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Ovarian hormone deprivation impairs oxytocinergic neurons expression in paraventricular nucleus pre-autonomic neurons in rats

      Paraventricular nucleus (PVN) pre-autonomic oxytocinergic neurons (Posterior (P), ventromedial (VM) and dorsal cap (DC) subnuclei) are crucial to cardiovascular autonomic control and contains estrogen receptors. We aimed evaluate if ovarian hormones deprivation (OHD) can reduces oxytocin expression and produce changes in the arterial pressure. Female rats were divided into 2 groups; Ovariectomy was perfomed (OVX group) and 8 weeks later , arterial pressure (AP, mmHg) and heart rate (HR, bpm) were recorded. Brains were collected to oxytocin mRNA analysis (PCR-RT) and oxytocin imunoflurescence into PVN. OVX animals showed increase in mean AP (109 ± 2 vs 99 ± 3 mmHg), however, there was no change in heart rate (HR) (368 ± 6 vs 353 ± 5 bpm). In evaluation of HR variability by spectral analysis there were increase in LF (39.33 ± 5 vs 22.50 ± 3 nu) and decrease in HF (60.66 ± 5 vs 77.50 ± 3 nu). Baroreflex sensitivity, measured by sequence method, was reduced in OVX (0.73 ± 0.1 vs 1.76 ± 0.2 ms/mmHg). Oxytocin mRNA relative expression was reduced (0.92 ± 0.2 vs 1.95 ± 0.4 a.u) and there was decrease in density of neurons in P (19 ± 1.7 vs 26 ± 2.0), VM (35 ± 2.4 vs 49 ± 4.0) and DC (08 ± 0.8 vs 10 ± 0.8) subnuclei. OHD was able to develops hypertension and impairs autonomic cardiovascular control through decrease in oxytocin expression of pre-autonomic neurons in PVN. Financial Support: CAPES/Fapitec.
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