The Comparison of the Effects of Acute and Repeated Morphine Administration on Fast Synaptic Transmission in Magnocellular Neurons of Supraoptic Nucleus, Plasma Vasopressin Levels, and Urine Volume of Male Rats

AuthorMitra Yousefpouren
AuthorNima Naderien
AuthorZahra Mansourien
AuthorMahyar Janahmadien
AuthorAmir-Mohammad Alizadehen
AuthorFereshteh Motamedien
Issued Date2014-07-31en
AbstractThe activity of the magnocellular neurons (MCNs) of supraoptic nucleus (SON) is regulated by a variety of excitatory and inhibitory inputs. Opioids are one of the important compounds that affect these inputs at SON synapses. In this study, whole-cell patch clamp recording of SON neurons was used to investigate the effect of acute and repeated morphine administration on spontaneous inhibitory and excitatory post synaptic currents (sIPSCs and sEPSCs) in MCNs. While acute bath application of morphine to brain slice of intact rat produced an increase in sEPSCs frequency and a decrease in sIPSCs frequency, repeated in-vivo administration of morphine produced opposite effect. Moreover, repetitive i.c.v. administration of morphine for three consecutive days caused significant increase in urine volume, but had no significant alteration in water consumption compared to control group. The increase in urine volume was consistent with a significant decrease in plasma arginine vasopressin (AVP) levels after repetitive i.p. morphine administration. The results suggest that acute administration of morphine stimulates whereas repeated administration of morphine inhibits the MCNs. Morphine-induced MCN inhibition could result in diminished plasma AVP levels and eventually an increase in urine volume of rats.en
DOIhttps://doi.org/10.22037/ijpr.2014.1549en
KeywordSupraoptic nucleusen
KeywordMorphineen
KeywordArginine vasopressinen
KeywordUrine volumeen
KeywordsIPSCen
KeywordsEPSCen
PublisherBrieflandsen
TitleThe Comparison of the Effects of Acute and Repeated Morphine Administration on Fast Synaptic Transmission in Magnocellular Neurons of Supraoptic Nucleus, Plasma Vasopressin Levels, and Urine Volume of Male Ratsen
TypeOriginal Articleen

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