Serotonin in the raphe nuclei: regulation by light and an endogenous pacemaker.
Temporal changes of serotonin (5-HT) content in the median (MRN) and dorsal (DRN) raphe nuclei were measured in rats kept under various lighting conditions. Serotonin content in the MRN and DRN under light-dark (LD) condition showed diurnal rhythmicity, with a peak during early light phase and a trough during the dark phase. In constant dark (DD) condition, a single peak was observed and was out of phase to the 5-HT peak found under LD condition. Animals exposed to constant light (LL) after 2 days in DD showed marked increase in 5-HT after lights on. These results suggest that changes in 5-HT in the MRN and DRN are regulated by an endogenous pacemaker and by light.
Cagampang
F R
FR
Laboratory of Integrative Brain Function, Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
Yamazaki
S
S
Otori
Y
Y
Inouye
S I
SI
D000704:Analysis of Variance; D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D008027:Light; D008297:Male; D011903:Raphe Nuclei / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin