 2-A). Cholecystokinin increased basal aldosterone secretion from dispersed zona glomerulosa cells without affecting corticosterone secretion from zona fasciculata-reticularis cells. The aldosterone response to cholecystokinin was blunted by cholecystokinin 1-A and 2-A, which when added together abolished it. ACTH-stimulated aldosterone production was not affected by cholecystokinin; in contrast, cholecystokinin potentiated aldosterone response to both angiotensin II and K(+). Cholecystokinin enhanced cAMP, but not IP(3), release by dispersed zona glomerulosa cells. The aldosterone response to cholecystokinin was abolished by the adenylate cyclase inhibitor SQ-22536 and the PKA inhibitor H-89, but not by either the PLC inhibitor U-73122 or the PKC inhibitor calphostin C. In conclusion, our study provides evidence that cholecystokinin, acting through cholecystokinin receptors 1 and 2 coupled with the adenylate cyclase/PKA cascade, exerts a sizeable secretagogue action on rat zona glomerulosa cells.

Prolonged cerebellin administration inhibits the growth, but enhances steroidogenic capacity of rat adrenal cortex

Cerebellin is a 16-amino acid peptide, that has been previously found to acutely stimulate steroid secretion from rat adrenal cortex in vivo and in vitro. We have investigated the effects of a prolonged cerebellin treatment (daily injections of 15 nmoles/kg for 6 consecutive days) on the growth and secretion of rat adrenal cortex. Cerebellin lowered adrenal weight, and morphometry showed that this was due to the decrease in the volume of each adrenocortical zone exclusively ensuing from the reduction in the number of its parenchymal cells. Cerebellin did not alter plasma concentration of ACTH, but it raised the levels of circulating aldosterone and corticosterone. The conclusion is drawn that cerebellin chronic administration evokes a marked hypoplastic atrophy of rat adrenocortical cells, that is coupled with an enhanced ACTH-independent steroidogenic capacity of the remaining parenchymal cells.

Leptin prolonged administration inhibits the growth and glucocorticoid secretion of rat adrenal cortex

Leptin is an adipose-tissue secreted hormone, that acts to decrease caloric intake and to increase energy expenditure. Some of the leptin effects on the energy balance are known to be mediated by the hypothalamo-pituitary-adrenal (HPA) axis, but the role of this cytokine in the regulation of the growth and steroidogenic capacity of adrenal cortex is still controversial. Therefore, the present study was designed to explore the long-term effects of native leptin[1-147] and its biologically active fragment leptin[116-130] (6 daily subcutaneous injection of 20 nmol/kg) on the rat HPA axis. Leptin[1-147] and leptin[116-130] caused a significant adrenal atrophy, which was mainly due to the decrease in the volume of zona fasciculata (ZF) and in the number of its parenchymal cells. Both leptins provoked a marked drop in the plasma concentrations of ACTH and corticosterone, the main hormone produced by ZF cells. The effects of leptin[116-130] were more intense than those of leptin[1-147]. Leptin[1-147], but not its fragment, evoked a clear-cut rise in the plasma concentration of aldosterone. Collectively, these findings indicate that prolonged leptin administration, by inhibiting pituitary ACTH release, exerts a potent suppressive action on the growth and glucocorticoid secretory capacity of the adrenal cortex in the rat. The mechanism(s) underlying the aldosterone secretagogue action of native leptin remain(s) to be investigated.

GABA and muscimol as reversible inactivation tools in learning and memory

Reversible inactivation of brain areas is a useful method for inferring brain-behavior relationships. Infusion of GABA or of the GABA receptor agonist muscimol is considered one interesting reversible inactivation method because it may not affect fibers of passage and may therefore be compared to axon-sparing types of lesions. This article reviews the data obtained with this method in learning and memory experiments. A critical analysis of data, collected in collaboration with Simon Brailowsky, with chronic GABA infusion is presented, together with an illustration of data obtained with muscimol-induced inactivation.

