Consequences of temperature-induced sex reversal on hormones and brain in Nile tilapia (Oreochromis niloticus).

Fish present a wide variety of sex determination systems ranging from strict genetic control (genetic sex determination, GSD) to strict environmental control (environmental sex determination, ESD). Temperature is the most frequent environmental factor influencing sex determination. Nile tilapia (Oreochromis niloticus) is characterized by GSD with male heterogamety (XY/XX), which can be overridden by exposure to high masculinizing temperatures. Sex reversed Nile tilapia (XX males; neomales) have been described in the wild and seem undistinguishable from XY males, but little is known about their physiology. The consideration of climate change urges the need to understand the possible physiological and behavioral consequences of such a sex reversal. The present study compared XX females, XY males and XX neomales for testis maturation, circulating sex -steroid concentrations as well as the size and number of neurons expressing arginine-vasotocin [AVT] and gonadotropin releasing hormone [GnRH] which are involved in sociosexual pathways. The results revealed that temperature-induced sex reversal does not affect testis maturation nor circulating sex steroid concentrations. Neomales show dramatically fewer GnRH1-immunoreactive (-ir) neurons than males and females, despite the observed normal testis physiology. Neomales also present fewer AVT-ir neurons in the magnocellular preoptic area than females and bigger AVT-ir neurons in the parvocellular POA (pPOA) compared to both males and females. The absence of consequences of sex reversal on testis development and secretions despite the reduced numbers of GnRH1 neurons suggests the existence of compensatory mechanisms in the hypothalamic-pituitary-gonadal axis, while the larger pPOA AVT neurons might predict a more submissive behavior in neomales.

Taste function assessed by electrogustometry in burning mouth syndrome: a case-control study.

OBJECTIVE: Idiopathic burning mouth syndrome (iBMS) is characterized by oral persistent pain without any clinical or biological abnormality. The aim of this study was to evaluate taste function in iBMS subjects and healthy controls. MATERIAL AND METHODS: Electrogustometric thresholds (EGMt) were recorded in 21 iBMS patients and 21 paired-matched controls at nine loci of the tongue assessing fungiform and foliate gustatory papillae function. Comparison of EGMt was performed using the nonparametric Wilcoxon signed-rank test. A correlation between EGMt and self-perceived pain intensity assessed using a visual analogic scale (VAS) was analyzed with the Spearman coefficient. The level of significance was fixed at P < 0.05. RESULTS: Mean EGMt were significantly increased with iBMS for right side of the dorsum of the tongue and right lateral side of the tongue (P < 0.05). In the iBMS group, VAS scores were significantly correlated to EGMt at the tip of the tongue (r = -0.59; P < 0.05) and at the right and left lateral sides of the tongue (respectively, r = -0.49 and r = -0.47; P < 0.05). CONCLUSION: These data depicted impaired taste sensitivity in iBMS patients within fungiform and foliate taste bud fields and support potent gustatory/nociceptive interaction in iBMS.

Effects of synthetic analogues of human opiorphin on rat brain opioid receptors.

Human opiorphin (Gln-Arg-Phe-Ser-Arg; QRFSR-peptide) is a physiological inhibitor of enkephalin-inactivating peptidases. We previously demonstrated that opiorphin can substitute for the classic mixture of peptidase inhibitors and greatly improves the specific binding and affinity of the enkephalin-related peptide [(3)H]MERF (Tyr-Gly-Gly-Phe-Met-Arg-Phe; YGGFMRF) for rat brain opioid receptors. To extend the metabolic stability of opiorphin in human plasma two functional derivatives were designed, i.e., Cys-[(CH(2))(6)]-QRF-[Ser-O-octanoyl]-R peptide (monomeric CC6-opiorphin) and its cystine-dipeptide (dimeric CC6-opiorphin) derivative. We found that, in homologous competition experiments, the affinity of [(3)H]MERF for rat brain opioid receptors was significantly increased in the presence of monomeric and dimeric CC6-opiorphin, compared to control-Tris buffer. In addition ten times lower concentrations (5 µM) than those required for native opiorphin (50 µM) were sufficient. In heterologous competition experiments, using unlabeled dynorphin(1-10), affinity increases were also observed: increases in binding were similar with either monomeric or dimeric CC6-opiorphin. Surprisingly, these opiorphin analogues displayed weak competitive effects on [(3)H]MERF binding to rat brain opioid receptors in the absence of unlabeled MERF, effects never observed for the native opiorphin. In conclusion, CC6-opiorphin compounds are certainly more potent than the native opiorphin in increasing the binding and the affinity of homologous and heterologous competition, but the binding enhancement occurs only at temperatures much higher than 0°C, specifically at 24°C.

