Luteinizing hormone-releasing hormone (LHRH) neurons maintained in hypothalamic slice explant cultures exhibit a rapid LHRH mRNA turnover rate.
Evidence indicates that neuropeptide gene expression is tightly coupled to biosynthesis and secretion. Moreover, rhythmic gene expression often accompanies rhythmic secretion. Luteinizing hormone-releasing hormone (LHRH) neurosecretion, which regulates gonadal function, is pulsatile, with interpulse intervals of approximately 1 hr and pulse decays of <30 min in rats. As a basis for a rapid fall in peptide secretion, we hypothesize that LHRH mRNA levels rapidly decay. To address this hypothesis, we examined LHRH mRNA turnover in primary postnatal LHRH neurons maintained in long-term hypothalamic/preoptic area slice explant cultures, using in situ hybridization histochemistry (ISHH). Relative LHRH mRNA content per cell was quantitated by single-cell analysis after transcription inhibition with 5, 6-dichloro-1-D-ribofuranosyl-benzimidazole (DRB) or actinomycin D. Cultures were maintained in serum-free medium with tetrodotoxin to suppress spontaneous electrical activity and hence assess only intrinsic cellular activity. A plot of LHRH mRNA level per cell versus DRB treatment time showed a rapid initial decay of LHRH mRNA (t1/2, 5-13 min), followed by a slower decay rate (t1/2, 329-344 hr). LHRH cell number after drug treatment as determined by immunocytochemistry did not change. Comparison of mammalian LHRH mRNA 3'-untranslated regions showed two conserved regions. These data indicate that, in primary LHRH neurons, LHRH mRNA has an intrinsically high rate of turnover and a mRNA stabilization component. Foremost, decay of LHRH mRNA, the fastest reported for a neuropeptide to date, corresponds to the decay of LHRH peptide pulses.
Maurer
J A
JA
Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
Wray
S
S
D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D004004:Dichlororibofuranosylbenzimidazole; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis / Q000235:genetics*; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors; D011301:Preoptic Area / Q000166:cytology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats
D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D004004:Dichlororibofuranosylbenzimidazole