Communicación oral:Is there anybody out there? NO communication in the circadian clock

PLANO SA; AGOSTINO PV; GOLOMBEK DA

Buenos Aires

Congreso; XXII Congreso de Ciencias Fisiologicas; 2006

Light reaches the suprachiasmatic nucleus (SCN) through the retinohypothalamic tract. In mammals, the administration of a light pulse during the late subjetive night induces phase advances in the activity rhythm and activates the immediate early gene cfos. The ventral subdivision of the SCN receives the glutamatergic signal, and transmits it through the dorsal area. Nitric oxide (NO) is a gaseous messenger that might be involved in the intercellular communication within the SCN. In this work we studied the role of NO in the intercellular communication within the ventral and dorsal portions of the SCN. We analyzed wheel-running activity of hamsters receiving a light pulse (7 min, 600 lux) at CT 18 with or without the previous i.c.v. administration of the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). Our results indicate that PTIO injection blocked light-induced phase advances. We also observed a complete inhibition of light induced cFOS-ir in animals treated with PTIO Preliminary results at CT 14 (early subjetive night), when a light pulse induces a phase delay, showed no significant changes in behavioral rhythms of animals treated with PTIO. Thus, the communication within the SCN at CT 14 might be NO-independent. Together, these results suggest that NO may act as an intercellular messenger in the SCN, mediating light-induced phase advances but not phase delays.