The antigen receptor complex on cord B lymphocytes

The neonatal immune system responds to a restricted range of antigens, producing largely IgM antibody of low affinity. Comparison of the components of the B-cell antigen receptor complex shows significantly elevated membrane levels of IgM in neonatal B cells, compared with adult cells. CD79, which acts as the signal transducer for membrane immunoglobulin, is elevated in parallel with IgM, while IgD is elevated to a lesser degree. CD19, CD21, CD22 and CD81, which are all involved in transmitting activation signals when immunoglobulin is engaged, are not elevated. CD32, which is involved in negative regulation of activation, is present at reduced levels on cord B cells. The elevation of B-cell membrane IgM persists during infancy. Neonatal B cells respond in vitro to interleukin-4 (IL-4) by further elevation of membrane IgM levels. The elevated level of membrane IgM may make neonatal B cells easier to trigger by low concentrations of antigen, but in vitro activation and immunoglobulin modulation experiments did not show significant differences between cord and adult B-cell responses to anti-IgM.

The Fas antigen (CD95) on human lymphoid cells: epitope analysis with ten antibodies

The expression of CD95 antigen was examined on adult and cord blood lymphocytes using a highly sensitive immunofluorescence/flow cytometric procedure. CD95 was expressed by the majority of circulating blood T cells in adults, and by a smaller proportion of CD4+ and CD8+ T cells in cord blood. The majority of circulating B cells did not react with seven CD95 antibodies, but three antibodies did stain B cells. In tonsil sections, CD95 was expressed throughout the tissue but germinal centres showed generally stronger staining than the surrounding follicular mantle and interfollicular areas. This was confirmed by flow cytometry, which showed expression preferentially on B cells with a germinal centre phenotype. Because different antibodies stained different proportions of B cells, CD95 epitopes were examined by inhibition, additive binding and protease susceptibility studies using a panel of ten CD95 antibodies. B cells apparently reacting selectively with CD95 antibodies were sorted and CD95 mRNA was reverse transcribed to cDNA and analyzed, in order to confirm the presence of CD95 in cells which reacted selectively and to explore the possible existence of CD95 isoforms. The major cDNA band was identical in the two populations. Inhibition of N-glycosylation suggested that the epitopes detected differentially could not be accounted for by differential N-glycosylation.

Reduced expression of the interleukin-2-receptor gamma chain on cord blood lymphocytes: relationship to functional immaturity of the neonatal immune response

Mutation of the interleukin-2 (IL-2) receptor gamma chain, which also serves as a component of the receptor complexes for IL-4, 7, 9 and 15, results in severe immune deficiency. We hypothesized that the immunological immaturity of healthy neonates might be associated with low levels of expression of this receptor molecule. Using monoclonal antibody and a highly sensitive immunofluorescence method, we showed that IL-2 receptor gamma chain is expressed at significantly lower levels on cord blood cells compared with adult cells. IL-2-dependent T-cell activation in vitro was reduced in cord blood cells compared with adult cells, but B-cell responses to IL-4 were not obviously impaired. The lower level of expression of the gamma chain and some other cytokine receptor chains may contribute to the immunological immaturity of the newborn, by selectively depressing particular immunological mechanisms.

Expression of cytokine receptors by human cord blood lymphocytes: comparison with adult blood lymphocytes

The expression of receptors for several cytokines (IL 2, IL-4, IL-6, IL-7, tumor necrosis factor, and interferon-gamma) was examined in human cord blood cells in comparison with adult blood cells. A previously described high sensitivity immunofluorescence procedure was used to render the low levels of receptor measurable. Cord blood lymphocytes expressed measurable levels of most cytokine receptors, but expression tended to be lower than in adult blood cells. Examination of different lymphocyte subpopulations revealed a complex pattern with some cell types expressing particular receptors equivalent to adult levels. Cord and adult blood monocytes expressed similar cytokine receptor profiles. Receptor expression in cord lymphocytes could be regulated by activation. The results provide indications as to the relative activities of different cytokines in the development of the immune system in the neonate.