Entorhinal but not hippocampal or subicular lesions disrupt latent inhibition in rats

Latent inhibition (LI) is the deficit of conditioning resulting from repeated nonreinforced preexposure to a conditioned stimulus before its pairing with an unconditioned stimulus. There are cumulative data showing that large lesions of the hippocampal formation disrupt LI. However, the effects of selective lesions of the different components of the hippocampal formation have never been directly addressed in the same study and conditioning paradigm. The first experiment of the present study aimed at investigating the effects of excitotoxic lesions of the hippocampus, subiculum, or entorhinal cortex on LI in an "off-baseline"-conditioned emotional response procedure. Hippocampus or subiculum lesions had no effect on either LI or conditioning. In contrast, entorhinal cortex lesions disrupted LI without modifying conditioning. In Experiment 2, locomotor activity in a novel environment was assessed in the same rats. Whereas lesions of hippocampus increased locomotor activity, lesions of the subiculum or the entorhinal cortex were devoid of effect. Although both LI and habituation to novel environmental cues are thought to involve interactions between the hippocampal formation and the mesolimbic pathway, these results indicate a functional dissociation between the hippocampus and the entorhinal cortex.

Effects of neurotensin and bombesin on the secretory and proliferative activity of regenerating rat adrenal cortex

Neurotensin (NT) and bombesin (BM)-like peptides are known to be involved in the regulation of the rat hypothalamo-pituitary-adrenal axis. By using selective NT- and BM-receptor antagonists (NT-A and BM-A, respectively) we investigated whether endogenous NT and BM-like peptides play a role in the control of rat adrenal secretion and growth during enucleation-induced regeneration. At day 5 of regeneration, NT-A did not affect the plasma concentrations of aldosteronc (PAC) and corticosterone (PBC), but at day 8, it raised both PAC and PBC over the respective baseline value; the simultaneous administration of NT abolished this effect of NT-A. BM-A did not alter PAC and PBC at day 5 of regeneration, while at day 8 it enhanced PBC, an effect reversed by BM. NT-A did not alter mitotic index, and BM-A lowered it at both day 5 and day 8 of regeneration, an effect suppressed by the simultaneous administration of BM. Collectively, these findings allow us to draw the following conclusions: 1) endogenous NT and BM-like peptides influence adrenocortical regeneration in rats; 2) NT exerts a tonic inhibitory action on both aldosterone and corticosterone secretion, without affecting cell-proliferation rate; and 3) BM-like peptides exert a tonic suppressive effect on corticosterone production, coupled with a clear-cut stimulating effect on cell proliferation.

Effects of endothelin-1 on the rat pituitary-adrenocortical axis under basal and stressful conditions

Endothelins (ETs) and their receptor subtypes A and B (ETA and ETB) are expressed in the various components of the mammalian hypothalamo-pituitary-adrenal (HPA) axis, but their involvement in the functional regulation of HPA is controversial. To gain insight into this topic, we have investigated the effects of ET-1 and/or the specific antagonists of ETA and ETB receptors (BQ-123 and BQ-788, respectively) on the plasma concentrations of ACTH, corticosterone and aldosterone of non-stressed (control) and ether- or cold-stressed rats. The study of the effects of the administration of the two ET-receptor antagonists alone could provide informations about the possible action of endogenous ETs on the HPA axis. Exogenous ET-1 increased ACTH, corticosterone and aldosterone blood levels in control rats, as well as evoked a sizable enhancement of the HPA axis response to ether stress and a marked depression of the response to cold stress. BQ-123 and BQ-788 did not prevent the stimulatory effect of exogenous ET-1 in control rats, but when administered alone, raised the plasma concentrations of ACTH, corticosterone and aldosterone. Both ET-receptor antagonists magnified the HPA axis response to ether and cold stresses, but their effect was not counteracted by exogenous ET-1. Although very difficult to interpret, our present findings allow us to conclude that endogenous ETs play a role in the maintenance of the basal activity of rat HPA axis acting through ETA and ETB receptor subtypes, which are partially insensitive to BQ-123 and BQ-788. Conversely, the involvement of ETs in the modulation of the HPA axis responses to various stresses is very doubtful.

