Central control of hepatic steroid metabolism: effect of discrete hypothalamic lesions.

The effects of various hypothalamic lesions on hepatic steroid metabolism in adult rats were investigated. It was found that frontal deafferentation at the retrochiasmatic and suprachiasmatic level resulted in a complete "feminization" of hepatic steroid metabolism in male rats. Such an effect was also seen when lesions involving mainly the anterior periventricular hypothalamic area and the suprachiasmatic nucleus were performed in male rats. Midline lesions, anterior to the suprachiasmatic nucleus, on the other hand, did not result in any significant effects. A moderate degree of "feminization" was obtained after bilateral lesions involving mainly the nucleus interstitialis striae terminalis but including also parts of the anterior commissure. Small lesions in the lateral preoptic area were, however, without effect. No effects were seen of analogous lesions in female rats in any of the cases studied. The present findings suggest that a region including the anterior hypothalamic periventricular area, the suprachiasmatic nucleus and adjacent areas is involved in the control of hepatic steroid metabolism. It is postulated that the neuronal cell bodies that produce a factor with an inhibitory effect on the secretion of "feminizing factor" have their origins in this area of the hypothalamus, or, alternatively, may send axons through this area to the basal hypothalamus and thus directly or indirectly influence the anterior pituitary gland.