Prevalence of urogenital, anal, and pharyngeal infections with Chlamydia trachomatis, Neisseria gonorrhoeae, and Mycoplasma genitalium: a cross-sectional study in Reunion island.

BACKGROUND: Recommendations for sexually transmitted infection (STI) screening vary significantly across countries. This study evaluated the prevalence of urogenital and extragenital infections with Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma genitalium (MG) in patients visiting a French STI clinic in the Indian Ocean region to determine whether current STI screening practices should be updated. METHODS: This cross-sectional study examined all patients who visited the STI clinic between 2014 and 2015. Triplex polymerase chain reaction screening for CT, NG, and MG was performed on urine, vaginal, pharyngeal, and anal specimens (FTD Urethritis Basic Kit, Fast Track Diagnostics, Luxembourg). RESULTS: Of the 851 patients enrolled in the study, 367 were women (367/851, 43.2%) and 484 were men (484/851, 56.0%). Overall, 826 urogenital specimens (826/851, 97.1%), 606 pharyngeal specimens (606/851, 71.2%), and 127 anal specimens (127/851, 14.9%) were taken from enrolled patients. The prevalence of urogenital CT and MG was high in women ≤25 years (19/186, 10.21%; 5/186, 2.69%) and in men who have sex with women ≤30 years (16/212, 7.54%; 5/212, 2.36%). Among patients with urogenital CT infection, 13.7% (7/51) had urethritis. All patients with urogenital MG infection were asymptomatic. Men who have sex with men had a high prevalence of pharyngeal CT (2/45, 4.44%) and NG (3/44, 6.81%) and a high prevalence of anal CT (2/27, 7.41%), NG (2/27, 7.40%), and MG (1/27, 3.70%). After excluding patients with concomitant urogenital infection, extragenital infections with at least 1 of the 3 pathogens were found in 20 swabs (20/91, 21.9%) taken from 16 patients (16/81, 19.7%), all of them asymptomatic. CONCLUSIONS: Routine multisite screening for CT, NG, and MG should be performed to mitigate the transmission of STIs in high-risk sexually active populations.

[Endocrine neurons and neurotransmission: 40 years of cytochemical studies]. / Neurones endocrines et neurotransmission : 40 ans de recherches cytochimiques.

Conceptual advances about chemical neurotransmission during the last 40 years have benefited a lot from histocytochemical approaches and from a particular experimental model, the endocrine hypothalamic neurons. New concepts like cotransmission, neuronal versatility, somatodendritic release of neurotransmitters, volume transmission, differential routing or cooperative synthesis of mediators, have often been issued from this set of methodologies and from their application to neurosecretory neurons. This review, mainly based on the results of our group, is aiming at illustrating how the peculiar metabolism of these neurons and their location at the neuro-endocrine interface have allowed discovering new aspects of neurotransmission, first considered as exceptions but then generalized to the whole nervous system. These new concepts shed lights on the normal functioning of the brain and definitely contribute to diversify pharmacological approaches of pathological neurotransmission.

[Migration and differentiation of neurons producing gonadotropin-releasing hormone under conditions of serotonin excess in the brain of mouse embryos].

The work has been carried out on mice of the Tg8 line with knockout of gene of monoamineoxidase A with an increase of serotonin and noradrenaline content in the brain, and on mice of the C3H line with unchanged genome and normal concentration of monoamines. An immunocytochemical study has been performed of development of neurons producing gonadotropin-releasing hormone (GnRH) under conditions of excess of serotonin and noradrenaline in the mice in embryogenesis. The GnRH-neurons were revealed at the 18th day of embryonic development in telencephalon along trajectory of their migration from olfactory bulbs to the retrochiasmatic area. In telencephalon of mouse embryos of the Tg8 line, a redistribution of the GnRH-neurons along their migration trajectory was observed as compared with embryos of the C3H line mice. The percent of the GnRH-neurons in the Tg8 mouse embryos in caudal parts of the migration trajectory was lower than in rostral parts, the opposite distribution of the neurons being observed in the C3H line mouse embryos; at the excess of serotonin and noradrenaline in the Tg8 line mouse embryos, the total amount of GnRH-neurons in the brain was lower than in the C3H mice. In males of the Tg8 line mice under conditions of excess of serotonin and noradrenaline the optical density of neurons, which correlated with the GnRH concentration in the cell, was higher than in control mice. Thus, in the Tg8 mice under conditions of the serotonin and noradrenaline excess, migration of the GnRH-neurons to their final anlage in hypothalamus is accelerated as well as the total number of the GnRH-neurons decreases, which indicates a decrease of proliferation of cells-precursors and the earlier differentiation of neurons.

