CCK-8 excites oxytocin-secreting neurons in the paraventricular nucleus in rats—Possible involvement of noradrenergic pathway
Systemic administration of CCK-8 increased plasma oxytocin (OXT) level in rats anesthetized with a mixture of urethane and α-chloralose. Extracellular recordings were made from magnocellular neurosecretory neurons in the paraventricular nucleus (PVN) of the hypothalamus in anesthetized rats to exami...
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Veröffentlicht in: | Brain research bulletin 1993, Vol.32 (5), p.453-459 |
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Zusammenfassung: | Systemic administration of CCK-8 increased plasma oxytocin (OXT) level in rats anesthetized with a mixture of urethane and α-chloralose. Extracellular recordings were made from magnocellular neurosecretory neurons in the paraventricular nucleus (PVN) of the hypothalamus in anesthetized rats to examine the effects of CCK-8 on the firing of PVN neurons. Thirteen out of 16 nonphasic neurons (putative OXT-secreting neurons) were excited by intravenous and/or intraperitoneal administration of CCK-8. By contrast, 8 out of 10 phasic cells, vasopressin(AVP)-secreting cells, were inhibited by systemic administration of CCK-8. Four out of five nonneurosecretory neurons in the PVN were excited by the administration of CCK-8. Moreover, microiontophoretically applied phentolamine blocked the excitatory responses induced by CCK-8 in nonphasic neurons. We measured extracellular noradrenaline (NA) level in the PVN, using in vivo microdialysis. Intravenous administration of CCK-8 induced NA release in the PVN. These results suggest that CCK-8 activates the excitatory afferent pathway to putative OXT-secreting neurons in the PVN which may, at least in part, be involved in the central noradrenergic projection. |
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ISSN: | 0361-9230 1873-2747 |
DOI: | 10.1016/0361-9230(93)90290-R |