Modulation of light-induced C-Fos expression in the suprachiasmatic nuclei by 5-HT1A receptor agonists.
In previous studies, we showed that light-induced Fos protein expression in the ventrolateral SCN is markedly inhibited by the nonselective serotonergic, quipazine. The present experiments were undertaken to characterize the effects of various serotonin (5-HT) receptor ligands on photic signalling in the SCN. The extent of expression of light-induced Fos-like immunoreactivity (Fos-LI) in the SCN was used as a marker for this response. Exposure of hamsters to a light pulse delivered during the latter part of the dark phase (7 h after lights-off; LD 14:10) elicited an intense expression of Fos-LI in nuclei of cells situated principally in the ventrolateral region of the SCN. Pretreatment with an i.p. injection of the 5-HT1A receptor agonists, 8-OH-DPAT or buspirone, 30 min before the light pulse significantly inhibited the photic expression of Fos-LI (maximal suppression 45.7 +/- 8.1 and 43.0 +/- 1.3%, respectively, both P < 0.01 vs. vehicle controls). Treatment with the 5-HT1A receptor antagonist, NAN-190, administered 15 min before 8-OH-DPAT injection prevented the inhibitory effect of 8-OH-DPAT (100.9 +/- 6.0% vs. controls, P > 0.9). Pretreatment with the 5-HT1B receptor agonist, TFMPP, caused a small but significant suppression of Fos-LI (14.8 +/- 3.5% vs. controls, P < 0.05). In contrast to the significant 5-HT1 receptor agonist effects, pretreatment with 5-HT2 or 5-HT3 receptor agonists, alpha-methyl-5-HT and 1-phenylbiguanide had little suppressive effect on Fos-LI (7.9 +/- 2.1 and 13.0 +/- 5.0% suppression, respectively, both P > 0.1 vs. controls).(ABSTRACT TRUNCATED AT 250 WORDS)
Glass
J D
JD
Department of Biological Sciences, Kent State University, OH 44242.
Selim
M
M
Rea
M A
MA
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D006224:Cricetinae; D003624:Darkness; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D008297:Male; D008647:Mesocricetus; D010879:Piperazines / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D014364:Tryptophan / Q000494:pharmacology
D001645:Biguanides; D010879:Piperazines; D016760:Proto-Oncogene Proteins c-fos; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D014364:Tryptophan; C008846:phenyl biguanide