Cytokine receptor expression in human lymphoid tissue: analysis by fluorescence microscopy

A highly-sensitive flourescence method, capable of detecting cytokine receptors present at low concentrations (around 100 molecules per cell) by flow cytometry, was adapted for use on tissue sections. This method was used to examine the expression of several cytokine receptors in lymphoid tissues. IL-2 receptors were distributed broadly, with higher concentrations in T cell areas. IL-1 receptor Type 1 was detected in T cell areas and in the follicular mantle, and was strongly expressed on vascular endothelium. IL-6 receptor was found at very low concentration, both within and outside germinal centres. The gp 130 molecule, which is involved in the functional receptor complex for IL-6 and several other cytokines, was present at higher concentrations, particularly in the germinal centre. Analysis of receptor expression in secondary lymphoid tissue provides evidence bearing on the physiological roles of cytokines, as these tissues contain cells at various stages of physiological activation located in well-defined functional zones.

IgE+ cells in the peripheral blood of atopic, nonatopic, and bee venom-hypersensitive individuals exhibit the phenotype of highly differentiated B cells

We have analyzed IgE+ cells in peripheral blood of atopic donors, donors hypersensitive to bee venom, and nonatopic control donors with two- and three-color flow cytometry. Although the percentage of IgE+ cells varied among these groups, the overall phenotypic patterns were similar. Most IgE+ cells do not display typical B-cell markers, such as CD19, CD20, and CD21. A significant proportion of these cells stain for CD38, indicating that they are more differentiated. IgE+ cells express Fc gamma RII and CD45RO, an isoform associated with an advanced level of differentiation. The majority of IgE+ cells do not coexpress other surface immunoglobulin isotypes. In the case of bee venom-hypersensitive donors, we have been able to identify a small population of IgE+ cells with a specificity for phospholipase A2, a major immunogenic component of bee venom. The phospholipase A2+ cells display a phenotype similar to that of the IgE+ cells.

Pharmacokinetics of nerve growth factor (NGF) following different routes of administration to adult rats

The suggested potential for therapeutic use of nerve growth factor (NGF) in the treatment of toxic and degenerative disorders of the nervous system indicates a need to determine its pharmacokinetics. To this end, murine NGF was administered to adult rats and multiple blood samples were withdrawn at intervals. NGF levels, determined in plasma samples by a two-site enzyme immunoassay, were used to determine the pharmacokinetics of NGF. These studies demonstrate that murine NGF has a distribution half-life of about 5.4 min and an elimination half-life of 2.3 h following intravenous injection. When administered by subcutaneous (sc) injection, the elimination half-life is prolonged to 4.5 h. Administration of NGF by sc continuous infusion, using mini-osmotic pumps, provides stable, dose-related levels of circulating NGF within few days from pump implantation. Upon removal of the pump, NGF levels show a rapid decay (t1/2 about 1.5 h) followed by a slow elimination phase (t1/2 about 150 h). These pharmacokinetic parameters might serve for selection of an appropriate administration route and dose regimen that would optimize schedule-dependent expression of NGF therapeutic activity.

Intracerebroventricular administration of nerve growth factor affects muscarinic cholinergic receptors in the cerebral cortex of neonatal rats

The repeated intracerebroventricular administration of nerve growth factor (5 micrograms/2.5 microliters) to neonatal rats induced the activation of choline acetyltransferase in forebrain cholinergic neurons that was paralleled by a concomitant change in the density of muscarinic cholinergic receptors in the cerebral cortex. The administration of nerve growth factor altered muscarinic binding sites in a biphasic fashion during postnatal development. A significant stimulation of the developmental increase in the density of muscarinic binding sites occurred in nerve growth factor-treated animals at days 2 and 3 after birth. Conversely, nerve growth factor induced a significant decrease in the receptor number at postnatal days 8 and 14. Muscarinic receptor number returned to control values after treatment, suggesting that nerve growth factor-induced changes to muscarinic cholinergic receptors are reversible. Nerve growth factor administration did not affect muscarinic cholinergic receptor density in striatal membranes and did not alter the relative content of cortical messenger RNAs encoding m1 and m3 muscarinic cholinergic receptor subtypes at postnatal day 14, as determined by reverse transcriptase-polymerase chain reaction. The up- and down-regulation of muscarinic cholinergic receptors induced by nerve growth factor during postnatal development may be temporally related events associated with concomitant changes in the activity of choline acetyltransferase.