The unexpected role of bioaerosols in the Oxidative Potential of PM.

Bioaerosols represent up to 15-25% of PM by mass, but there is currently no assessment of their impact on Oxidative Potential (OP), or capacity of particulate matter (PM) to produce damaging oxidative reactions in the human lungs. Here, the OP of selected bioaerosols (bacteria cells vs fungal spores) was assessed through the cell-free DTT assay. Results show that bioaerosols induce Reactive Oxygen Species (ROS) production, varying along the microorganism type, species, and concentration. Fungal spores show up to 10 times more ROS generation than bacterial cells. At the highest concentrations, fungal spores present as much oxidative reactivity as the most redox-active airborne chemicals (Copper, Naphtoquinone). Moreover, bioaerosols substantially influence OP of ambient PM and that of its chemical constituents: in presence of A. fumigatus spores, the OP of Cu/NQ is increased by a factor of 2 to 5, whereas, 104 and 105 S. epidermidis bacterial cells.mL-1 halves the OP of Cu/NQ. Finally, viable and gamma-rays-killed model bioaerosols present similar oxidative reactivity, suggesting a metabolism-independent cellular mechanism. These results reveal the importance of bioaerosols for PM reactivity. PM toxicity can be modified due to bioaerosols contribution or by their ability to modulate the OP of toxic chemicals present in PM.

Degeneration of dopaminergic neurons triggers an expression of individual enzymes of dopamine synthesis in non-dopaminergic neurons of the arcuate nucleus in adult rats.

Non-dopaminergic neurons expressing individual complementary enzymes dopamine (DA) synthesis were shown to produce DA in cooperation [Ugrumov, M., Melnikova, V., Ershov, P., Balan, I., Calas A., 2002. Tyrosine hydroxylase- and/or aromatic L-amino acid decarboxylase-expressing neurons in the rat arcuate nucleus: ontogenesis and functional significance. Psychoneuroendocrinology 27, 533-548; Ugrumov, M.V., Melnikova, V.I., Lavrentyeva, A.V., Kudrin, V.S., Rayevsky, K.S., 2004. Dopamine synthesis by non-dopaminergic neurons expressing individual complementary enzymes of the dopamine synthetic pathway in the arcuate nucleus of fetal rats. Neuroscience 124, 629-635]. This study was aimed at testing our hypothesis that the cooperative synthesis of DA in non-dopaminergic neurons is an adaptive reaction under functional insufficiency of the dopaminergic system. Functional insufficiency of the tuberoinfundibular dopaminergic system was provoked by 6-OHDA-induced degeneration of dopaminergic neurons in the arcuate nucleus in adult rats. Bienzymatic (dopaminergic) neurons and monoenzymatic neurons expressing tyrosine hydroxylase (TH) or aromatic L-amino acid decarboxylase (AADC) were detected with a double-immunofluorescent technique on cryostat sections. The 6-OHDA-induced degeneration of dopaminergic neurons was accompanied by a significant increase of the number of monoenzymatic TH neurons and AADC neurons that appears to support our hypothesis. The reaction of bienzymatic and monoenzymatic neuron populations to the 6-OHDA administration occurred to be region-specific. The former disappeared in the dorsomedial region of the arcuate nucleus while the latter increased in the ventrolateral region. Thus, degeneration of dopaminergic neurons in the arcuate nucleus of adult rats is accompanied by the expression of individual enzymes of DA synthesis in non-dopaminergic neurons that may be an adaptive reaction.

Long-lasting effects of serotonin deficiency on differentiating peptidergic neurons in the rat suprachiasmatic nucleus.