Effects of bombesin on the morphology and function of the rat adrenal cortex: comparison of the acute and chronic responses

The acute and chronic effects of bombesin (BM) on the structure and function of rat adrenal cortex were investigated by morphometric and radioimmunological techniques. An intraperitoneal bolus injection of 2 micrograms/rat BM markedly raised plasma corticosterone (B) concentration (PBC). The intraperitoneal BM infusion (1 microgram/rat.h-1) for 1, 2 or 4 days evoked a notable increase in the number of adrenocortical cells, without inducing apparent changes in either PBC or B output by adrenal quarters. Since proliferation and expression of specialized functions are mutually exclusive states of cells, our findings suggest that the conspicuous stimulation of adrenocortical-cell proliferation evoked by BM infusion may be responsible for the apparent lack of effect of this treatment on B secretion.

"Short-stops" in rats with fimbria-fornix lesions: evidence for change in the mobility gradient

Rats with damage to the hippocampal formation and allied structures are hyperactive in many test situations but the cause of this hyperactivity is not known. Here the activity of control rats and rats with fimbria-fornix lesions is documented in tests of overnight activity. Details of activity are then characterized from video recordings of behavior in an open field. Rats with fimbria-fornix lesions make significantly more stops of shorter duration and thus more individual trips than control rats but they do not differ in the distance traveled on individual trips or in travel speed. It is suggested that the main difference between fimbria-fornix rats and control rats is that when fimbria-fornix rats stop they remain "still" for shorter durations than do control rats. This finding is discussed in relation to a theory of locomotor/exploratory behavior, and in relation to its implications with respect to the performance of fimbria-fornix rats in studies of learning and memory.

Neurotensin stimulates the growth and secretion of rat adrenal zona glomerulosa

Within 2 days neurotensin (NT) and ACTH administrations markedly enhanced the average volume of zona glomerulosa (ZG) cells and plasma aldosterone concentration (PAC) in intact rats. In dexamethasone-treated rats, both NT and ACTH evoked a clearcut ZG-cell hypertrophy, but only NT was able to raise PAC. In conclusion, our findings indicate that NT is a potent stimulator of the growth and secretion of rat ZG in vivo, and suggest that the mechanism underlying this action of NT does not involve the well-known NT-induced stimulation of ACTH release.

Local cerebral glucose utilization during chronic infusion of GABA into the nucleus basalis magnocellularis of rats

The metabolic effects of gamma aminobutyric acid (GABA) unilaterally infused for 24 h into the nucleus basalis magnocellularis (NBM) of rats were studied using the 2-deoxyglucose method for measuring local cerebral metabolic rates for glucose (CMRglc). These results demonstrated that GABA infusion at the concentration of 100 micrograms.microliters-1 induced a strong ipsilateral depression in glucose utilization in the NBM and in some surrounding structures (e.g., the lateral hypothalamic area, thalamus, and amygdala) as well as in the major cortical targets of NBM neurons (i.e., the frontal, parietal, and temporal cortices). On an other hand, GABA infusion at the concentration of 10 micrograms.microliter-1 had no significant effect on cerebral metabolism compared to the saline-infused rats. Nevertheless, both GABA at the concentration of 10 micrograms.microliter-1 and saline induced a reduction of cerebral metabolism in the infused NBM, compared to the contralateral noninfused NBM. It was also demonstrated that saline pretreatment reduced the metabolic depression induced by GABA infusion at the highest concentration. When GABA was infused at the concentration of 100 micrograms.microliter-1, a slight reduction of CMRglc was observed in the hemisphere contralateral to the infused one, mainly in NBM target areas. In view of our previous behavioral data, these results suggest among others, that there is no necessary relationship between cerebral glucose metabolism and behavioral expression.

