Abstract
The cardioprotective effects of female hormones/female sex are well‐described. In particular, several studies demonstrate the importance of female hormones on regulation of sympathetic outflow, a primary contributor to normal blood pressure as well as cardiovascular disease. Protective effects of ovarian hormones may include actions in the rostral ventrolateral medulla (RVLM), a brain region critical to sympathetic outflow and blood pressure. However, the time course and mechanisms by which sex‐differences contribute to excitation and inhibition of RVLM neurons are not fully elucidated; particularly in sexually immature animals, which lack higher levels of reproductive hormones. Therefore, we hypothesized that in the presence of lower levels of reproductive hormones, sexually immature females may exhibit increased glutamate (excitatory) receptors and decreased GABAA (inhibitory) receptors, indicative of an excitatory profile in the RVLM. To test our hypothesis, we obtained brain punches from the RVLM of four week old, male and female Sprague‐Dawley rats (n=3 ea), and processed them for western blotting. The NMDA (NR1) subunit was expressed in the RVLM of both sexes, but was expressed at a higher level in females compared to males (1.10±0.08 vs. 0.65±0.10 protein/GAPDH, respectively). The GABAAα1 subunit was also expressed in the RVLM of both sexes, but was expressed at lower levels in females compared to males (0.61±0.08 vs. 0.79±0.10 protein/GAPDH, respectively). These results suggest that prior to the onset of sexual maturity, a lower level of female hormones may increase the relative excitability of the RVLM and lead to greater sympathoexcitation in females compared to males. These experiments illustrate the importance of studying the time course and level of sexual maturity of animals in studies involving the influence of reproductive hormones. We are currently performing in vivo studies to examine the functional correlates of a greater excitatory profile in the RVLM of female rats, and to what extent sexual maturation influences the RVLM in both sexes.Support or Funding Information(HL096787‐07; AHA25810010)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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