Androgen-dependent stimulation of brain dopaminergic systems in the female European eel (Anguilla anguilla).

Dopamine (DA), a neurotransmitter present in all vertebrates, is involved in processes such as motor function, learning and behavior, sensory activities, and neuroendocrine control of pituitary hormone release. In the female eel, we analyzed how gonadal steroids regulate brain expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in the biosynthesis of DA. TH mRNA levels were assayed by quantitative real-time RT-PCR. TH-positive nuclei were also localized by in situ hybridization (ISH) and immunohistochemistry, and the location of TH nuclei that project to the pituitary was determined using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindicarbocyanine perchlorate retrograde tracing. Chronic in vivo treatment with testosterone increased TH mRNA specifically in the periglomerular area of the olfactory bulbs and in the nucleus preopticus anteroventralis (NPOav). NPOav was labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindicarbocyanine perchlorate, showing that this nucleus is hypophysiotropic in the eel. The nonaromatizable 5alpha-dihydrotestosterone gave identical results in both areas, whereas 17beta-estradiol had no stimulatory effect, showing that the observed stimulatory effects of testosterone were androgen dependent. In teleosts, DA neurons originating from the NPOav directly inhibit gonadotropic function, and our results indicate an androgen-dependent, positive feedback on this neuroendocrine control in the eel. In mammals, DA interneurons in the olfactory bulbs are involved in the enhancement of olfactory sensitivity and discrimination. Our results in the European eel suggest an androgen-dependent stimulation of olfactory processing, a sensory function believed to be important in eel navigation during its reproductive migration toward the oceanic spawning grounds. To our knowledge, this is the first evidence from any vertebrate of an androgen-dependent effect on DAergic activity in the olfactory bulbs, providing a new basis for understanding the regulation by gonadal steroids of central DAergic systems in vertebrates

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Detection of the anti-androgenic effect of endocrine disrupting environmental contaminants using in vivo and in vitro assays in the three-spined stickleback

We have previously developed a novel in vitro assay that utilises cultures of primed female stickleback kidney cells for the screening of potential androgenic and anti-androgenic environmental contaminants. Stickleback kidney cells are natural targets for steroid hormones and are able to produce a protein, spiggin, in response to androgenic stimulation. We undertook a combined in vivo/in vitro study where we used the magnitude of spiggin production as an endpoint to test the anti-androgenic properties of the pharmaceutical androgen antagonist flutamide and three environmental contaminants: the organophosphate insecticide fenitrothion, the urea-based herbicide linuron and the fungicide vinclozolin. In vitro, kidney cells were exposed to a range of concentrations [from 10-14M (2.5pg/L) up to 10-6M (280μg/L)] of the test compounds alone for determining agonist activities, or together with 10-8M (3μg/L) dihydrotestosterone (DHT) for determining antagonist activities. An in vivo flow-trough aquarium-based study was carried out in parallel. Female sticklebacks were exposed to a range of concentrations of the same chemicals alone or in combination with DHT (5μg/L) for 21 days. All of the compounds significantly inhibited DHT-induced spiggin production in a concentration-dependent manner in both the in vitro (FN≥FL≥LN>VZ) and in vivo (FN>FL≥VZ>LN) assays. Fenitrothion and flutamide inhibited spiggin production in vitro at a concentration as low as 10-12M (P<0.05), while linuron and vinclozolin inhibited DHT-induced spiggin production at concentrations of 10-10M (P<0.05) and 10-6M (P<0.001) respectively. Similarly, fenitrothion and flutamide were the most potent chemicals in vivo and significantly reduced DHT-induced spiggin production at a concentration of 10μg/L and 25μg/L respectively (P<0.01). Both linuron and vinclozolin induced a significant decrease in DHT-induced spiggin production at a concentration of 100μg/L when tested in vivo. In addition, kidney cell primary culture was used to test the (anti-)androgenic effects of the major environmental contaminants: oestradiol (E2), nonylphenol (NP) and bisphenol A (BPA) for the first time in teleosts. We observed that these compounds were able to significantly inhibit spiggin production at high doses (E2: 270μg/L; NP: 2.2μg/L; BPA: 2.3μg/L). When tested in the absence of DHT, none of the compounds showed a significant agonistic activity in either in vivo or in vitro assays. Overall, our data further demonstrate that kidney cell primary culture is a reliable and a sensitive screening tool for the detection of (anti-)androgenic compounds. In addition, our study represents the first attempt to develop a combined in vivo/in vitro screening strategy for assessing the effects of (anti-)androgenic endocrine disrupters

Effet d'hormones gonadotropes, in vitro, sur la concentration de l'adénosine monophosphate cyclique dans l'ovaire de l'anguille (Anguilla anguilla L.)

International audienc

\uc9tat sexuel et axe gonadotrope hypothalamo-hypophysaire chez les trois esp\ue8ces d\u27Anguilles de Tahiti (Anguilla marmorata, A. megastoma et A. obscura)

Volume: 10Start Page: 147End Page: 16

Dopaminergic inhibition of reproduction in teleost fishes: ecophysiological and evolutionary implications.

