The effect of testosterone in partially hepatectomized female rats

Estradiol and testosterone levels in patients undergoing partial hepatectomy. A possible signal for hepatic regeneration?

In five adult male patients undergoing a 40-60% partial hepatectomy, serum sex hormone levels before and after hepatic resection were determined. Blood was drawn immediately prior to each surgical procedure and at specified time points postoperatively. Compared to hormone levels found prior to surgery, following major hepatic resection, estradiol levels increase at 24 and 48 hr, while testosterone levels decline, being significantly reduced at 96 and 144 hr. These data demonstrate that adult males who undergo a 40-60% partial hepatectomy experience alterations in their sex hormone levels similar to those observed in male rats following a 70% hepatectomy. These changes in sex hormone levels have been associated in animals with an alteration of the sex hormone receptor status of the liver that is thought to participate in the initiation of the regenerative response. These studies suggest, but do not prove, that in man, as in the case of the rat, sex hormones may participate in the initiation of or at least modulate in part the regenerative response that occurs following a major hepatic resection.

Interference of sex-related factors in the response of liver cells to experimental mitotic stimuli

Stimulation of liver cell multiplication was obtained under two different experimental conditions. (1) A single injection of casein solution resulted in (a) an identical synchronized mitotic wave response in 10-day old male and female rats and (b) a significantly lower response in adult male rats compared to females, a difference which was reduced by castration of males at birth but essentially maintained if animals were operated when 10 days old. (2) Partial hepatectomy shortly after puberty resulted in active hepatocyte multiplication occurring 3 hr earlier in females were ovariectomized at birth and significantly reduced when they were spayed at a later age. Hepatocytes of castrated females entered actively into S phase 2 hr later than the sham-operated controls. Unilateral ovariectomy on the other hand indicated that during compensatory and/or hypercompensatory activity of the single ovary there was a maximum difference between the male and female rate of [3H]thymidine uptake in liver nuclei 20 hr after hepatectomy. A further kinetic study (t = 25, 30,40, 65, 90 hr) indicated no significant sex-related difference in the number of S phases per 10,000 cells. The DNA content of regenerating versus control livers was comparable in both sexes at t = 22 and 90 hr but higher in females at t = 40 and 65 hr. A possible early postnatal interference of certain hormonal mechanisms in the receptivity to mitotic stimuli is postulated and discussed.