PMID:18088359

Citation	Yue, C, Mutsuga, N, Sugimura, Y, Verbalis, J and Gainer, H (2008) Differential kinetics of oxytocin and vasopressin heteronuclear RNA expression in the rat supraoptic nucleus in response to chronic salt loading in vivo. J. Neuroendocrinol. 20:227-32
Abstract	Previous studies have shown that the secretion of oxytocin and vasopressin from the posterior pituitary always accompanies systemic hyperosmotic stimuli in rats, and that oxytocin and vasopressin mRNAs consistently increase in response to prolonged hyperosmotic stimuli. Hence, it has been widely interpreted that oxytocin and vasopressin secretion and gene expression are closely coupled. In the present study, we used both vasopressin and oxytocin intron- specific probes to measure vasopressin and oxytocin heteronuclear RNA (hnRNA) levels, respectively, by in situ hybridisation in the rat supraoptic nucleus (SON) in conjunction with radioimmunoassays of vasopressin and oxytocin peptide levels in plasma and in the posterior pituitary in normally hydrated rats and after 1-5 days of salt loading. Increased oxytocin secretion in response to hyperosmotic stimuli exceeded vasopressin secretion at every time point studied. Vasopressin hnRNA in the SON increased to near maximal levels within minutes after the hyperosmotic stimulus, and was maintained throughout all 5 days of salt loading. By contrast, oxytocin hnRNA did not significantly change from control levels until approximately 2 days after hyperosmotic stimulation, and was not maximal until 3 days. In summary, increases in oxytocin gene transcription in response to osmotic stimuli are dramatically delayed compared to increases in vasopressin gene transcription under the same conditions. These data indicate that oxytocin gene transcription is not as closely correlated with pituitary peptide secretion as is vasopressin gene transcription, and suggests that there is a fundamental difference in excitation-secretion-transcription coupling mechanisms that regulate these two closely related genes in the rat magnocellular neurones in the SON.
Links	PubMed Online version:10.1111/j.1365-2826.2007.01640.x
Keywords	Animals; Blood; Drug Administration Schedule; Gene Expression/drug effects; In Situ Hybridization; Kinetics; Male; Osmolar Concentration; Oxytocin/genetics; Pituitary Gland, Posterior/drug effects; Pituitary Gland, Posterior/metabolism; RNA, Heterogeneous Nuclear/metabolism; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Sodium Chloride/administration & dosage; Sodium Chloride/pharmacology; Supraoptic Nucleus/drug effects; Supraoptic Nucleus/metabolism; Time Factors; Vasopressins/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RAT:NEU1	involved_in	GO:0042538: hyperosmotic salinity response	ECO:0000270: expression pattern evidence used in manual assertion		P		Seeded From UniProt	complete

References

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