13 research outputs found
Pituitary androgen receptor signalling regulates prolactin but not gonadotrophins in the male mouse
Production of the androgen testosterone is controlled by a negative feedback loop within the hypothalamic-pituitary-gonadal (HPG) axis. Stimulation of testicular Leydig cells by pituitary luteinising hormone (LH) is under the control of hypothalamic gonadotrophin releasing hormone (GnRH), while suppression of LH secretion by the pituitary is controlled by circulating testosterone. Exactly how androgens exert their feedback control of gonadotrophin secretion (and whether this is at the level of the pituitary), as well as the role of AR in other pituitary cell types remains unclear. To investigate these questions, we exploited a transgenic mouse line (Foxg1 Cre/+; AR fl/y) which lacks androgen receptor in the pituitary gland. Both circulating testosterone and gonadotrophins are unchanged in adulthood, demonstrating that AR signalling is dispensable in the male mouse pituitary for testosterone-dependent regulation of LH secretion. In contrast, Foxg1 Cre/+; AR fl/y males have a significant increase in circulating prolactin, suggesting that, rather than controlling gonadotrophins, AR-signalling in the pituitary acts to suppress aberrant prolactin production in males
A giant exoplanet orbiting a very-low-mass star challenges planet formation models
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought
CARMENES: high-resolution spectra and precise radial velocities in the red and infrared
SPIE Astronomical Telescopes + Instrumentation (2018, Austin, Texas, United States
Dopamine Modulates Insulin Release and Is Involved in the Survival of Rat Pancreatic Beta Cells
Insulin Receptor Substrate 2 (IRS2)-Deficient Mice Show Sensorineural Hearing Loss That Is Delayed by Concomitant Protein Tyrosine Phosphatase 1B (PTP1B) Loss of Function
The insulin receptor substrate (IRS) proteins are key mediators of insulin and insulinlike growth factor 1 (IGF-1) signaling. Protein tyrosine phosphatase (PTP)-1B dephosphorylates and inactivates both insulin and IGF-1 receptors. IRS2-deficient mice present altered hepatic insulin signaling and β-cell failure and develop type 2–like diabetes. In addition, IRS2 deficiency leads to developmental defects in the nervous system. IGF1 gene mutations cause syndromic sensorineural hearing loss in humans and mice. However, the involvement of IRS2 and PTP1B, two IGF-1 downstream signaling mediators, in hearing onset and loss has not been studied. Our objective was to study the hearing function and cochlear morphology of Irs2-null mice and the impact of PTP1B deficiency. We have studied the auditory brainstem responses and the cochlear morphology of systemic Irs2−/−Ptpn1+/+, Irs2+/+Ptpn1−/−and Irs2−/−Ptpn1−/− mice at different postnatal ages. The results indicated that Irs2−/−Ptpn1+/+ mice present a profound congenital sensorineural deafness before the onset of diabetes and altered cochlear morphology with hypoinnervation of the cochlear ganglion and aberrant stria vascularis, compared with wild-type mice. Simultaneous PTP1B deficiency in Irs2−/−Ptpn1−/− mice delays the onset of deafness. We show for the first time that IRS2 is essential for hearing and that PTP1B inhibition may be useful for treating deafness associated with hyperglycemia and type 2 diabetes
Is there an optimal dose for dietary linoleic acid? Lessons from essential fatty acid deficiency supplementation and adipocyte functions in rats
Localization of the aromatase enzyme expression in the human pituitary gland and its effect on growth hormone, prolactin, and thyroid stimulating hormone axis
Insulin-Receptor Substrate-2 (IRS-2) Is Required for Maintaining Glucokinase and Glucokinase Regulatory Protein Expression in Mouse Liver
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Transit detection of the long-period volatile-rich super-Earth ν<sup>2</sup> Lupi d with CHEOPS
Exoplanets transiting bright nearby stars are key objects for advancing our
knowledge of planetary formation and evolution. The wealth of photons from the
host star gives detailed access to the atmospheric, interior, and orbital
properties of the planetary companions. Lupi (HD 136352) is a naked-eye
() Sun-like star that was discovered to host three low-mass planets
with orbital periods of 11.6, 27.6, and 107.6 days via radial velocity
monitoring (Udry et al. 2019). The two inner planets (b and c) were recently
found to transit (Kane et al. 2020), prompting a photometric follow-up by the
brand-new . Here, we report
that the outer planet d is also transiting, and measure its radius and mass to
be and , respectively.
With its bright Sun-like star, long period, and mild irradiation (5.7
times the irradiation of Earth), Lupi d unlocks a completely new region
in the parameter space of exoplanets amenable to detailed characterization. We
refine the properties of all three planets: planet b likely has a rocky mostly
dry composition, while planets c and d seem to have retained small
hydrogen-helium envelopes and a possibly large water fraction. This diversity
of planetary compositions makes the Lupi system an excellent laboratory
for testing formation and evolution models of low-mass planets