Serotonin (5-HT, 5-hydroxytryptamine) is known to be an inductor of the brain development [Whitaker-Azmitia, P.M., Druse, M., Walker, P., Lauder, J.M., 1996. Serotonin as a developmental signal. Behav. Brain Res. 73, 19-29; Ugrumov, M.V., 1997. Hypothalamic monoaminergic systems in ontogenesis: development and functional significance. Int. J. Dev. Biol. 41, 809-816]. This study was aimed to test whether it provides long-lasting effects on the differentiating vasoactive intestinal polypeptide (VIP) and vasopressin (VP) neurons of the suprachiasmatic nucleus (SCN) in rats. To this aim, 5-HT was depleted in fetal brain by daily injections of p-chlorophenylalanine (pCPA), an inhibitor of 5-HT synthesis, to pregnant rats from the 13th to the 21st day of gestation. Pregnant rats injected with saline served as controls. The offsprings (males) of pCPA-treated and control pregnant rats were maintained after birth for two months under normal laboratory conditions. Then, the SCN was processed for immunocytochemistry of VIP and VP and in situ hybridization of appropriate mRNAs. There were no differences in concentrations of VIP and VP mRNAs in the SCN in adult offsprings of the 5-HT-depleted pregnant rats compared to the controls. Moreover, 5-HT deficiency did not induce any change in size of VIP-immunoreactive (IR) and VP-IR neurons. Conversely, both the numbers of VIP- and VP-immunoreactive neurons and concentrations of the peptides in cell bodies increased significantly. It is concluded that 5-HT provides long-lasting effects on differentiating VIP and VP neurons in the SCN resulting in attenuated release rather than elevated synthesis of both peptides in adulthood.

Projections from the hypothalamus to the posterior lobe in rats during ontogenesis: 1,1'-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate tracing study.

The objective of this study was to determine the schedule of the arrival of the axons from the hypothalamus to the posterior lobe of the pituitary (PL) in rats during ontogenesis by using the fluorescent lipophilic carbocyanine dye 1,1'-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate (DiI) as a retrograde tracer. After preliminary fixation of the brain, DiI crystals were implanted in the PL on embryonic day 15 (E15), E16, E17, and E19 as well as on postnatal day 2 (P2) and P9. This was followed by a DiI retrograde diffusion along the plasma membrane and subsequent staining of hypothalamic neuronal cell bodies. The supraoptic nucleus (SO) contained an accumulation of fluorescent cells that extended toward the diamond-like swelling of the third ventricle as early as E15. These data suggest that the magnocellular neurons of the SO send their axons to the PL at the very beginning of differentiation, perhaps even before reaching their final position. The initial axons of the neurons of the paraventricular nucleus proper (PV) appeared to reach the PL significantly later, at E17. In addition to the SO and the PV, accessory magnocellular nuclei contributed to the innervation of the PL in perinatal rats. The neurons of the retrochiasmatic accessory nucleus first sent their axons to the PL on E16-E17. Axons that originated from other accessory hypothalamic nuclei reached the PL after birth, suggesting a delay in their involvement in the regulation of visceral functions compared with other magnocellular nuclei. Thus, the axons of magnocellular neurons reach the PL unexpectedly early in embryogenesis, raising the possibility of the functional significance of vasopressin and oxytocin as fetal neurohormones.

Hypothalamic galanin-immunoreactive neurons projecting to the posterior lobe of the rat pituitary: a combined retrograde tracing and immunohistochemical study.

UNLABELLED: To identify the galanin-immunoreactive neurons projecting to the posterior lobe of the pituitary in the rat hypothalamus, a retrograde tracer (complex of wheat germ agglutinin-enzymatically inactive horseradish peroxidase-colloidal gold) was injected into the posterior lobe of the pituitary. Sections of the hypothalamus were treated with a combination of silver enhancement of retrogradely transported tracer and immunohistochemistry of galanin. Of the total number of hypothalamic cells doubly labeled with retrograde tracing and galanin-immunostaining, 56-60% were found in the supraoptic nucleus, 18-23% in the retrochiasmatic nucleus, 8-10% in the lateral magnocellular portion of the paraventricular nucleus. The ratio of (number of doubly labeled cells/number of galanin-immunoreactive cells) in each of the above regions was similar to the ratio of (number of retrogradely labeled cells/number of Nissl-stained cells) in the supraoptic nucleus. Of all retrogradely labeled cells in the hypothalamus, 51-56% also contained galaninlike immunoreactivity. IN CONCLUSION: (1) galanin-immunoreactive fibers in the posterior lobe of the pituitary originate mainly in the supraoptic nucleus, retrochiasmatic nucleus, and lateral magnocellular portion of the paraventricular nucleus, (2) most of galanin-immunoreactive cells in these regions project to the posterior lobe of the pituitary, and (3) about half the neurons constituting the hypothalamo-neurohypophyseal system contain galaninlike immunoreactivity.