Influence of domestication process on immune response to repeated emersion stressors in Eurasian perch (Perca fluviatilis, L.).

Domestication might be a possible way to reduce the physiological response to long-term stressors and deleterious effects on immunity. The present study aimed to evaluate the chronic immune response induced by repeated emersions and the possible impact of domestication by comparing farmed Eurasian perch with short (F1) and long (F4) captive-life history. In the first experiment, fish were exposed to a single emersion and physiological stress response was measured in the short term to characterize fish sensitivity to the tested stressor. Serum cortisol and glucose elevated within 6h post-stress and splenosomatic index (SSI) decreased within 48h, indicating that the species was affected by emersion stressor. In the second experiment, F1 and F4 generations were submitted to repeated water emersions (3 times/week during 44days). On day 9, 18 and 44, samplings were performed 48h post-stressor to highlight any sustained disruption of immune system. Serum cortisol, glucose, SSI and lysozyme activity were evaluated and serum proteome was analyzed using 2D-DIGE. Any of the tested variables were affected by repeated emersions and proteomic analysis only revealed that alpha-2 macroglobulins (a2Ms) were up-regulated in the serum of stressed individuals. Domestication also resulted in the up-regulation of five a2M isoforms and down-regulation of complement C3 and Ig light chain proteins, independently of any stressor exposure. In conclusion, the results suggested that repeated emersions are not severe stressors for Eurasian perch, probably explaining why domestication had no influence on fish responses. Changes associated with domestication are highly complex and certainly need further investigations.

Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis.

OBJECTIVE: To define imaging patterns of unilateral cerebellar hypoplasia (UCH), discuss possible pathophysiological mechanisms and underline the etiology and prognosis associated with these lesions. METHODS: In this retrospective study we reviewed the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with or without decreased transverse cerebellar diameter. The review included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity, and of the severity of the hypoplasia. Data from clinical and biological work-up and follow-up were obtained. RESULTS: Our series could be divided into two groups according to whether imaging features changed progressively or remained constant during follow-up. In Group 1 (n = 8), the progression of imaging features, echogenic cerebellar changes and/or hyposignal in T2*-weighted MR images were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (n = 18), imaging features remained constant during follow-up; UCH was associated with abnormal foliation in three proven cases of clastic lesions, a cystic lesion was noted in three cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome and, in the remaining cases, UCH remained unchanged, with no imaging pattern typical of hemorrhage. In 24 cases the infant was liveborn and follow-up was continued in 23, for a mean period of 3 years. Among these, neurological complications were identified in seven (in one of seven (at a mean of 46 months) in Group 1 and in six of 16 (at a mean of 35 months) in Group 2). The surface loss of cerebellar hemisphere was > 50% in 19/24 fetuses and the vermis was clearly normal in appearance in 19/24. Predisposing factors for fetal vascular insult were identified in eight cases: these included maternal alcohol addiction, diabetes mellitus, congenital cytomegalovirus infection and pathological placenta with thrombotic vasculopathy and infarctions. CONCLUSION: UCH is defined as a focal lesion of the cerebellum that may be secondary to hemorrhage and/or ischemic insult, suggesting a clastic origin, particularly when imaging follow-up reveals changes over time. UCH may also be a clue for the prenatal diagnosis of PHACE syndrome. The amount of surface loss of cerebellar hemisphere does not correlate with poor prognosis. UCH with normal vermis is often associated with normal outcome.

Sperm quality analysis in XX, XY and YY males of the Nile tilapia (Oreochromis niloticus).

