Gender differences of gene expression profiles in brain cardiovascular centers of WKY rats [hypothalamus]

Arterial pressure (AP) is lower in pre-menopausal women than in men of similar age. Pre-menopausal women exhibit a lower sympathetic outflow and a greater baroreceptor reflex, however molecular mechanisms for the gender differences of AP regulation are still not well understood. Since the hypothalmus is strongly functionnaly connected to the nucleus tractus solitarius (NTS), a pivotal region of the medulla oblongata for regulating the set-point of AP, we hypothesized that a different neuronal functions at the level of hypothalamus between men and women could contribute to the gender difference in cardiovascular homeostasis. Females Spontaneous Hypertensive Rats (SHRs) clearly exhibit lower AP levels than their male counterparts at similar age and their hypothalamus is characterized by a specific gene expression profile. This gender dependence of AP level is less marked in the normotensive strain, Wistar Kyoto rats (WKY). In this study, we investigated the gender-dependent gene expression profile of the hypothalamus of WKY rats by using microarray technique. 2 groups of adult WKY rats (9 weeks old) were formed : males (n=5) and females(n=5). For each rat, the whole hypothalamus was dissected and total RNAs were extracted. For each group, 100ng of total RNAs from each rats were pooled together before being processed in the microarray experiment.