Development of intracerebral dopaminergic grafts: a combined immunohistochemical and autoradiographic study of its time course and environmental influences.

The aim of the study was to obtain a description of some aspects of the development of intracerebral dopaminergic grafts, namely, the time course of the glial reaction and its relation to cell division on one hand, and the development of graft-originated innervation and its dependence on adequate matching of the implanted neurons and target site on the other hand. Cell suspensions obtained from the mesencephalon or hypothalamus of embryonic day (ED) 14 rat embryos were implanted into the striatum or lateral hypothalamus of adult rats following the destruction of the nigrostriatal system of the hosts. Animals were sacrificed at different postimplantation times, and the development of the graft was followed by immunohistochemistry by using antisera directed against tyrosine hydroxylase (TH) or glial fibrillary acidic protein (GFA). Furthermore, the existence of cell division at various times following implantation was examined by performing autoradiography on immunostained sections after prior intraventricular administration of 3H-thymidine to the host. The first stage of the development of intracerebral grafts was characterized by the existence of intense cell division within the grafted tissue, lasting about 2 weeks, and also in the host tissue surrounding the graft, lasting only about 6 days. The cell division in the host tissue was paralleled by the existence of a strong glial reaction which, however, did not extend into the graft itself. Glial reaction in the host tissue gradually decreased at later times and disappeared by 4 weeks postimplantation without leaving behind a noticeable glial scar. The graft itself was, however, transiently filled with a population of reactive astroglial cells between 3 and 6 weeks postimplantation. Within grafts of mesencephalic tissue located in the striatum TH-positive neurons were distributed evenly at short times postimplantation (2-6 days). At later time a compartmentation could be observed, with TH-positive neurons being aligned along the graft-host interface or clustered within the graft itself. Innervation of the host tissue by TH-positive fibers increased between 1 and 6 weeks postimplantation. On the other hand, no compartmentation and reinnervation of surrounding host tissue was observed for intrahypothalamic grafts of mesencephalic tissue or intrastriatal grafts of hypothalamic tissue. This last observation indicates that adequate matching of implanted neurons and target tissue plays an important role in the development of intracerebral dopaminergic grafts.

Organization of tyrosine-hydroxylase immunopositive neurons in the brain of the crested newt, Triturus cristatus carnifex.

The localization of neurons, fibers, and terminals containing tyrosine hydroxylase (TH)-like immunoreactivity was studied in the brain of the crested newt by using an antiserum to rat phaeochromocytoma tyrosine hydroxylase. Immunoreactive cells and fibers were found in the spinal cord, the medulla oblongata (lateral periventricular areas), and the acousticolateral area. In the tegmentum mesencephali, two bilateral clusters of labelled cells were localized in the ventrolateral periventricular gray extending toward the caudal hypothalamus. In the hypothalamic tuberal lobes, the TH-like reactive neurons, frequently of CSF-contacting type, lined the dorsal wall of the lateral infundibular recesses. A thick network of TH-like reactive nerve fibers and terminals was observed in the perivascular zone of the median eminence and in the adenohypophysial pars intermedia. A number of labelled cell bodies were also found in the dorsal thalamus (pars intercalaris diencephali), the paraventricular organ, and the ventral wall of the preoptic recess. In the telencephalon, immunoreactive innervation was identified in the striatum, together with immunopositive cell bodies in the olfactory bulbs. The pattern of organization of TH-immunoreactive systems in the newt showed, except for some peculiarities (e.g., the labelled cell bodies in dorsal thalamus), close similarities to the arrangement typical of mammals.

Tyrosine hydroxylase-expressing and/or aromatic L-amino acid decarboxylase-expressing neurons in the mediobasal hypothalamus of perinatal rats: differentiation and sexual dimorphism.