In Nile tilapia (Oreochromis niloticus), individuals with atypical sexual genotype are commonly used in farming (use of YY males to produce all-male offspring), but they also constitute major tools to study sex determinism mechanisms. In other species, sexual genotype and sex reversal procedures affect different aspects of biology, such as growth, behavior and reproductive success. The aim of this study was to assess the influence of sexual genotype on sperm quality in Nile tilapia. Milt characteristics were compared in XX (sex-reversed), XY and YY males in terms of gonadosomatic index, sperm count, sperm motility and duration of sperm motility. Sperm motility was measured by computer-assisted sperm analysis (CASA) quantifying several parameters: total motility, progressive motility, curvilinear velocity, straight line velocity, average path velocity and linearity. None of the sperm traits measured significantly differed between the three genotypes. Mean values of gonadosomatic index, sperm concentration and sperm motility duration of XX, XY and YY males, respectively ranged from 0.92 to 1.33%, from 1.69 to 2.22 ×10(9) cells mL(-1) and from 18'04″ to 27'32″. Mean values of total motility and curvilinear velocity 1 min after sperm activation, respectively ranged from 53 to 58% and from 71 to 76 µm s(-1) for the three genotypes. After 3 min of activity, all the sperm motility and velocity parameters dropped by half and continued to slowly decrease thereafter. Seven min after activation, only 9 to 13% of spermatozoa were still progressive. Our results prove that neither sexual genotype nor hormonal sex reversal treatments affect sperm quality in male Nile tilapias with atypical sexual genotype.

[Diagnostic investigations for an unexplained developmental disability]. / Stratégie d'exploration d'une déficience intellectuelle inexpliquée.

Developmental disability/mental retardation is a major public health problem and a common cause of consultation in pediatrics, neuropediatrics, and genetics. Etiologies of mental retardation are highly heterogeneous. Diagnostic strategies have been explored in a small number of consensus publications, essentially from English-speaking countries. In these publications, the utility of the conventional karyotype, fragile X screening, metabolic workup, and brain imaging were discussed. Recently, investigations in mental disabilities have been dramatically modified by molecular cytogenetics and the emergence of new metabolic pathologies. Based on the published experiments, the Reference centers for rare disease network "mental deficiencies with rare causes" elaborated an updated protocol for the investigation of nonsyndromal mental disability that takes into account recent innovations in genetics and genomics. Whenever local facilities make it possible, we recommend array CGH investigation as the first step or, when CGH is not available, a combination of classic karyotype with systematic screening of telomeric and interstitial rearrangements by MLPA, fragile X screening in both sexes, and a reorientation of metabolic screening toward certain diseases that have recently been described: congenital disorders of glycosylation (CDG), thyroid hormone carrier deficiency, and creatine metabolism deficiency. We recommend MRI imaging only if head size is abnormal, if neurological examination is abnormal, or regression occurs if walking is not achieved by 2 years, or if development is severely delayed.

Physiological and proteomic evidences that domestication process differentially modulates the immune status of juvenile Eurasian perch (Perca fluviatilis) under chronic confinement stress.

The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles (Perca fluviatilis) submitted to chronic confinement. Briefly, F1 and F4 generations were confined into small-size tanks and sampled 7 and 55 days after stocking. Cortisol and glucose levels as well as lysozyme activity and immunoglobulin level were evaluated in the serum. Spleen Somatic Index and spleen ROS production were also measured. A proteomic analysis was performed on serum sampled on day 7. Finally, both generations were genetically characterized using a microsatellite approach. Globally, results revealed that chronic confinement did not elicit a typical stress response but resulted in a prolonged immune stimulation. Proteomic results suggested that domestication process influenced the immune status of perch submitted to chronic confinement as the F1 confined fish displayed lower abundance of C3 complement component, transferrin and Apolipoprotein E. Microsatellite data showed a strong genetic drift as well as reduced genetic diversity, allelic number and heterozygosity along with domestication process. The present work is the first to report that fish under domestication can develop an immune response, assessed by a combined approach, following recurrent challenges imposed by captive environment despite a reduced genetic variation.

Does domestication process affect stress response in juvenile Eurasian perch Perca fluviatilis?