Fos induction by nerve growth factor in the adult rat brain

The distribution of Fos, the protein product of the immediate early gene c-fos, was studied with immunocytochemistry in the adult male rat brain after nerve growth factor (NGF) administration. NGF was injected in the lateral cerebral ventricle through a previously implanted cannula. The total number of Fos-immunoreactive (ir) neurons in the brain was 2-3 times higher after NGF administration than in control animals (untreated or injected with cytochrome c). With respect to control rats, in the NGF-treated cases Fos-ir cells were more numerous in the anterior olfactory nucleus, in the medial prefrontal and anterior cingulate cortices, in the basal forebrain, in the preoptic and ventromedial nuclei of the hypothalamus, as well as anterior hypothalamic area, in the thalamic midline nuclei, and in some brainstem structures, such as the parabrachial nucleus. The relative quantitative increase of Fos-ir neurons varied in the different structures. In addition, Fos-ir neurons were evident after NGF administration in areas devoid of immunopositive cells in control animals. These included: frontoparietal and occipital cortical fields, the hypothalamic arcuate nucleus, and many brainstem structures, such as the dorsal nucleus of the lateral lemniscus, posterodorsal tegmental, medial and lateral vestibular, ventral cochlear, and prepositus hypoglossal nuclei. These findings demonstrate that the intracerebroventricular administration of NGF can induce c-fos expression in neurons in vivo. The distribution of Fos-ir neurons indicates that NGF can induce activation of functionally and chemically heterogeneous neuronal subsets in the brain.

Gangliosides and neurotrophic factors in neurodegenerative diseases: from experimental findings to clinical perspectives

A large body of experimental data suggests that neurotrophic molecules and/or substances that facilitate their action could be pharmaceutical agents for neurodegenerative pathologies. In particular, it has been demonstrated that nerve growth factor (NGF) exerts a physiological role for forebrain cholinergic neurons, while brain-derived neurotrophic factor (BDNF) seems to play a relevant role in rescuing dopaminergic neurons following damage. In addition, gangliosides are reported to potentiate neurotrophic factor effects in vitro as well as in vivo. In this study we examined the effects of the monosialoganglioside GM1 in different experimental models. The responsiveness of forebrain cholinergic neurons following NGF +/- GM1 was evaluated by assessing choline acetyltransferase (ChAT) activity in hippocampus, septal area and striatum of behaviorally impaired 24-month-old rats. NGF was intracerebroventricularly (i.c.v.) infused for 2 weeks while GM1 was given systemically for 3 weeks, starting from the beginning of NGF infusion. Moreover, the possible protective effects of GM1 were assessed following exposure of cultured cerebellar granule cells and dopaminergic mesencephalic neurons to different doses of 6-OH-DOPA, a metabolite of the dopamine pathway which has excitotoxic properties and has been hypothesized to participate in the pathology of Parkinson's disease. GM1 treatment to aged rats was seen to potentiate the NGF-induced increase of ChAT activity in the striatum ipsilateral to the NGF infusion. Moreover, in the striatum contralateral to the NGF infusion, GM1 increased ChAT activity above the control values, whereas NGF treatment alone did not affect enzymatic activity. GM1 treatment of cerebellar granule cells and mesencephalic neurons counteracted the dose- and time-dependent neurotoxicity of 6-OH-DOPA. These data support the notion that GM1 might prove useful in treating those pathological conditions where trophic factor deficits and/or excitotoxin-related toxicity play an important role.