In this quantitative and semiquantitative immunocytochemical study, the authors evaluated the differentiation of neurons expressing tyrosine hydroxylase (TH) and/or aromatic L-amino acid decarboxylase (AADC) in the mediobasal hypothalamus (MBH) of male and female rats on embryonic day 18 (E18), E20, and postnatal day 9 (P9). Four neuronal populations were distinguished according to either enzyme expression or neuron location. The earliest and most prominent first population was represented by TH-immunoreactive (IR)/AADC-immunonegative (IN) neurons that were detected initially at E18 and always were located in the ventrolateral region of the MBH. The second population of TH-IN/AADC-IR neurons was observed first at E20 and, after that time, was distributed dorsomedially. The third minor population of TH-IR/AADC-IR neurons initially was detected at E20 and was located dorsomedially. The fourth population was represented by TH-IR/AADC-IN neurons that were distributed in the dorsomedial region at any studied age. The numbers of TH-IR and AADC-IR neurons increased from their initial detection at E18 and E20 until P9. The area of TH-IR and AADC-IR neurons also increased from E18 to E20 and from E20 to P9, respectively. Both TH-IR and AADC-IR neurons showed sex differences in the neuron number, size, and optic density (OD). The numbers of TH-IR neurons in males exceeded those of females at E20 and at P9, although, at P9, sexual dimorphism was a characteristic only of the ventrolateral population. The area and OD of TH-IR neurons from females exceeded those from males in the entire mediobasal hypothalamus (MBH) at E18 and E20 but only in its dorsomedial region at P9. Sexual dimorphism also was an attribute of AADC-IR neurons at E20 and P9. Their number, size, and OD were significantly higher in females than in males. Thus, the MBH of perinatal rats contained two major populations of TH-IR/AADC-IN or TH-IN-AADC-IR neurons and a minor population of TH-IR/AADC-IR neurons. The differentiating neurons expressing either enzyme showed sexual dimorphism.

Immunolocalization of aromatic L-amino acid decarboxylase in goldfish (Carassius auratus) brain.

The distribution of monoamines (catecholamines and serotonin) in fishes has been previously studied by immunohistochemistry of both the monoamines themselves and their biosynthetic enzymes. But the distribution of neurons containing aromatic L-amino acid decarboxylase, an enzyme involved in the biosynthesis of both catecholamines and serotonin, has up to now not been investigated. In order to improve knowledge about the localization of aromatic L-amino acid decarboxylase, neurons containing this enzyme were mapped immunohistochemically in the goldfish brain. Furthermore, neurons bearing aromatic L-amino acid decarboxylase immunoreactivity have been compared with those containing tyrosine hydroxylase and serotonin immunoreactivities. Our results show that distribution of aromatic L-amino acid decarboxylase immunoreactivity generally coincides with that of tyrosine hydroxylase and serotonin. Nevertheless, the presence of nine D cell groups (containing aromatic L-amino acid decarboxylase but lacking both catecholamines and serotonin) and six groups of neurons which are aromatic L-amino acid decarboxylase-immunonegative but contain tyrosine hydroxylase, and might produce L-DOPA, have been revealed. The occurrence of both D cell groups and presumptive L-DOPA neurons in goldfish brain is discussed in relation to similar findings in fish and mammalian brain.

Ectopic expression of non-catecholaminergic tyrosine hydroxylase in rat hypothalamic magnocellular neurons.

Hypothalamic magnocellular neurons constitute a good model of neurochemical plasticity, because a single neuron can express various combinations of neuropeptides and enzymes under different physiological conditions. Tyrosine hydroxylase has been shown to occur ectopically in various non-catecholaminergic neurons. We investigated the expression of tyrosine hydroxylase and its possible role in the magnocellular neurons of the supraoptic and paraventricular nuclei in salt-loaded and lactating rats, using in situ hybridization and immunohistochemistry, alone or combined, in light and electron microscopy. Our results demonstrated that almost 25% of the magnocellular neurons in the supraoptic nucleus and 15% in the paraventricular nucleus expressed tyrosine hydroxylase in salt-loaded rats, and 10% in the supraoptic nucleus of two-day lactating rats. Double labelling showed that this tyrosine hydroxylase was essentially synthesized in magnocellular neurons expressing vasopressin. The ultrastructural localization of tyrosine hydroxylase was less homogeneous in the cytoplasm of magnocellular neurons than in periventricular neurons. In lactating and salt-loaded rats, magnocellular neurons were devoid of the catecholamine biosynthesis markers aromatic L-amino acid decarboxylase, L-3,4 dihydroxyphenylalanine, dopamine and GTP-cyclohydrolase I. Tyrosine hydroxylase expression did not increase after rats were injected with reserpine. Our results indicate that the phenotype of the magnocellular neurons expressing tyrosine hydroxylase in lactating and salt-loaded rats is non-catecholaminergic, and suggest that this tyrosine hydroxylase might be involved in osmoregulation.