Cytophotometric analysis of magnocellular azure B-RNA and Feulgen-DNA following chronic GABA infusion into the nucleus basalis of rats

This investigation was undertaken to examine possible cytopathic effects of GABA infusion on nucleus basalis (NBM) magnocellular neurons. Sixty-three male Long-Evans rats received unilateral, intra-NBM infusions of either GABA100 (100 micrograms/microliters/h), GABA10 (10 micrograms/microliters/h), or ultrafiltered saline (1 microliter/h) for a period of 24 hours. Rats from each of these groups were sacrificed at either 24 hours, 48 hours or 8 days following initiation of infusions. The sham operated hemisphere of each rat served as a control for the infused hemisphere. After stoichiometric azure B-RNA and Feulgen-DNA staining of brain sections, scanning-integrating microdensitometry was used to quantify GABA-induced alterations in these well established indices of neuronal toxicity. These results provide evidence that the neurotoxic effects of 24 hours of 100 micrograms/microliters-h GABA infusion are manifested within 48 hours post-initiation of infusions. Although 24 hours of 10 micrograms/microliters-h GABA infusion suppressed NBM neuronal metabolism, the lower magnitude and duration of this effect signified an impending recovery. GABA infusion resulted in little if any NBM neuronal chromatin template impairment (i.e., reduced Feulgen-DNA reactivity), irrespective of the dosage employed and the delay prior to sacrifice.

Chronic infusion of GABA into the nucleus basalis magnocellularis or frontal cortex of rats: a behavioral and histological study

In order to determine the influence of the nucleus basalis magnocellularis (NBM) on the sensorimotor function of the frontal cortex (FCx) of the rat, GABA at various concentrations (10, 50 or 100 micrograms.microliters-1) was administered into these structures. GABA was infused for four consecutive days after which saline was infused for another four. On the contralateral side the order of administration was reversed. Each structure received GABA while its homologous on the contralateral side received saline. Before, during and after drug infusion, the animals were weighted and their performance in two non-reinforced behavioral tasks (beam walking and spontaneous rotation) was examined. When GABA was infused into the FCx, a dose-dependent and reversible sensorimotor deficit was observed along with a behavioral withdrawal syndrome upon GABA discontinuation. When GABA was administered into the NBM, a reversible sensorimotor deficit was observed only when GABA was infused at the highest concentration. In this case no behavioral changes were observed upon GABA discontinuation. Histologically, a gliosis was observed in the NBM in which GABA was infused at the two highest concentrations without saline pretreatment; these effects were not observed when GABA was infused without saline pretreatment into the FCx. In relation to our previous findings, these results suggest that i) the FCx is directly involved in the expression of sensorimotor functions, while the influence of the NBM on these functions appears only after severe subcortical damage, ii) a GABA withdrawal syndrome is observed following GABA administration in the FCx but not in the NBM, and iii) "tonic" effects of GABA are dose-related and partially dependent upon pretreatment conditions and the brain region infused.

Effect of bombesin on the structure and function of the rat adrenal cortex

Intact and dexamethasone-treated adult female Wistar rats were infused (Alzet osmotic minipumps) with bombesin (0.75 micrograms/rat per day) for 7 days. Bombesin depressed body weight and capacity of adrenal homogenate to secrete corticosterone; the latter effect was reflected in intact rats by a drop in serum corticosterone level. Bombesin had no effect on pituitary and serum adrenocorticotropic hormone (ACTH) concentration and serum aldosterone level. In intact animals, infusion of bombesin resulted in lowering of the number of parenchymal cells in adrenal cortex connected with the hypertrophy of glomerulosa and fasciculata cells. Moreover, bombesin lowered basal corticosterone secretion by isolated rat adrenocortical cells; however, neuropeptide applied did not change the response of isolated cells to ACTH stimulation. The data obtained clearly demonstrate inhibitory effect of bombesin on basal corticosterone secretion by the rat adrenal cortex.

Chronic infusion of GABA and saline into the nucleus basalis magnocellularis of rats: II. Cognitive impairments

In order to assess sensorimotor and/or cognitive modifications following chronic inhibition of nucleus basalis magnocellularis (NBM) neurons, rats trained in two radial maze paradigms (the classical version of the test and a modified version introducing a one-hour delay between the fourth and the fifth choice) received chronic infusion of gamma-aminobutyric acid (GABA) into the NBM area. GABA (10 and 50 micrograms/microliters/h) was infused for 3 days into the NBM contralateral to their preferred turning direction in the radial maze. Simultaneously, saline (NaCl 0.9%; 1 microliter/h) was infused into the contralateral NBM. GABA and saline infusions were alternated for the subsequent 3-day period. One week later, we investigated the rats' ability to learn a multiple trial passive avoidance task. At the dose of 50 micrograms/microliters, GABA infusion produced (1) a turning bias ipsilateral to the side first infused with GABA, (2) transitory cognitive impairments in radial maze tasks and (3) a deficit in the acquisition of the passive avoidance task. At the dose of 10 micrograms/microliters, the same behavioral deficits were observed except that (1) the turning bias was reversed by the contralateral GABA infusion and (2) cognitive impairments in the radial maze were observed only when a delay was inserted between the fourth and the fifth choice. Histologically, we found a dose-dependent gliosis in the NBM area first infused with GABA. These data suggest a reactivity of the NBM to GABAergic manipulations and the intervention of this structure in both sensorimotor and cognitive processes involved in the radial maze paradigms.

Chronic treatment with amitriptyline produces subsensitivity to the hypothermic effects of clonidine

1. Supersensitivity or up-regulation of presynaptic alpha 2-adrenoceptors may be involved in the pathogenesis of depression. 2. The authors used a thermoregulation paradigm to test the hypothesis that chronic treatment with a tricyclic antidepressant amitriptyline (AMI) produces subsensitivity to the hypothermic effects of the alpha 2 agonist clonidine. 3. Treatment with amitriptyline produced blunting of the hypothermic response to clonidine. 4. Subsensitivity persisted for at least 21 days--that point after the discontinuation of the tricyclic at which the animals were last challenged with clonidine. 5. These findings are consistent with previous reports that tricyclic antidepressants produce subsensitivity of alpha 2 adrenoceptors.

Stereologic studies on the adrenal cortex of 4-APP (4-amino-pyrazolopyrimidine)-induced lipoprotein-deficient rats

The effect of 4-APP (4-aminopyrazolopyrimidine), the compound reducing hepatic release of lipoproteins, on the rat adrenal cortex was studied by means of stereological methods. Within 3 days 4-APP resulted in a marked increase in the absolute and relative adrenal weights and markedly lowered plasma and adrenal total cholesterol concentration. 4-APP did not change the relative volume of individual adrenocortical zones, however significantly increased the volume in mm3 of the zona fasciculata (ZF) and reticularis (ZR) and of the entire cortex. The average volume of the ZF and ZR cells of 4-APP treated rats was markedly higher than in control rats while no difference was found in the zona glomerulosa (ZG) cell. In lipoprotein-deficient rats the number of adrenocortical cells within the entire cortex was similar to that observed in control rats. A marked increase in the number of mitoses in both, adrenocortical and endothelial cells suggests inhibitory action of 4-APP on the proliferative activity of these cells. The present study shows that 4-APP-induced changes in the rat adrenal cortex mainly depends upon the stimulatory action of that compound on ACTH secretion, however this adenine analogue also exerts a direct action on the adrenocortical cells.

