introduction: the magnocellular neurons (mcns) of the supraoptic nucleus (son) play a crucial role in control of physiological and pathophysiologiccal condition due to two peptides that they synthesize, i.e. oxytocin (oxt) and vasopressin (avp). the activity of mcns is regulated by a variety of excitatory and inhibitory inputs. opioid receptors are one of the important receptors in son synapses...

objective(s): opioids and cannabinoids are two important compounds that have been shown to influence the activity of magnocellular neurons (mcns) of supraoptic nucleus (son). the interaction between opioidergic and cannabinoidergic systems in various structures of the brain and spinal cord is now well established, but not in the mcns of son. materials and methods: in this study, whole cell patc...

The present experiments were undertaken to examine whether oxytocin cells in the supraoptic nucleus receive synaptic inputs from the contralateral supraoptic nucleus or paraventricular nucleus. Using urethane-anesthetized lactating rats, extracellular action potentials were recorded from single oxytocin or vasopressin cells in the supraoptic nucleus. Electrical stimulation was applied to the co...

the 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 an...

We measured stimulation of c-fos and oxytocin gene expression during excitation of oxytocin cells induced by systemic or local morphine withdrawal. Female rats were made morphine-dependent by intracerebroventricular morphine infusion over 5 d. Morphine withdrawal, induced by systemic injection of the opioid antagonist naloxone (5 mg/kg) in conscious or anesthetized rats, increased the density o...

We investigated the influence of endogenous kappa-opioids on the activity of supraoptic neurons in vivo. Administration of the kappa-antagonist nor-binaltorphimine (200 micrograms/kg, i.v.), increased the activity of phasic (vasopressin), but not continuously active (oxytocin), supraoptic neurons by increasing burst duration (by 69 +/- 24%) and decreasing the interburst interval (by 19 +/- 11%)...

Oxytocin secretion is important for the normal progress of parturition in the rat. We tested the hypotheses that contractions of the uterus before pup delivery activate oxytocin neurons, and that they do so via a noradrenergic projection. In anesthetized 22-day (term) pregnant rats, i.v. oxytocin pulses enhanced both uterine contractile activity and the firing rate of oxytocin and vasopressin n...

The peptides alpha-melanocyte stimulating hormone (alpha-MSH) and oxytocin, when administered centrally, produce similar behavioral effects. alpha-MSH induces Fos expression in supraoptic oxytocin neurons, and alpha-MSH melanocortin-4 receptors (MC4Rs) are highly expressed in the supraoptic nucleus, suggesting that alpha-MSH and oxytocin actions are not independent. Here we investigated the eff...

In previous research, we studied both the oxytocin and vasopressin ontogeny in the hypothalamic supraoptic and paraventricular nuclei, and the ANP-ontogeny in the hypothalamic supraoptic nucleus. In this paper we evaluate the ANP-ontogeny in the rat hypothalamic suprachiasmatic nucleus; infact the suprachiasmatic nucleus it is known to synthesize vasopressin, a peptidic hormone involved in the ...