Ultrastructural immunocytochemical study of the dopaminergic innervation of the rat lateral septum with anti-dopamine antibodies.

The dopaminergic innervation of the rat lateral septum has been investigated at ultrastructural level by immunocytochemistry using the unlabelled peroxidase-anti-peroxidase method with anti-dopamine antibodies. The specificity of the reaction has been carefully checked by immunological and histochemical controls. A strong immunoreaction was observed in fibres of the lateral septum as well as in their cells of origin in the ventral tegmental area. In the lateral septum, dopamine-immunoreactive fibres were localized in two distinct areas. A first area, located ventrally in the anterior part of the septum was characterized by a high density of immunoreactive varicosities with barely visible intervaricose segments. A more dorsal area, extending throughout the anteroposterior region of the septum, was characterized by immunoreactive fibres in pericellular arrangements. Electron microscopic observations revealed no difference in the ultrastructure of dopamine-immunoreactive profiles in the different areas. Reaction product was found in vesicles, linked to microtubules and in the cytoplasm. Three types of vesicles were seen: (i) small vesicles (30-50 nm) with varying intensity of immunoreaction, filling up the varicosities; (ii) rare large clear vesicles (50-80 nm) with no internal immunoreaction; (iii) very rare large dense vesicles (50-100 nm) with a strong dopamine immunoreactivity. Labelled profiles were observed in clearly defined asymmetrical synaptic contacts with somata and dendrites. Due to the lack of previous work dealing with the use of anti-dopamine antibodies for electron microscope immunocytochemistry, our observations are compared to previous data obtained by more indirect labelling techniques.

Serotonergic projections to the spinal cord but not those to the olfactory bulb also contain substance P. A combined immunocytochemical and autoradiographic study following retrograde axonal transport of [3H]serotonin labeled products.

Co-localization of substance P with serotonin in raphe projection neurons was studied by combining substance P immunocytochemistry and autoradiography following uptake and retrograde axonal transport of [3H]serotonin and/or its products from target areas. In this study, two central pathways in the rat were investigated: the serotonergic projections of the midbrain raphe to the olfactory bulb and those of the medullary raphe that innervate the thoracic spinal cord. Two hours after pargyline pretreatment, injections of 10(-4) M [3H]serotonin were made either into the olfactory bulb or into the spinal cord and respectively 24 or 60 h thereafter, rats were administered with colchicine. After a 24 h survival time, the paraformaldehyde fixed brains were investigated for substance P immunocytochemistry and then treated for light and electron microscopy autoradiography. Combining both methods, we can define on the same tissue sections at least three labeled neuronal populations: substance P immunolabeled neurons, radiolabeled neurons and doubly immuno-radiolabeled neurons. In the midbrain raphe cells as well as in the olfactory bulb nerve terminals, two kinds of labeled profiles were detected: substance P immunoreactive profiles and radiolabeled ones. The radiolabeled cell bodies of the midbrain raphe (403 counted cells) were never reactive to substance P antibodies. Moreover, they were distributed caudally to substance P stained perikarya. In contrast, in the medullary raphe, of the 336 radiolabeled cell bodies 162 were stained after substance P antibody treatment. They represent about 48% of the serotonin radiolabeled neurons projecting to the thoracic spinal cord, where a great number of varicosities were observed immunolabeled, radiolabeled and doubly immuno-radiolabeled in the dorsal horn. At the ultrastructural level, cell bodies and dendritic processes were also doubly labeled. Both labelings were observed over the cytoplasm and some organelles or perikarya. These observations provide a morphological basis to support the hypothesis that substance P can occur within some but not all serotonergic neurons and raise questions about the expression of this peptide in these systems as well as the modes of interaction of these transmitter molecules.

