Phase advances of circadian rhythms in somatostatin depleted rats: effects of cysteamine on rhythms of locomotor activity and electrical discharge of the suprachiasmatic nucleus |
| |
Authors: | C Fukuhara S -I T Inouye K Aoki T Hamada S Shibata S Watanabe |
| |
Institution: | (1) Laboratory of Integrative Brain Functions, Mitsubishi Kasei Institute of Life Sciences, 11, Minami-Ooya, Machida, 194 Tokyo, Japan;(2) Life Science Institute, Sophia University, 7-1 Kioicho, Chiyoda-ku, 102 Tokyo, Japan;(3) Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University, 812 Fukuoka, Japan |
| |
Abstract: | Somatostatin is synthesized in the suprachiasmatic nucleus (SCN), a circadian pacemaker in mammals. To explore the functional significance of somatostatin in the circadian system, we examined rhythms of rat locomotor activity and electrical firing rate of SCN neurons in the brain slice after temporal depletion of somatostatin levels in the SCN. Intraperitoneal administration of cysteamine (200 mg/kg), a somatostatin depletor, significantly reduced somatostatin level in the in vivo SCN 5 min after injection and kept low level as long as 3 to 4 days. This administration, on the other hand, induced significant phase advances of about 51 min in the subsequent free-running rhythm of locomotor activity of the rat. A marked phase advance in the circadian rhythm of firing rate in the SCN was also observed after administration of cysteamine in coronal hypothalamic slices. These persistent phase shifts after administration of a somatostatin depletor may suggest that the change of somatostatin level in the SCN have a feedback influence on the circadian pacemaker.Abbreviations
SCN
suprachiasmatic nucleus
-
AVP
arginine-vasopressin
-
VIP
vasoactive intestinal polypeptide
-
CT
circadian time
-
ZT
zeitgeber time
-
i.p.
intraperitoneally
-
12L:12D
12 h light and 12 h dark
-
ANOVA
analysis of variance |
| |
Keywords: | Circadian rhythm Suprachiasmatic nucleus Cysteamine Somatostatin Brain slice |
本文献已被 SpringerLink 等数据库收录! |
|