The objective was to evaluate the impact of domestication process on the physiological stress response of cultured Eurasian perch confronted to a chronic stress situation. Briefly, F1 and F4 juveniles were submitted to chronic confinement and investigated on days 5, 15 and 30. Capture and 15min-anesthesia were imposed on fish to assess the effect of preceding confinement on acute stress response. On day 30, the fish were finally challenged with Aeromonas hydrophila and sampled after 5 and 10 days for immune parameter measurements. Cortisol and glucose levels were not affected by confinement but increased significantly after acute stressor exposure. Moreover, cortisol rise following capture and anesthesia was higher in F1 confined-fish, suggesting that they have previously been affected by chronic confinement. A higher HSP70 level was also observed on day 30 in F1 confined-juveniles. During bacterial challenge, regardless of confinement level, F4 juveniles displayed higher lysozyme activity and agglutination response than F1 which may indicate a higher immune capacity in domesticated fish. In conclusion, chronic confinement stressor induced few physiological responses but may increase the responsiveness to other aquacultural stressors. Domestication process also seems to improve chronic stress resistance, growth as well as the immune status of the fish.

Systemically active human opiorphin is a potent yet non-addictive analgesic without drug tolerance effects.

Human opiorphin QRFSR-peptide protects enkephalins from degradation by human neutral endopeptidase (hNEP) and aminopeptidase-N (hAP-N) and inhibits pain perception in a behavioral model of mechanical acute pain (1). Here, using two other pain rat models, the tail-flick and the formalin tests, we assess the potency and duration of the antinociceptive action of opiorphin with reference to morphine. The occurrence of adverse effects with emphasis on the side-effect profile at equi-analgesic doses was compared. We demonstrate that opiorphin elicits minimal adverse morphine-associated effects, at doses (1-2 mg/kg, i.v.) that produce a comparable analgesic potency in both spinally controlled thermal-induced acute and peripheral chemical-induced tonic nociception. The analgesic response induced by opiorphin in the formalin-induced pain model preferentially requires activation of endogenous mu-opioid pathways. However, in contrast to exogenous mu-opioid agonists such as morphine, opiorphin, does not develop significant abuse liability or antinociceptive drug tolerance after subchronic treatment. In addition, anti-peristaltism was not observed. We conclude that opiorphin, by inhibiting the destruction of endogenous enkephalins, which are released according to the painful stimulus, activates restricted opioid pathways specifically involved in pain control, thus contributing to a greater balance between analgesia and side-effects than found with morphine. Therefore, opiorphin could give rise to new analgesics endowed with potencies similar to morphine but with fewer adverse effects than opioid agonists. Its chemical optimization, to generate functional derivatives endowed with better bioavailability properties than the native peptide, could lead to a potent class of physiological type analgesics.

Human opiorphin is a naturally occurring antidepressant acting selectively on enkephalin-dependent delta-opioid pathways.

Human opiorphin protects enkephalins from degradation by human neutral endopeptidase and aminopeptidase-N and inhibits pain perception in various behavioral rodent models of pain via endogenous enkephalin-related activation of opioidergic pathways. In addition to pain control, endogenous opioid pathways are also implicated in the modulation of emotion-related behaviors. Thus, we explored the dose-dependent motivational responses induced by opiorphin using the forced swim test, the standard rat model of depression. In addition, to further understand the endogenous events triggered by opiorphin, we investigated the specific involvement of mu- or delta-opioid receptor-dependent pathways. In parallel, the locomotor activity test was used to detect possible sedation or hyperactivity. Here, we report for the first time that at 1-2 mg/kg i.v. doses, opiorphin elicited antidepressant-like effects by activating endogenous delta-opioidergic pathways, since that activation was reversed by the selective delta-opioid antagonist naldrindole (10 mg/kg i.p.). The antidepressive behavioral responses exerted by opiorphin are specific at systemically active doses. Treated-rats did not develop either hypo- or hyper-active responses in a locomotor test or amnesic behavioral response in the passive avoidance rat model. In addition, opiorphin did not induce either anxiolytic-, or anxiogenic-like responses in the conditioned defensive burying test. Taking the data together, we conclude that opiorphin is able to elicit antidepressant-like effects, mediated via delta-opioid receptor-dependent pathways, by modulating the concentrations of endogenous enkephalin released in response to specific physical and/or psychological stimuli. Thus, opiorphin or optimized derivatives is a promising single candidate to treat disorders that include both pain and mood disorders, particularly depression.

Ovarian steroidogenesis inhibition by constant photothermal conditions is caused by a lack of gonadotropin stimulation in Eurasian perch.

In fish, the reasons for the inhibition of reproduction by constant photothermal conditions of rearing are far from clear. In an in vivo experiment, two groups of females reared under natural (4-28 degrees C) or constant photothermal conditions (20-22 degrees C, photoperiod 12/12) were investigated for gonad development, sex-steroids (testosterone-T, 17-beta-estradiol-E2 and 11 Keto-Testosterone-11KT) dynamics and brain aromatase activity in January, February and March. Two days before each sampling date, a group of females reared under constant conditions was injected with HCG (Human Chorionic Gonadotropin: 100 UI/kg) and evaluated for the same parameters. In addition, in vitro ovarian steroidogenesis capacity for each female was determined with or without stimulation by HCG and/or IGF-1 (Insulin-like Growth Factor-1). The results indicate that vitellogenesis stage is the limit ovarian stage never reached in females submitted to constant photothermal conditions. This was associated with gonadogenesis delay and low levels of circulating sex-steroids (T, E2 and 11KT). Nevertheless, HCG injections partly counteracted the plasma steroid deprivation, indicating that ovaries from fish reared under constant photothermal conditions suffer from a lack of gonadotropin stimulation, maybe caused by plasma LH suppression. Such finding was confirmed by the in vitro ovary incubation test. HCG and IGF-1 treatments induced broad testosterone and 17-beta-estradiol elevations and the exposure to constant photothermal conditions, in some cases, decreased that response to HCG. In conclusion, we show that the inhibition of reproductive cycle in Eurasian perch females by constant photothermal conditions of rearing may be related to lower sex-steroid levels and to an inhibition of ovarian regulation by gonadotropins (at least LH), probably stopping gonadogenesis before vitellogenesis stage.

Clinical, electrophysiological and genetic studies of two families with mutations in the GDAP1 gene.

Mutations in the gene for the ganglioside-induced-differentiation-associated-protein 1 on 8q21 were recently reported to cause autosomal recessive Charcot-Marie-Tooth sensorimotor neuropathy. We report a detailed clinical, electrophysiological and genetic study of two young patients harbouring missense GDAP1 mutations. The two patients presented severe neuropathy with an early onset. One of the mutations (Tyr279Cys) has never been hitherto reported. Electrophysiological investigations suggested a predominant axonal damage in both patients. Despite the similitude of the type of mutations and electromyographic features, the clinical course was different for the patients, highlighting the complexity of genotype/phenotype relationships among GDAP1 mutations.

Sex steroid dynamics during embryogenesis and sexual differentiation in Eurasian perch, Perca fluviatilis.

It is widely accepted that sex steroid hormones play an important and a specific role during the process of sex differentiation in fish. In order to describe the role of the three main sex steroid hormones (testosterone--T, 17beta-estradiol--E2 and 11keto-testosterone--11KT) during embryogenesis and sex differentiation in Eurasian perch, Perca fluviatilis, eggs, larvae and juveniles originating from two mixed-sex and two all-female progenies were regularly sampled from fertilization to hatching (D0) and from hatching to day 70 post-hatching (D70). Just after spawning, a significant amount of sex steroids [T (1634.2pgg(-1)), E2 (554.4pgg(-1)) and 11KT (1513.2pgg(-1))] was measured in non-fertilised eggs suggesting a maternal transmission of these steroids. From D2 to D70 post-hatching, E2 levels were significantly higher in mixed-sex progenies (median: 725.7pgg(-1)) than in all-female progenies (156.2pgg(-1)) and significantly increased after the onset of the histological differentiation of the gonad in both progenies (D35). Levels of 11KT were significantly higher in mixed-sex (median: 431.5pgg(-1)) than in all-female progenies (below the limit of assay detection) and significantly increased at D35 in all-female progenies (median value: 343.2pgg(-1)). Mean 11KT to E2 ratio was six-fold higher in mixed-sex progenies (1.35) than in all-female progenies (0.24). The data suggest that the 11-oxygenated androgen (11KT) plays a major role in the male differentiation process, and that sex differentiation in Eurasian perch is probably determined by the 11KT to E2 ratio.

Toxicokinetic and toxicodynamic analyses of Androctonus australis hector venom in rats: optimization of antivenom therapy.

