Involvement of 5-HT1A receptor mechanisms in the inhibitory effects of methamphetamine on photic responses in the rodent suprachiasmatic nucleus.
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 alpha 1 adrenergic receptors. However, prazosin, which selectively antagonizes alpha 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.
Moriya
T
T
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Yamanouchi
S
S
Fukushima
T
T
Shimazoe
T
T
Shibata
S
S
Watanabe
S
S
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D006224:Cricetinae; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D009900:Optic Nerve / Q000502:physiology*; D010775:Photic Stimulation; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects*
D016760:Proto-Oncogene Proteins c-fos; D011985:Receptors, Serotonin; D008694:Methamphetamine