In vivo activated brain astrocytes may produce and secrete nerve growth factor-like molecules

The cellular localization of the nerve growth factor-like immunoreactivity (NGF-LIR) has been studied in the septum and hippocampus of the rat brain 7 days following partial electrolytic lesion (2 mA, 30 s) of the septohippocampal pathways or after single intraventricular administration of 15 U of interleukin-1 beta (IL-1 beta). A double immunostaining technique which allowed a simultaneous localization of NGF-LIR and that of astroglia marker glial fibrillary acidic protein was used. Our data show that after both treatments, apart from neuronal localization of NGF-LIR typical for normal brain, many astrocytes both in the septum and hippocampus became NGF-like immunoreactive. Besides, NGF-LIR often formed a "halo" reaction around astrocytes. These results support the notion that activated in vivo brain astrocytes may, just as astrocytes growing in vitro, synthesize and secrete NGF-like molecules. Our findings may be of importance in considerations concerning trophic support to the cholinergic neurons of the basal forebrain nuclei whose impaired function is essentially responsible for some cognitive deficits in neurodegenerative diseases such as Alzheimer disease.

Nerve growth factor modulates the expression of muscarinic cholinergic receptor messenger RNA in telencephalic neuronal cultures from newborn rat brain

The effect of nerve growth factor (NGF) on muscarinic receptor subtypes was investigated in a primary culture of telencephalic neurons prepared from neonatal rats. The treatment with 100 ng/ml of NGF significantly enhanced choline acetyltransferase (ChAT) activity and intracellular acetylcholine (ACh) content during cultivation. The same treatment induced an early transient increase of the number of muscarinic cholinergic receptors (mAChR), as measured by [3H]quinuclidinyl benzilate binding to cell homogenate, that was followed by a dramatic decrease of the receptor density from the 9th day of culture. Atropine completely prevented the decrease of the maximal number of muscarinic recognition sites induced by NGF. Prolonged exposure of telencephalic neurons to NGF also induced a significant reduction of the relative content of the messenger RNA (mRNA) encoding m1 and m3 receptors, while the m4 transcript was increased by the treatment. We suggest that the prolonged stimulation of cholinergic neurons by NGF induces a downregulation of m1 and m3 mAChR and their mRNAs on the postsynaptic site, while it increases the synthesis of the functionally distinct m4 receptor subtype, which might be presynaptically localized on cholinergic neurons. The transient increase of the receptor number that occurs at the first days of culture was not paralleled by changes in the relative content of mAChR mRNAs and might be associated with the trophic activity of NGF on cholinergic synapses during early development.

Depressed nocturnal plasma melatonin levels in drug-free paranoid schizophrenics

The 24-h profiles of plasma melatonin and cortisol were evaluated in 7 drug-free male paranoid schizophrenics and in 7 healthy subjects matched to the patients for age, sex, body weight, height and season of testing. Blood samples were obtained at 20.00, 22.00, 24.00, 01.00, 02.00, 06.00, 08.00 and 12.00 h. Light was turned off from 21.00 to 07.00 h. Compared with that of the normal controls, the circadian rhythm of plasma melatonin was absent in paranoid schizophrenics (F7.84 = 7.30, p less than 0.0001; two-way ANOVA with repeated measures) whereas the 24-h profile of plasma cortisol was preserved, although at a slightly higher level (F1.12 = 26.810, p less than 0.0002). The melatonin/cortisol ratio was significantly higher in healthy subjects than in the schizophrenic patients. A functional relationship between disturbances in the melatonin rhythm especially and schizophrenia may be proposed, although the significance of this relationship remains to be elucidated.

