Oxytocin mRNA Levels Research Articles

Vasopressin and oxytocin mRNAs in adrenalectomized and Brattleboro rats: analysis by quantitative in situ hybridization histochemistry

35S-labeled synthetic oligodeoxyribonucleotide probes were used to measure levels of vasopressin (VP) and oxytocin (OT) mRNAs in rat hypothalamus by quantitative in situ hybridization histochemistry (ISHH). VP and OT mRNA-containing cells were seen in the paraventricular (PVN) and supraoptic (SON) nuclei. VP mRNA was found to increase five-fold in the parvocellular region of the PVN after adrenalectomy while no changes occurred in magnocellular VP or OT mRNA levels. In the Brattleboro rat, VP mRNA levels were decreased and OT mRNA levels increased in the magnocellular regions. RNA species containing the VP introns were present at one fortieth of the level of processed VP mRNA in control rats. We also performed ISHH followed by immunohistochemistry on the same sections. We found that VP and its encoding mRNA were always located together as were OT-neurophysin and its encoding mRNA. In this study, we extend previous work by showing the characteristic distributions in the PVN and SON of VP and OT mRNA-containing cells and by measuring neuropeptide mRNA changes.

Ovulation triggers oxytocin gene expression in the bovine ovary

The gene for the nonapeptide neurohormone oxytocin is highly expressed in the bovine corpus luteum. Measurements of oxytocin-specific mRNA through the oestrous cycle of non-pregnant cows show that transcription is maximal accompanying ovulation and decreases rapidly thereafter. In contrast, immuno-histochemistry shows neurophysin peptide levels to be greatest at mid-cycle. Low levels of oxytocin mRNA are detected in follicles and in the luteolytic half of the cycle. This mRNA is virtually absent in the corpus luteum of pregnant cattle. No cyclicity is evident in hypothalamic oxytocin mRNA levels. Oxytocin Neurophysin Corpus luteum Estrous cycle Gene expression

Vasopressin gene is expressed at low levels in the hypothalamus of the Brattleboro rat.

The Brattleboro rat carries as a recessive trait the inability to synthesize hypothalamic vasopressin and its related neurophysin but is able to synthesize oxytocin and its neurophysin. Brattleboro rats homozygous for this trait have no immunologically detectable circulating vasopressin and manifest a complete syndrome of diabetes insipidus, which is corrected with vasopressin replacement therapy. Such a defect could be due to absence of the gene encoding vasopressin, the presence of an abnormal gene, or a variety of transcriptional or posttranscriptional abnormalities. We report here that the hypothalamus of the Brattleboro rat contains detectable, although markedly reduced, levels of an mRNA indistinguishable in size with and similar in sequence to authentic vasopressin mRNA. Corresponding levels of oxytocin mRNA were the same in Brattleboro and normal rat hypothalami. These findings indicate that the Brattleboro rat expresses a vasopressin gene, but at a reduced level.