Ovarian steroid regulation of tryptophan hydroxylase mRNA expression in rhesus macaques.
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.
Pecins-Thompson
M
M
Division of Reproductive Sciences, Oregon Regional Primate Research Center, Beaverton, Oregon 97006, USA.
Brown
N A
NA
Kohama
S G
SG
Bethea
C L
CL
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004967:Estrogens / Q000097:blood / Q000502:physiology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D017403:In Situ Hybridization; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D018377:Neurotransmitter Agents / Q000378:metabolism; D010052:Ovariectomy; D010053:Ovary / Q000201:enzymology* / Q000502:physiology; D011374:Progesterone / Q000097:blood / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D011903:Raphe Nuclei / Q000502:physiology; D012701:Serotonin / Q000096:biosynthesis / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology; D014365:Tryptophan Hydroxylase / Q000235:genetics*
D018076:DNA, Complementary; D004967:Estrogens; D018377:Neurotransmitter Agents; D012333:RNA, Messenger; D012701:Serotonin; D011374:Progesterone; D014365:Tryptophan Hydroxylase