Project description:Hypothalamic gonadotropin-releasing hormone (GnRH) neurons are central regulators of fertility and integrate endogenous hormonal status with environmental cues to ensure reproductive success. Here, we found that extra-hypothalamic GnRH neurons in the olfactory bulb of adult mice and humans (GnRHOB) can mediate social recognition. We show that GnRHOB neurons extend neurites into the vomeronasal organ and olfactory epithelium and project to the hypothalamic median eminence. We demonstrate that male GnRHOB neurons express vomeronasal and olfactory receptors, are activated by female odors in vivo, and mediate gonadotropin release in response to female urine. We find that male preference for female odors is enhanced upon chemogenetic activation of GnRHOB neurons and is impaired after genetic inhibition or ablation of these cells and relies on GnRH signaling in the posterodorsal medial amygdala. Taken together, these results establish GnRHOB neurons as a central regulatory hub regulating fertility, sex recognition, and mating in males.
Project description:Fertility critically depends on the gonadotropin-releasing hormone (GnRH) pulse generator, a neural construct comprised of hypothalamic neurons coexpressing kisspeptin, neurokoinin-B and dynorphin. Here, using mathematical modeling and in vivo optogenetics we reveal for the first time how this neural construct initiates and sustains the appropriate ultradian frequency essential for reproduction. Prompted by mathematical modeling, we show experimentally using female estrous mice that robust pulsatile release of luteinizing hormone, a proxy for GnRH, emerges abruptly as we increase the basal activity of the neuronal network using continuous low-frequency optogenetic stimulation. Further increase in basal activity markedly increases pulse frequency and eventually leads to pulse termination. Additional model predictions that pulsatile dynamics emerge from nonlinear positive and negative feedback interactions mediated through neurokinin-B and dynorphin signaling respectively are confirmed neuropharmacologically. Our results shed light on the long-elusive GnRH pulse generator offering new horizons for reproductive health and wellbeing.SIGNIFICANCE STATEMENT The gonadotropin-releasing hormone (GnRH) pulse generator controls the pulsatile secretion of the gonadotropic hormones LH and FSH and is critical for fertility. The hypothalamic arcuate kisspeptin neurons are thought to represent the GnRH pulse generator, since their oscillatory activity is coincident with LH pulses in the blood; a proxy for GnRH pulses. However, the mechanisms underlying GnRH pulse generation remain elusive. We developed a mathematical model of the kisspeptin neuronal network and confirmed its predictions experimentally, showing how LH secretion is frequency-modulated as we increase the basal activity of the arcuate kisspeptin neurons in vivo using continuous optogenetic stimulation. Our model provides a quantitative framework for understanding the reproductive neuroendocrine system and opens new horizons for fertility regulation
Model is encoded by Johannes and submitted to BioModels by Ahmad Zyoud.
Project description:Sex differences in liver gene expression are dictated by sex-differences in circulating growth hormone (GH) profiles. Presently, the pituitary hormone dependence of mouse liver gene expression was investigated on a global scale to discover sex-specific early GH response genes that might contribute to sex-specific regulation of downstream GH targets and to ascertain whether intrinsic sex-differences characterize hepatic responses to plasma GH stimulation. RNA expression analysis using 41,000-feature microarrays revealed two distinct classes of sex-specific mouse liver genes: genes subject to positive regulation (class-I) and genes subject to negative regulation by pituitary hormones (class-II). Genes activated or repressed in hypophysectomized (Hypox) mouse liver within 30-90min of GH pulse treatment at a physiological dose were identified as direct targets of GH action (early response genes). Intrinsic sex-differences in the GH responsiveness of a subset of these early response genes were observed. Notably, 45 male-specific genes, including five encoding transcriptional regulators that may mediate downstream sex-specific transcriptional responses, were rapidly induced by GH (within 30min) in Hypox male but not Hypox female mouse liver. The early GH response genes were enriched in 29 male-specific targets of the transcription factor Mef2, whose activation in hepatic stellate cells is associated with liver fibrosis leading to hepatocellular carcinoma, a male-predominant disease. Thus, the rapid activation by GH pulses of certain sex-specific genes is modulated by intrinsic sex-specific factors, which may be associated with prior hormone exposure (epigenetic mechanisms) or genetic factors that are pituitary-independent, and could contribute to sex-differences in predisposition to liver cancer or other hepatic pathophysiologies.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.
Project description:To quantify gene expression differences in olfactory epithelium between the mouse (Mus musculus) and the Nile rat (Arvicanthis niloticus), paired-end RNA sequencing (RNA-seq) was used to profile olfactory epithelium transcriptomes of six Nile rats and six mice (C57BL/6J) (one male and one female at the age of 8, 12, and 16 weeks for each species).
Project description:Naked mole rats live in eusocial colonies where subordinates help a single dominant female and a few males to breed. We investigated the genome-wide regulatory mechanisms underlying their reproductive division of labor by examining brain and gonad transcriptomes and DNA-methylomes. Subtle expression differences were observed between brains of dominants and subordinates, but differentially expressed genes clustered consistently in a module with similar function for both sexes. Gonadotropin-releasing hormone (GNRH1) was central in this module and linked with stress-response genes such as neuropeptide Y and corticotrophin-releasing hormone. Breeder-subordinate modifications in DNA methylation were substantial in male brains and associated with the GNRH1 module. The GNRH1-regulated estrogen synthesis pathway was completely blocked in subordinate ovaries and sperm-related genes were significantly down-regulated in subordinate testes. Our results indicate that reproductive suppression is based on hormonal- and stress-related control by the dominant female, but with significant differences in molecular mechanisms between males and females.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility. Gene expression was measured in whole testis from males aged 62-86 days. Samples include 190 first generation lab-bred male offspring of wild-caught mice from the Mus musculus musculus - M. m. domesticus hybrid zone.