Changes in levels of LH and FSH in the circulation were examined during repeated blood sampling in untreated rats and gonadectomized male and female rats treated with oestrogen, progesterone and thyroxine. Blood depletion induced a significant increase in levels of LH in steroid-treated rats but the increase was abolished when the depleted blood volume was replaced with egg albumen. The rise in LH was less dramatic in male than in female animals. In untreated rats, levels of LH either decreased or did not change with repeated phlebotomy. In contrast, the levels of FSH either did not alter or were lowered in all situations.
Animals Blood Volume