Nerve growth factor differentially modulates the expression of its receptor within the CNS

The effect of nerve growth factor on the expression of nerve growth factor receptor in the central nervous system of newborn and adult rats was studied by means of immunohistochemistry with the monoclonal antibody 192-IgG. Both during development and in adulthood, the intracerebroventricular administration of nerve growth factor elicited a pronounced increase of nerve growth factor receptor-like immunoreactivity in the cell bodies and neural processes of the basal forebrain cholinergic nuclei, as compared to cytochrome c-treated rats (controls). A pronounced nerve growth factor-induced increase of nerve growth factor receptor-like immunoreactivity was also observed in central regions innervated by trigeminal and spinal ganglia. A moderate to a marked increase of nerve growth factor receptor-like immunoreactivity was evident in some mesencephalic visual system-related structures and thalamic nuclei expressing nerve growth factor receptor. In contrast, NGF treatment did not induce appreciable modification of nerve growth factor receptor-like immunoreactivity in cerebellar, brainstem, and spinal motor structures of newborn rats. In adult nerve growth factor-treated rats, a decrease of nerve growth factor receptor-like immunoreactivity was detected in the cerebellum, whereas no re-expression of nerve growth factor receptor-like immunoreactivity occurred in the motor structures that had expressed it in the first postnatal week. Finally, nerve growth factor was also found to enhance, in both adult and newborn rats, nerve growth factor receptor-like immunoreactivity associated with ependymal and subependymal cellular elements of the lateral and third ventricles, as well as with the leptomeninges overlying the superior colliculus and supraoptic area. The present results indicate that endogenous nerve growth factor or nerve growth factor-like molecules may play a dynamic role in a variety of cell populations of both the developing and mature mammalian central nervous system. We thus propose the nerve growth factor ability to modulate its receptor in vivo as a novel criterion to define nerve growth factor or nerve growth factor-like molecules, sensitive neuronal, and non-neuronal cells. Whereas this criterion does not intrinsically possess absolute physiological validity, its pharmacological concomitants might be relevant in view of the proposed therapeutical use of this trophic factor.

Failure of single electroconvulsive shock to affect daytime melatonin production in rats

It has been reported that, in the rat, different types of stressful procedures increase daytime melatonin production. Electroconvulsive shock (ECS) has been shown not to affect daytime pineal melatonin in rats killed 9 hr after its administration. It is possible that the long-lasting interval between the ECS administration and the sacrifice of the animals obscured an effect of the stressful procedure. In the present study, the effects of acute ECS on daytime melatonin production were evaluated in both ECS- and sham-treated rats killed 30, 60, 120, and 240 min after treatment. As compared with the sham-treated animals, rats receiving acute ECS (80 mA, 0.5 sec) did not show any significant difference in either pineal or serum melatonin levels at any time point after treatment. These data indicate that single ECS does not affect daytime melatonin production in the rat and suggest that the pineal gland may respond differently to the various stressful procedures.

Choline acetyltransferase messenger RNA expression in developing and adult rat brain: regulation by nerve growth factor

The polymerase chain reaction (PCR) was used to develop a method for detection and relative quantification of the choline acetyltransferase (ChAT) mRNA in neonatal and adult rat CNS. Oligonucleotide primers derived from a porcine ChAT cDNA sequence were used in coupled reverse transcriptase (RT)-PCR to amplify a cDNA sequence of 206 bp which arises in a cycle- and RNA-dependent manner and which hybridizes with both an internal oligonucleotide and a ChAT cDNA probe. ChAT mRNA was detected in spinal cord, septal area, striatum, cortex and hippocampus but not in cerebellum and cardiac or skeletal muscle. In the septal area, relative quantitative evaluation of ChAT mRNA levels by RT-PCR indicates that this transcript is developmentally regulated and increased following intracerebral administration of nerve growth factor (NGF) to both neonatal and young adult rats. This suggests that the increases of ChAT activity observed in basal forebrain during development or after NGF administration are, at least in part, associated with an increase in corresponding levels of mRNA.

Physical exercise at night blunts the nocturnal increase of plasma melatonin levels in healthy humans

The effects of physical exercise on nighttime melatonin secretion have never been investigated in humans. For this purpose, plasma melatonin levels were measured at different times during the day and the night in seven healthy men (aged 26-33 yrs), both in resting condition and before and after a physical exercise performed between 10.40 and 11.00 p.m.. The exercise consisted in bicycling on a bicycle ergometer at 50% of the personal maximal work capacity (MWC) for 10 min, followed by other 10 min of bicycling at 80% of the MWC. The results clearly showed that physical stress at night significantly blunts the nocturnal increase in plasma melatonin levels (group X time interaction: p less than 0.00001; two-way ANOVA with repeated measures). These findings, taken together with the data of the literature, suggest that the response of the pineal gland to provocative stimuli may depend on its level of activity when the stimulus is applied.