Anatomical distribution and ultrastructural organization of the GABAergic system in the rat spinal cord. An immunocytochemical study using anti-GABA antibodies.

gamma-Aminobutyric acid (GABA)-containing elements have been studied by light and electron microscopy in the rat spinal cord, using immunocytochemistry with anti-GABA antibodies. Light microscopy showed immunoreactive somata localized principally in laminae I-III, and occasionally in the deeper laminae of the dorsal horn and in the ventral horn. Small somata were also observed around the central canal. Punctate GABA-immunoreactive profiles were particularly concentrated in laminae I-III, and moderately abundant in the deeper laminae and in the ventral horn where they were observed surrounding the unlabelled motoneurons. At the ultrastructural level, the punctate profiles corresponded to GABA-containing axonal varicosities or small dendrites. GABA-immunoreactive varicosities were presynaptic to labelled or unlabelled dendrites and cell bodies. Some unlabelled terminals presynaptic to unlabelled dendrites received symmetrical synaptic contacts from GABA-immunoreactive terminals. These results confirm data obtained with L-glutamate decarboxylase immunocytochemistry, and support the role of GABA in pre- and postsynaptic inhibition in the spinal cord, respectively via axoaxonal and axosomatic or axodendritic synapses.

Long-lasting effect of catecholamine deficiency on differentiating vasopressin and oxytocin neurons in the rat supraoptic nucleus.

According to our earlier study, the catecholamine depletion in neonatal rats resulted in stimulation of the vasopressin and oxytocin gene expression in the neurons of the supraoptic nucleus. The present study extends this line, evaluating whether the catecholamine deficiency provides a long-lasting effect on the differentiating vasopressin and oxytocin neurons of the supraoptic nucleus. Catecholamines were depleted by daily injections of an inhibitor of the catecholamine synthesis, alpha-methyl-p-tyrosine, first, to pregnant rats from the 9th to the 21st day of gestation and, then, to their pups from the 2nd to the 10th postnatal day. The animals, injected with saline instead of drugs, served as controls. The pharmacologically-treated and control rats were kept for four months under normal laboratory conditions until processing the materials for semi-quantitative in situ hybridization and immunocytochemistry of vasopressin and oxytocin messenger RNAs and peptides, respectively. There were no differences in the vasopressin and oxytocin messenger RNA concentrations in the supraoptic nucleus in rats following preliminary catecholamine depletion compared to controls. Conversely, the catecholamine deficiency resulted in an increased content of the vasopressin-immunoreactive material in cell bodies and processes. This was also the case for the oxytocin-immunoreactive cell bodies but only in females, suggesting an interference of catecholamines with sexual steroids in their action. The number and size of vasopressin and oxytocin neurons did not change in pharmacologically-treated rats compared to the controls. Thus, the catecholamine deficiency in the course of the neuron differentiation resulted in a long-lasting augmentation of the intracellular content of vasopressin and oxytocin but did not influence the vasopressin and oxytocin gene expression. This might be explained rather by the reduced level of peptide release than by an increased level of the peptide production.

Oxytocinergic and serotonergic innervation of identified lumbosacral nuclei controlling penile erection in the male rat.

Penile erection is due to activation of proerectile neurons located in the sacral parasympathetic nucleus of the L6-S1 spinal cord in the rat. Contraction of the ischiocavernosus and bulbospongiosus striated muscles, controlled by motoneurons located in the ventral horn of the L5-L6 spinal cord, reinforces penile erection. Physiological and pharmacological arguments have been provided for a role of oxytocin and serotonin in the spinal regulation of penile erection. Immunohistochemistry of oxytocinergic and serotonergic fibres was performed at the lumbosacral level of the male rat spinal cord, and combined with retrograde tracing from the pelvic nerve or from the ischiocavernosus and bulbospongiosus muscles using wheat germ agglutinin-horseradish peroxidase. Sacral preganglionic neurons retrogradely labelled from the pelvic nerve formed a homogeneous population, predominant at the L6 level. Motoneurons retrogradely labelled from the ischiocavernosus and bulbospongiosus muscles were observed in the medial part of the dorsolateral and in the dorsomedial nuclei. Fibres immunoreactive for oxytocin were mainly distributed in the superficial layers of the dorsal horn, the dorsal gray commissure and the sacral parasympathetic nucleus. Some of these fibres were apposed to retrogradely-labelled sacral preganglionic neurons and at the ultrastructural level, some synapses were evidenced. Fibres immunoreactive for serotonin were largely and densely distributed in the dorsal horn, the dorsal gray commissure, the sacral parasympathetic nucleus and the ventral horn. Some serotonergic fibres occurred in close apposition with retrogradely-labelled sacral preganglionic neurons and motoneurons, and synapses were demonstrated at the ultrastructural level. This study provides morphological support for a role of oxytocin and serotonin on sacral preganglionic neurons innervating pelvic organs and motoneurons innervating the ischiocavernosus and bulbospongiosus muscles.