This paper reports the simultaneous determination of toxicokinetic and toxicodynamic properties of Androctonus australis hector venom, in the absence and presence of antivenom (F(ab')(2) and Fab), in envenomed rats. After subcutaneous injection of the venom, toxins showed a complete absorption phase from the site of injection associated with a distribution into a large extravascular compartment. The injection of Fab and F(ab')(2) induced the neutralization of venom antigens in the blood compartment, as well as the redistribution of venom components from the extravascular compartment to the blood compartment. Interestingly, F(ab')(2) and Fab showed distinct efficiencies depending on their route of injection. F(ab')(2) induced a faster venom neutralization and redistribution than Fab when injected intravenously. Fab was more effective than F(ab')(2) by the intramuscular route. The hemodynamic effects of Aah venom were further investigated. Changes in mean arterial pressure and heart rate were observed in parallel with an upper airway obstruction. Fab was more effective than F(ab')(2) for preventing early symptoms of envenomation, whatever their route of administration. Intraperitoneal injection of F(ab')(2) and Fab was similar for the prevention of the delayed symptoms, even after a late administration. Fab was more effective than F(ab')(2) in the inhibition of airway resistance, independent of the route and time of administration. These results show that the treatment for scorpion stings might be improved by the intravascular injection of a mixture of Fab and F(ab')(2). If antivenom cannot be administered intravenously, Fab might be an alternative as they are more effective than F(ab')(2) when injected intramuscularly.

[Risk factors for Abacavir-induced hypersensibility syndrome in the "real world"]. / Facteurs de risque de syndrome d'hypersensibilité à l'Abacavir en pratique clinique de routine.

UNLABELLED: Abacavir (ABC) is a generally well-tolerated NRTI. However, up to 5% of patients may develop hypersensitivity syndrome (HSS) within the first weeks of treatment. The objectives of this study were to describe the side effects of ABC, to evaluate the incidence of the ABC-HSS, and to identify the risk factors of HSS after first exposure to ABC in a cohort of patients followed up in a university HIV clinic. METHODS: The charts of all HIV-infected patients who started ABC between February 1998 and May 2002 were reviewed. HSS was defined as the onset, within 8 weeks of ABC initiation, of either a skin rash associated with at least one of the following symptoms (fever, gastrointestinal symptoms, respiratory symptoms, myalgia, malaise) or at least three of the above symptoms in the absence of rash. A multivariate logistic regression analysis was performed to identify risk factors of HSS. RESULTS: Of the 191 patients studied (134 M, 57 F, mean age 39 years), 53 (27.8%) presented with manifestations that were regarded as potential side-effects of ABC. Ten (5.2%) developed HSS, none of whom died. Two factors were independently associated with an increased risk of HSS: history of allergy to nevirapine (OR 8.1, 95% CI 1.6-40.5, p = 0.02), and being naïve to ART (OR 5.8, 95% CI 1.2-28.5, p = 0.04). CONCLUSION: This study "in the real world" confirms that the incidence of ABC-induced HSS is of about 5%. It also confirms that HSS occurs more frequently in patients with a history of allergy to nevirapine and in ART-naïve patients.

The endogenous androgen-regulated sialorphin modulates male rat sexual behavior.

In sexually mature male rats, sialorphin is synthesized under androgenic control and its surge endocrine secretion is evoked in response to environmental acute stress. These findings led us to suggest that this signaling mediator might play a role in physiological and behavioral integration, especially reproduction. The present study investigates the effects induced by sialorphin on the male sexual behavior pattern. Intact male rats were treated in acute mode, with sialorphin at the 0.3, 1, and 3 microg/kg doses, before being paired with receptive female for 45 min. The data obtained show that sialorphin increased, in a dose-related manner, the occurrence of intromissions across the successive ejaculatory sequences. The rats treated with the highest 3 microg/kg dose significantly ejaculated less often compared to controls; however, 80% of them achieved up to three ejaculations. Further analyses of mount bouts for rats achieving three ejaculations reveal that there were significant stimulatory effects of sialorphin, at all doses, on the frequency of intromissions before ejaculation and on the propensity of males to engage in investigatory behavior directed to the female during the post-ejaculatory interval. Thus, sialorphin has the ability to modulate, at doses related to physiological circulating levels, the male rat mating pattern, that is, exerting a dual facilitative or inhibitory dose-dependent effect on the sexual performance, while stimulating the apparent sexual arousal or motivation. These findings led us to speculate that the endogenous androgen-regulated sialorphin helps modulate the adaptative balance between excitatory and inhibitory mechanisms serving appropriate male rat sexual response, depending on the context.

