Ovarian steroid regulation of tryptophan hydroxylase mRNA expression in rhesus macaques

Melanie Pecins-Thompson, Nancy A. Brown, Steven G. Kohama, Cynthia L. Bethea

Research output: Contribution to journalArticlepeer-review

159 Scopus citations


Progesterone (P) stimulates prolactin secretion through an unknown neural mechanism in estrogen (E)-primed female monkeys. Serotonin is a stimulatory neurotransmitter in prolactin regulation, and this laboratory has shown previously that E induces progestin receptors (PR) in serotonin neurons. Therefore, we questioned whether E and/or E + P increased serotonin neural function. The expression of mRNA for tryptophan hydroxylase (TPH) was examined in ovariectomized (spayed) control, E-treated (28 d), and E+P- treated monkeys (14 d E and 14 d E+P) using in situ hybridization and a 249 bp TPH cRNA probe generated with RT-PCR (n = 5 animals/group). Densitometric analysis of film autoradiographs revealed a ninefold increase in TPH mRNA in E-treated macaques compared to spayed animals (p < 0.05). With supplemental P treatment, TPH mRNA signal was increased fivefold over spayed animals (p < 0.05), but was not significantly different compared to E-treated animals. These results were verified by grain counts from photographic emulsion- coated slides. There were significantly higher single-cell levels of TPH mRNA in serotonergic neurons of the dorsal raphe in E- and E+P-treated groups (p < 0.05). These data indicate that E induces TPH gene expression in nonhuman primates and that the addition of P has little additive effect on TPH gene expression. Thus, the action of P on prolactin secretion is probably not mediated at the level of TPH gene transcription. However, because P increases raphe serotonin content in E-primed rodents, the possibility remains that P may have other actions on post-translational processing or enzyme activity.

Original languageEnglish (US)
Pages (from-to)7021-7029
Number of pages9
JournalJournal of Neuroscience
Issue number21
StatePublished - Nov 1 1996
Externally publishedYes


  • dorsal raphe
  • estrogen
  • monkey
  • progesterone
  • serotonin
  • tryptophan hydroxylase mRNA

ASJC Scopus subject areas

  • Neuroscience(all)


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