In many teleosts, dopamine (DA) exerts direct inhibitory control on gonadotropes, counteracting the stimulatory effect of gonadotropin-releasing hormone (GnRH) on gonadotropin release. This dual control by GnRH and DA has been demonstrated in various adult teleosts and has major implications for aquaculture. Because of its unique life cycle, the European eel has provided a powerful model for demonstrating the key role of DA in the control of puberty. Data from tetrapods suggest that the inhibitory role of DA on reproduction is not restricted to the teleosts. Thus, DA inhibitory control could represent an ancient evolutionary component in the neuroendocrine regulation of reproduction that may have been differentially maintained throughout vertebrate evolution. The intensity of DA inhibition, its main site of action, and its involvement in the control of puberty, seasonal reproduction, ovulation, spermiation, or even sex change may differ among classes of vertebrates, as well as within smaller phylogenetic units such as teleosts or mammals. An inhibitory role for DA has been reported also in some invertebrates, indicating that neuronal DA pathways may have been recruited in various groups of metazoa to participate in the control of reproduction. In addition to the incontestable GnRH neurons, the recruitment of DA neurons for the neuroendocrine control of reproduction provides an additional brain pathway for the integration of various species-specific, internal, and environmental cues. In teleosts, the plasticity of the DA neuroendocrine role may have contributed to their large diversity of biological cycles and to their successful adaptation to various environments

Un contre-pouvoir au contrôle de la reproduction par la GnRH chez les Poissons Téléostéens : l’inhibition dopaminergique. Rôle ancestral et conservation différentielle chez les Vertébrés ?

Chez les Mammifères, le contrôle neurohormonal des cellules gonadotropes hypophysaires est assuré par la gonadolibérine, GnRH. De nombreux travaux menés chez les Poissons Téléostéens montrent que ce contrôle unique de type stimulateur n’est pas une règle générale chez les Vertébrés. La première mise en évidence de l’implication d’un facteur neurohormonal inhibiteur, le « GRIF » (gonadotropin-release inhibiting factor), a été apportée par Peter et al., 1978 par des expériences de lésion cérébrale, chez le poisson rouge, induisant une décharge ovulatoire de LH. Plus tard, il a été démontré par des expériences in vivo et in vitro que le GRIF n’était autre que la dopamine, et des études neuroanatomiques ont confirmé que les neurones dopaminergiques de l’aire préoptique antérieure, projetant jusque dans l’hypophyse, correspondaient bien à ceux qui exerçaient une activité GRIF. Le rôle inhibiteur de la dopamine dans le contrôle de la LH et de l’ovulation ou de la spermiation a été étendu à de nombreux Téléostéens adultes, avec des applications en aquaculture ; toutefois, il n’est pas retrouvé chez toutes les espèces. À des étapes plus précoces de la gamétogenèse et en particulier dans le contrôle de la puberté, le rôle de la dopamine à été suggéré ou réfuté selon les espèces. L’Anguille, grâce à son cycle biologique original, a fourni un modèle favorable à la démonstration d’un rôle clé de la dopamine dans le contrôle de la puberté. La revue de travaux menés chez les Tétrapodes suggère que l’activité GRIF de la dopamine ne serait pas restreinte aux Téléosteéns, qu’elle pourrait avoir une origine évolutive ancienne et aurait été mise en oeuvre de façon différentielle au cours de l’évolution des Vertébrés

An antagonist to GnRH in the control of reproduction in teleost fish: dopaminergic inhibition. Ancestral origin and differential conservation within vertebrates ? [Un contre-pouvoir au contrôle de la reproduction par la GnRH chez les poissons téléostéens: l'inhibition dopaminergique. Rôle ancestral et conservation différentielle chez les Vertébrés.]

In mammals, the neurohormonal control of the pituitary gonadotropes is provided by the gonadoliberin GnRH. Several studies on teleost fish indicate that a single positive control by GnRH is not a general rule among vertebrates. Peter and colleagues presented the first evidence of an inhibitory neurohormonal factor, "GRIF" (gonadotropin-release inhibiting factor). They induced a preovulatory LH surge by injuring particular brain areas in the goldfish. Subsequent in vivo and in vitro studies identified dopamine as GRIF, and neuroanatomical investigations have demonstrated that dopaminergic neurones in the anterior preoptic area projecting to the pituitary represent the anatomical substrate for GRIF activity. An inhibitory role of dopamine on the control of LH and ovulation/spermiation has been evidenced in many adult teleosts, including its implications for aquaculture. However, dopamine does not play an inhibitory role in all adult teleosts. As regards the early stages of gametogenesis and especially the control of puberty, a role for dopamine has been suggested or rejected depending on species. The European eel has a unique life cycle with a long prepubertal stage, which has made it a useful model to demonstrate the key-role of dopamine in the control of puberty. Data from tetrapods suggest that the role of dopamine as a GRIF is not restricted to the teleosts, but that it may have an ancient evolutionary origin, and has been differentially conserved throughout vertebrate evolution