INVITRO LIVER CLEARANCE OF TRITIATED ESTRADIOL-17-BETA IN FEMALE RAT AFTER RETROCHIASMATIC TRANSECTION AND OVARIECTOMY

It was reported in a previous study that serum estradiol-17β (E2) was elevated in rats after retrochiasmatic transection (FC). Serum E2 was also higher in estradiol cypionate treated, ovariectomized (ovx) rats that had been subjected to FC than in those that had not. This suggested that increased secretion of E2 was not the only factor responsible for elevated serum E2 after FC. To ascertain the contribution of decreased metabolism of E2 to this response, liver tissue slices were incubated with 3H-estradiol-17β, and the rates of 3h uptake and conversion to water-soluble conjugates were measured. The rate of uptake of 3H by the tissue was not indicative of the rate of conjugate formation. Livers of rats with high serum E2 exhibited lower rates of 3h uptake than those of rats with low serum E2. Even so, the formation of 3H conjugates was greater in liver of rats with high serum E2. As hypothesized, livers of rats with FC formed conjugates at a significantly lower rate than those of similarly treated rats without FC. Thus, FC of an intact rat leads to an increase in serum E2 by increasing the secretion of E2, and apparently also by decreasing the rate of E2 metabolism by the liver. © 1978.