DECREASED LEVEL OF LIGHT-INDUCED FOS EXPRESSION IN THE SUPRACHIASMATIC NUCLEUS OF DIABETIC RATS

We assessed light-induced Fos-immunoreactive cells in the suprachiasma tic nucleus of diabetic rats. The number of Fos-immunoreactive cells s ignificantly decreased in diabetic Otsuka Long-Evans Tokushima Fatty ( OLETF) rats as compared with control Long-Evans Tokushima Otsuka (LETO ) rats. In contrast there was no decrease in the number of Fos-immunor eactive cells in young OLETF rats which have not yet developed diabete s. Two months after the administration of streptozotocin (STZ) to Wist ar rats, the number of Fos-immunoreactive cells significantly decrease d, although 1 week after the administration of STZ, the number had not yet changed in these STZ-induced diabetic rats. These results suggest that chronic diabetic (hyperglycemic) conditions may affect the light entraining responses in the suprachiasmatic nucleus (SCN). (C) 1997 E lsevier Science Ireland Ltd.