Abstract
Peripheral administration of cholecystokinin (CCK)-8 selectively activates oxytocin (OXT)-secreting neurons in the supraoptic (SON) and the paraventricular nuclei (PVN) with the elevation of plasma OXT level in rats. We examined the effects of intravenous (iv) administration of CCK-8 on the neuronal activity of hypothalamic OXT-secreting neurons and plasma OXT level in Otsuka Long-Evans Tokushima Fatty (OLETF) rats that have a congenital defect in the expression of the CCK-A receptor gene. In situ hybridization histochemistry (ISH) for c-fos mRNA revealed that the expression of the c-fos gene was not induced in the SON, the PVN, the nucleus of the tractus solitarius (NTS) and the area postrema (AP) 30 min after iv administration of CCK-8 (20 and 40 μg/kg) in OLETF rats. In Long-Evans Tokushima Otsuka (LETO) rats (controls), c-fos mRNA was detected abundantly in those nuclei 30 min after iv administration of CCK-8 (20 μg/kg). Immunohistochemistry for c-fos protein (Fos) showed that the distributions of Fos-like immunoreactivity (LI) were identical to the results obtained from ISH. Dual immunostaining for OXT and Fos revealed that Fos-LI was mainly observed in OXT-secreting neurons in the SON and the PVN of LETO rats 90 min after iv administration of CCK-8 (20 μg/kg). Radioimmunoassay for OXT and arginine vasopressin (AVP) showed that iv administration of CCK-8 did not cause significant change in the plasma OXT and AVP levels in OLETF rats, while iv administration of CCK-8 caused a significant elevation of plasma OXT level without changing the plasma AVP level in LETO rats. These results suggest that peripheral administration of CCK-8 may selectively activate the hypothalamic OXT-secreting neurons and brainstem neurons through CCK-A receptor in rats.
Original language | English |
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Pages (from-to) | 16-25 |
Number of pages | 10 |
Journal | Autonomic Neuroscience: Basic and Clinical |
Volume | 121 |
Issue number | 1-2 |
DOIs | |
State | Published - Aug 31 2005 |
Bibliographical note
Funding Information:This study was supported by Grant-in-Aid for Scientific Research (B) No. 16390061 from the Ministry of Education, Culture, Sports, Science and Technology and a grant from Ajinomoto Co. Ltd (Japan).
Keywords
- CCK-A receptor
- Otsuka Long-Evans Tokushima Fatty rat
- Oxytocin
- Paraventricular nucleus
- Supraoptic nucleus
ASJC Scopus subject areas
- Endocrine and Autonomic Systems
- Clinical Neurology
- Cellular and Molecular Neuroscience