NGF Amplifies Expression of NGF Receptor Messenger RNA in Forebrain Cholinergic Neurons of Rats

In order to study the ligand-mediated regulation of NGF receptors in vivo, we assessed NGF receptor mRNA in the septal area of both neonatal and adult rats following intraventricular NGF administration. In neonatal rats NGF treatment, in comparison with cytochrome c, elicited a pronounced augmentation in the level of NGF receptor mRNA. A similar effect was also observed following continuous intraventricular NGF infusion in young adult rats. In addition, in this latter case, the increase in NGF receptor mRNA was associated with an increase in NGF receptor-related immunoreactivity, most likely associated with the cholinergic neurons, in the septal area. These results show that NGF itself may regulate expression of NGF receptor mRNA and corresponding protein levels in forebrain cholinergic neurons and suggest that NGF effects in the CNS may be mediated by an up-regulation of NGF receptors.

Nerve growth factor affects uninjured, adult rat septohippocampal cholinergic neurons

The effect of nerve growth factor on the intact versus injured septohippocampal cholinergic system of adult rats was studied. Nerve growth factor was continuously infused into the lateral ventricle of adult uninjured rats or rats that had received unilateral partial transection of the fimbria. Controls (operated and unoperated) received intraventricular infusion of cytochrome c. After 2 weeks of nerve growth factor or cytochrome c treatments, choline acetyltransferase and acetylcholinesterase activities were measured in the septal area and in the hippocampus (divided into dorsal, medial and ventral parts). The continuous infusion of nerve growth factor resulted in a marked dose-dependent increase of choline acetyltransferase activity in both septum and hippocampus of adult unlesioned rats. In lesioned rats the nerve growth factor treatment was capable of inducing choline acetyltransferase activity in the hippocampus of not only the lesioned but also the unlesioned side, as well as in the septal area. In addition, nerve growth factor affected choline acetyltransferase activity differently in the hippocampus of the operated side with respect to the contralateral side or in unoperated animals. The chronic infusion of nerve growth factor did not affect acetylcholinesterase activity in the septum or in the hippocampus of either lesioned or unlesioned rats. The present findings indicate that nerve growth factor is capable of modulating the function of not only damaged but also normal adult forebrain cholinergic neurons. This suggests that nerve growth factor may modulate the function of these neurons in adulthood.

GM1 ganglioside potentiates the effect of nerve growth factor in preventing vinblastine-induced sympathectomy in newborn rats

The effects of vinblastine (VNB) and nerve growth factor (NGF) administrations were assessed on sympathetic nerve terminals by measuring the noradrenaline (NA) content in the heart, spleen and kidneys of developing animals. Six-day-old rats, treated with 0.15 mg/kg VNB on postnatal day 3 (P3) showed a dramatic decrease of NA content in all these organs. This reduction was prevented by daily administrations of NGF on P3, P4 and P5. The effectiveness of NGF in inhibiting the VNB-induced sympathectomy was related to the dose administered and to the time interval between the VNB administration and the first NGF injection given on P3. Dose-response curves to NGF (ranging from 0.01 to 0.5 mg/kg) were obtained in both heart and spleen of VNB-treated animals. Thus, this experimental paradigm provides a quantitative assessment of the NGF activity in vivo. The systemic administration of GM1 (30 mg/kg) on P3, P4 and P5, was able to potentiate the NGF activity in preventing the VNB-induced sympathectomy. This GM1 effect was more evident in the heart and may be, at least in part, attributed to increased NGF prevention of neuronal cell death due to VNB. These results suggest an in vivo interaction between exogenous GM1 and NGF and are consistent with the view that neuronal cell repair related to in vivo administration of this ganglioside may rely on its capability to modulate the activity of endogenously occurring neuronotrophic factors.