The proprotein convertase PC2 is involved in the maturation of prosomatostatin to somatostatin-14 but not in the somatostatin deficit in Alzheimer's disease.

A somatostatin deficit occurs in the cerebral cortex of Alzheimer's disease patients without a major loss in somatostatin-containing neurons. This deficit could be related to a reduction in the rate of proteolytic processing of peptide precursors. Since the two proprotein convertases (PC)1 and PC2 are responsible for the processing of neuropeptide precursors directed to the regulated secretory pathway, we examined whether they are involved first in the proteolytic processing of prosomatostatin in mouse and human brain and secondly in somatostatin defect associated with Alzheimer's disease. By size exclusion chromatography, the cleavage of prosomatostatin to somatostatin-14 is almost totally abolished in the cortex of PC2 null mice, while the proportions of prosomatostatin and somatostatin-28 are increased. By immunohistochemistry, PC1 and PC2 were localized in many neuronal elements in human frontal and temporal cortex. The convertases levels were quantified by Western blot, as well as the protein 7B2 which is required for the production of active PC2. No significant change in PC1 levels was observed in Alzheimer's disease. In contrast, a marked decrease in the ratio of the PC2 precursor to the total enzymatic pool was observed in the frontal cortex of Alzheimer patients. This decrease coincides with an increase in the binding protein 7B2. However, the content and enzymatic activity of the PC2 mature form were similar in Alzheimer patients and controls. Therefore, the cortical somatostatin defect is not due to convertase alteration occuring during Alzheimer's disease. Further studies will be needed to assess the mechanisms involved in somatostatin deficiency in Alzheimer's disease.

The anti-HIV pentameric pseudopeptide HB-19 is preferentially taken up in vivo by lymphoid organs where it forms a complex with nucleolin.

The HB-19 pseudopeptide 5[Kpsi(CH(2)N)PR]-TASP, psi(CH(2)N) for reduced peptide bond, is a specific inhibitor of HIV infection in different CD4(+) cell lines and in primary T-lymphocytes and macrophages. It blocks virus-particle attachment to permissive cells by binding and forming a stable complex with nucleolin expressed on the cell surface. Here, we have investigated the tissue distribution of the tritiated HB-19 by using beta-radio imager whole-body mapping in rats. A rapid, selective, and stable distribution and accumulation of the systematically administered HB-19 was demonstrated within the spleen, liver, bone, and kidney as soon as 5 min following its administration. No apparent uptake of HB-19 occurred in the brain and the muscle tissue. Interestingly and despite its rapid clearance from the blood, at 24 h postexposure a significant proportion of HB-19 was still recovered from target organs, of which 16-37% could be accounted for intact pseudopeptide. The elimination of HB-19 mainly occurred by renal glomerular filtration and most of the excreted radioactivity appeared to be HB-19 metabolites. Finally, injection of the biotin-labeled HB-19 pseudopeptide but not its control counterpart allowed the recovery of the HB-19-nucleolin complex from the liver, spleen, thymus, and bone marrow, thus indicating that the in vivo molecular target of HB-19 is surface nucleolin. Our results demonstrate the preferential uptake and stability of HB-19 in lymphoid organs that are the site of HIV propagation.

The transcriptional response to androgens of the rat VCSA1 gene is amplified by both binary and graded mechanisms.

In higher eukaryotes, gene expression can be highly modified in response to small variations of circulating hormonal inducers. To determine the mechanisms responsible for the 100- to 200-fold enhancement of expression of an androgen-regulated gene, VCSA1, in the acinar cells of rat submandibular glands during puberty, we performed a detailed analysis of VCSA1 expression at the single cell level. Using in situ detection of mature and primary VCSA1 transcripts, we show that VCSA1 expression is activated in only a small proportion of differentiated acinar cells in the presence of low levels of circulating androgens in prepubescent and in castrated males, as well as in females. During the time course of sexual maturation in males, we demonstrate an increase in the proportion of acinar cells expressing VCSA1 and an increase in VCSA1 heterogeneous nuclear RNA and mRNA content in the positive cell population. Finally, we show that changes in the methylation pattern of VCSA1 are correlated with VCSA1 transcriptional activation. These results demonstrate that androgens can, in physiological conditions, elicit both a binary and a graded response. They also provide evidence that the range of gene regulation may be expanded by a transcriptional repression in a majority of cells under basal conditions.