Estradiol and melatonin effects on adrenal cortex of ovariectomized and pinealectomized rats

Studies on the effect of pinealectomy (PX) and melatonin on adrenal cortex of ovariectomized and estradiol replaced rats were performed. Neither PX nor melatonin replacement changed corticosterone output by adrenal homogenate, 11 beta-hydroxylase activity, liver corticosterone metabolism or serum corticosterone level, however, melatonin increased adrenal 5 alpha-reductase activity. On the other hand, PX of 14 months duration resulted in an increase in intraadrenal 5 alpha-reductase activity. PX did not modify estradiol effect on rat adrenal cortex, while concomitant estradiol-melatonin administration increased corticosterone output by adrenal homogenate. Stimulatory effect of estradiol on liver corticosterone metabolism was observed only in the presence of pineal gland or exogenous melatonin. In non of experiments, 45 nmole/ml of melatonin added into incubation medium stimulated adrenal 5 alpha-reductase activity. Obtained results cast doubt on a physiological role of melatonin in regulation of adrenocortical secretory activity in ovariectomized rats and suggest that estradiol effect on the adrenal cortex is not mediated by the pineal gland.

Sex differences in adrenocortical structure and function. XII. Stereologic studies of rat adrenal cortex in the course of maturation

This paper reports a stereological study of the cellular aspects of development of the adrenal cortex of male and female rats in the course of maturation. Rats of the Wistar strain were studied at weekly intervals from day 21 to day 77 of postnatal life. From day 42 homogenates of adrenals from female rats produced more corticosterone than homogenates from males of corresponding age. In the strain of rats studied sex differences in adrenal weight appeared at about day 49. From this day onward relative, and subsequently absolute adrenal weights were higher in females than in males. In the course of maturation the total volume of all adrenocortical zones gradually increased. From day 70 the zona glomerulosa and from day 49 the zona fasciculata were larger in female than in male rats, while no distinct sex difference was observed in the volume of the zona reticularis. The appearance of sex-related differences in the adrenal cortex depends mainly on changes in the zona fasciculata, the cells of which markedly increased in volume in female rats by comparison with males. The total number of all adrenocortical cells increased from ca 13 million on day 21 to ca 25 million on day 77 and at all intervals studied adrenal glands of male and female rats contained a similar number of parenchymal cells.

Sex dimorphism in the thyroid gland. III. Morphometric studies on the rat thyroid gland in the course of postnatal ontogenesis

At weekly intervals between 21 and 84 days of postnatal ontogenesis, on the thyroid glands of male and female rats morphometric studies were performed. The rate of body growth was similar in male and female rats between 21 and 42 days. Thereafter male rats are heavier than females. There were no differences in composition of particular histologic components studied in the thyroids of male and female rats between 21 and 35 days. From day 42 the volume fraction of colloid is lower in the male than female gland. Also from day 49 of postnatal ontogenesis the follicular cells are taller in male than in female thyroid gland. After reaching puberty in the female thyroid gland a gradual lowering of the volume fraction of epithelium and an increase in volume fraction of colloid are observed. Due to these changes epithelium/colloid ratio in female rats markedly declines between 42 and 84 days of postnatal ontogenesis while in the male rats this ratio is higher and does not show such a distinct decline.

Effect or partial hepatectomy on secretion and metabolism of corticosterone in the rat

Investigations on the interrelationship between the rate of hepatic corticosterone metabolism intraadrenal 5 alpha-steroid reductase activity were performed in the rat. As an experimental model partially hepatectomized animals were employed. Male rats were studied 24 hrs, 3 and 8 days post surgery and female 5 and 8 days after partial hepatectomy. In male and female rats, partial hepatectomy caused an increase in adrenal 5 alpha-steroid reductase activity, however, this effect was observed only in rats studied 8 days post surgery, These results suggest the participation of the liver in the regulation of hypothalamo-pituitary-adrenocortical axis and show that intraadrenal 5 alpha-steroid reductase may be involved in this regulatory system.

Investigations of anthelminthic activity and synthesis of new derivatives of perhydroazepine, perhydro-1,4-diazepine, perhydro-1,4-oxazepine and perhydro-1,5-oxazocine

Anthelminthic activity of new esters of 3,4,5-trimethoxybenzoic acid containing rests of the title heterocyclic amines has been determined. 3-(Perhydroazepinyl)-propyl ester 6 acts on enchytraeids in vitro 56-fold stronger than piperazine adipate, 2-(perhydroazepinyl)-ethyl ester 5 is the most effective in a therapy of mice infested with nematodes.