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Involvement of 5-HT1A receptor mechanisms in the inhibitory effects of methamphetamine on photic responses in the rodent suprachiasmatic nucleus |
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| Authors: | Takahiro Moriya Shiro Yamanouchi Tatsuto Fukushima Takao Shimazoe Shigenobu Shibata Shigenori Watanabe |
| Affiliation: | aDepartmeat of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University 62, Fukuoka 812-82, Japan bDepartment of Pharmacology, School of Human Sciences, Waseda University, Tokorozawa 359, Japan |
| Abstract: | We examined the role of serotonin 1A (5-HT1A) receptors in the inhibitory effects of methamphetamine (MA) on photic entrainment to the circadian pacemaker in the suprachiasmatic nucleus (SCN) of rodents. MA inhibited optic nerve stimulation-evoked field potential in the SCN, light-induced Fos expression in the SCN and light-induced phase shift of hamster wheel-running rhythm. NAN-190, a 5-HT1A receptor antagonist, eliminated the inhibitory effects of MA. NAN-190 has also been reported to antagonize 1 adrenergic receptors. However, prazosin, which selectively antagonizes 1 adrenergic receptors, did not affect the inhibitory action of MA on light-induced Fos expression. In addition, parachloroamphetamine, which is known to be a 5-HT releaser, dose-dependently inhibited light-induced phase shift of wheel-running rhythm. These findings suggest that elevation of endogenous 5-HT levels by MA inhibits the photic entraining responses of the circadian pacemaker in the SCN via 5-HT1A receptor stimulation of the 5-HT released by MA. |
| Keywords: | Circadian rhythm Suprachiasmatic nucleus Methamphetamine NAN-190 5-HT 1A receptor Serotonin |
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