Ultrastructural immunocytochemistry of gamma-aminobutyrate in the cerebral and cerebellar cortex of the rat.

gamma-Aminobutyrate containing structures in the cerebral and cerebellar cortex of the rat were visualized by an immunocytochemical method using glutaraldehyde fixation and an antiserum developed against a gamma-aminobutyrate-glutaraldehyde-protein conjugate. Labelled elements (perikarya and cell processes) were observed to be distributed throughout the layers of the cerebral cortex in a pattern similar to that described using glutamate decarboxylase immunocytochemistry. The morphological features of many immunoreactive cell bodies were typical of stellate neurons. In the cerebellar cortex, Purkinje, basket, Golgi and stellate, cell bodies were found to be immunoreactive along with numerous labelled neuronal processes. At the ultrastructural level, the labelled processes in both areas corresponded to immunoreactive dendrites and fibres. Labelled synaptic boutons, generally of the symmetrical type, could also be seen in contact with positive or negative cell bodies and dendrites. In the cerebellum, glomeruli could be clearly identified including mossy fibres surrounded by unlabelled dendrites in contact with immunoreactive terminals. At the subcellular level in both brain regions, the areas occupied by the Golgi apparatus were never labelled, although the nuclei had varied reactions. The strong glutaraldehyde fixation that limits the diffusion of gamma-aminobutyrate limits also antibody diffusion. However, this fixation is compatible with a good morphological preservation and should enable immunocytochemistry studies to be compared to other methods such as autoradiography.

gamma-Aminobutyric acid and 5-hydroxytryptamine interrelationship in the rat nucleus raphe dorsalis: combination of radioautographic and immunocytochemical techniques at light and electron microscopy levels.

Serotonin and gamma-aminobutyric acid (GABA) neurons in the nucleus raphe dorsalis were identified by immunocytochemistry using antibodies to 5-hydroxytryptamine or GABA. The pattern of the 5-hydroxytryptamine and GABA immunostaining presented similar features: 5-hydroxytryptamine or GABA immunoreactive somata were fusiform or ovoid (15-20 micron) and positive dendritic profiles were found either without any connection with other nerve elements or in contact with one or several terminals. In addition, some 5-hydroxytryptamine nerve endings were apposed to 5-hydroxytryptamine immunoreactive cell bodies or dendrites; also some GABA-immunopositive terminals were in contact with GABA-immunopositive nerve cell bodies. On the other hand, GABA and 5-hydroxytryptamine patterns may be differentiated in several respects: the 5-hydroxytryptamine-reactive nerve cell bodies were more numerous than the GABA ones. Some small, round (8-10 micron) nerve cell bodies were reactive with GABA antiserum, but no neurons of this type were reactive with a 5-hydroxytryptamine antiserum; finally, GABA nerve terminals were more numerous than 5-hydroxytryptamine ones. In order to understand the relationship between GABA and 5-hydroxytryptamine neurons, radioautographic and immunocytochemical procedures were combined: 5-hydroxytryptamine and GABA immunocytochemistry was combined with radioautography of [3H]GABA and [3H]5-hydroxytryptamine uptake, respectively. Some nerve cell bodies, dendrites or terminals, which were 5-hydroxytryptamine-immunopositive, were also capable of accumulating [3H]GABA and, conversely, some GABA-immunopositive elements were capable of accumulating [3H]5-hydroxytryptamine. Moreover, several nerve elements were reactive with both glutamate decarboxylase and 5-hydroxytryptamine antisera. These data confirm in electron microscopy previous studies suggesting the coexistence of both GABA and 5-hydroxytryptamine in the same neurons. The presence of uptake mechanisms for GABA and 5-hydroxytryptamine may indicate the action of both neurotransmitters in the same neuron. On the other hand, the [3H]GABA-labelled nerve endings in contact with 5-hydroxytryptamine-positive dendrites or nerve cell bodies indicate the possibility of a GABAergic control of the activity of some 5-hydroxytryptamine neurons; this corroborates biochemical and electrophysiological studies whereby a trans-synaptic control of the 5-hydroxytryptamine neurons by GABA may be envisaged.