Circadian phase alteration by GABA and light differs in diurnal and nocturnal rodents during the day.
These studies investigated the circadian effects of light and gamma aminobutyric acid-A (GABAA) receptor activation in the suprachiasmatic nucleus (SCN) of the diurnal unstriped Nile grass rat (Arvicanthis niloticus). Microinjection of the GABAA agonist muscimol into the SCN during the day produced phase shifts that were opposite in direction to those previously reported in nocturnal rodents. In addition, light had no significant effect on the magnitude of muscimol-induced phase delays during the daytime. Injection of muscimol during the night, however, significantly inhibited light-induced phase delays and advances in a manner similar to that previously reported in nocturnal rodents. Therefore, the circadian effects of GABAA receptor activation are similar in diurnal and nocturnal species during the night but differ significantly during the day.
Novak
Colleen M
CM
Departments of Biology and Psychology, Center for Behavioral Neuroscience, PO Box 4010, Georgia State University, Atlanta, GA 30302-4010, USA. biocmn@langate.gsu.edu
Albers
H Elliott
HE
D000704:Analysis of Variance; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology*; D008027:Light; D008297:Male; D008845:Microinjections / Q000379:methods; D009043:Motor Activity / Q000187:drug effects / Q000528:radiation effects; D009118:Muscimol / Q000494:pharmacology; D010775:Photic Stimulation / Q000379:methods; D051381:Rats; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018755:GABA Agonists; D009118:Muscimol; D005680:gamma-Aminobutyric Acid