General toxicity and peripheral nerve alterations induced by chronic vincristine treatment in the rabbit

The effects of five 0.3 mg/kg intravenous administrations of vincristine (VCR) at weekly intervals were studied in the rabbit. Body weight gain was impaired starting from the first injection, while gross signs of motor paralysis and hair loss initiated from the third week. At the end of the observation period blood analysis revealed normocytic normochromic anemia, elevated serum creatine kinase, and low serum alkaline phosphatase, whereas all the tested parameters related to liver and kidney functions where within normal limits. The decreased number of red blood cells was the consequence of a complete, although reversible, blockade of staminal hematopoietic activity. Two important indexes of peripheral nerve function were clearly altered at the end of the treatment: (i) the sciatic nerve conduction velocity in vitro was 27% reduced and (ii) the latency between sciatic nerve stimulation and extensor digitorum longus (EDL) twitch in vivo was 34% prolonged. The usefulness of the rabbit as an animal model to study side-effects of VCR treatment is discussed.

GM1 ganglioside counteracts selective neurotoxin-induced lesion of developing serotonin neurons in rat spinal cord

The effect of exogenous monosialoganglioside GM1 on neurotoxin-induced lesioning of bulbo-spinal serotonergic neurons of newborn rats was studied by means of biochemical and immunocytochemical techniques. 5,7-dihydroxytryptamine (5,7-HT, a selective serotonin neurotoxin) treatment of newborn rats caused a pronounced reduction of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in the thoracic and lumbar spinal cord, while an increase of 5-HT and 5-HIAA was found in the pons medulla. These biochemical alterations were regionally correlated with similar changes in 5-HT nerve terminal density analyzed by image analysis. GM1 administration (30 mg/kg for 4 consecutive days) antagonized the reduction of 5-HT and 5-HIAA levels induced by 5,7-HT treatment in the lumbar spinal cord of 2-month-old rats, as well as the decrease of 5-HT nerve terminal density in both thoracic and lumbar spinal cord of 1- and 2-month-old rats. A minor counteracting effect of GM1 was found in the pons medulla where the neurotoxin induced an increase of 5-HT and 5-HIAA levels. These data support the hypothesis that GM1 may have a preventing action on retrograde degenerative processes following chemical lesion and/or a growth-stimulating effect on injured 5-HT neurons.

Left ventricular mass and function before and after antihypertensive treatment

We have studied the effect of blood pressure control upon left ventricular mass and function. Twenty hypertensive patients without clinical or electrocardiographic signs of cardiac involvement were given sequentially: placebo for two weeks; captopril (250 mg/day) for eight weeks; and captopril (125 mg/day), alone or combined with chlorthalidone (25 mg/day), for eight weeks. M-mode echocardiography was performed at the end of placebo period, after eight and after 16 weeks active treatment. Blood pressure was significantly reduced (p less than 0.01) by therapy, the maximum decrease being observed at the end of the study. Similarly, interventricular septal thickness, posterior wall thickness and left ventricular mass index showed a significant reduction (P less than 0.01 at the eighth and P less than 0.001 at the 16th week), while no changes were detected in left ventricular function. Furthermore, both wall stress index at end-diastole and end-systolic stress were significantly lowered by treatment (at the 16th week P less than 0.01 and P less than 0.001, respectively). Baseline systolic blood pressure was inversely correlated with the ratio of the left ventricular radius to posterior wall thickness (r = -0.97, P less than 0.001) but no relation was found between post-treatment fall in either systolic or diastolic blood pressure and left ventricular mass index. After treatment more patients showed normal left ventricular wall thickness in relation to systolic blood pressure. We conclude that in uncomplicated hypertensive patients captopril, either alone or combined with chlorthalidone, can reverse left ventricular hypertrophy by decreasing both septal and posterior wall thickness.(ABSTRACT TRUNCATED AT 250 WORDS)