Prolactin, a hormone involved in vertebrate parental care, is hypothesized to inhibit reproductive hypothalamic-pituitary-gonadal (HPG) axis activity during parenting, thus maintaining investment in the current brood as opposed to new reproductive efforts. While prolactin underlies many parental behaviors in birds, its effects on other reproductive behaviors, such as courtship, remain unstudied. How prolactin affects neuropeptide and hormone receptor expression across the avian HPG axis also remains unknown. To address these questions, we administered ovine prolactin (oPRL) or a vehicle control to both sexes in experienced pairs of the biparental rock dove (Columba livia), after nest removal at the end of incubation. We found that oPRL promoted parental responses to novel chicks and stimulated crop growth compared to controls, consistent with other studies. However, we found that neither courtship behaviors, copulation rates nor pair maintenance differed with oPRL treatment. Across the HPG, we found oPRL had little effect on gene expression in hypothalamic nuclei, but increased expression of FSHB and hypothalamic hormone receptor genes in the pituitary. In the gonads, oPRL increased testes size and gonadotropin receptor expression, but did not affect ovarian state or small white follicle gene expression. However, the oviducts of oPRL-treated females were smaller and had lower estrogen receptor expression compared with controls. Our results highlight that some species, especially those that show multiple brooding, may be able to maintain mating behavior despite elevated prolactin. Thus, mechanisms may exist for prolactin to promote investment in parental care without concurrent inhibition of reproductive function or HPG axis activity.
Urethane is used in rats and dogs and is recognized to minimally suppress cardiorespiratory function, but little is known about its impact in mouse models. The overall purpose of this study was to comprehensively compare cardiorespiratory function in mice anesthetized with urethane, compared to conscious state. 16-week old C57BL6/J mice (n=30,15 males, 15 females), underwent measurements while conscious and urethane-anesthetized. Hemodynamic parameters including heart rate variability (HRV), blood pressure (BP), heart rate (HR), and oxygen saturation (SpO2) were acquired using non-invasive (CODA and MouseOx) and invasive (Cardiac catheterization, Millar PVR-1030) techniques. All experiments were repeated with supplemental oxygen. Urethane decreased HRV and SpO2. Oxygen supplementation restored HRV and SpO2. We found no significant difference between invasive and non-invasive measurements of HRV, HR, BP, and SpO2. Urethane depressed BP in a sex-dependent manner. In this first report of the HRV response to urethane anesthesia in mice we found an anesthesia-induced decline in various cardiovascular parameters that is likely the result of urethane-induced hypoxemia. Changes characterizing the autonomic responsiveness to urethane stimuli in mice are described and should be considered when choosing the appropriate anesthetic agent. NIH1R21HD099573 and NIH 1R56HL152365. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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