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Ovarian Steroid Regulation Of Tryptophan Hydroxylase Enzyme Level In The Midbrain Raphe In Ovariectomized Guinea Pigs, Zhidong Lu

Dissertations and Theses

Progesterone stimulates prolactin secretion in estrogen ( estradiol-17-~)primed monkeys and guinea pigs. It is hypothesized that the serotonin neural system plays a pivotol role in mediating the effect of progesterone on prolactin secretion. Indeed, progesterone, but not estrogen, increases serotonin levels in the midbrain raphe in guinea pigs. However, estrogen alone stimulates gene expression of the rate-limiting enzyme for serotonin synthesis, tryptophan hydroxylase (TPH), and progesterone supplement to the estrogen regimen has no additive effect, as indicated by TPH mRNA levels in monkeys. The discrepancy between ovarian steroid effects on the TPH mRNA level and the serotonin level might be …