Accession Number:

ADA379555

Title:

Neurophysiological and Behavioural Analysis of Circadian Rhythm Entrainment

Descriptive Note:

Final rept. 1 Feb 1996-30 Jun 1999

Corporate Author:

DALHOUSIE UNIV HALIFAX (NOVA SCOTIA)

Personal Author(s):

• Rusak, Benjamin

Report Date:

2000-03-29

Pagination or Media Count:

13.0

Abstract:

We investigated neurotransmitters which play a role in conveying light information to the circadian clock in the suprachiasmatic nucleus SON. We studied the effects on SON cell responses to light of classic small-molecule transmitters, such as glutamate, serotonin and acetylcholine, as well as a number of peptides. We showed that glutamate can affect SON cell firing rates through both ionotropic and metabotroplc receptors. We found that the peptides GRP and VIP also affect SON in vivo with a pattern of temporal sensitivity similar to that of light. We studied how serotonin and melatonin alter photic responses of SON cells, and showed that serotonin acts via a receptor that resembles the 5-HT7 subtype. We recently demonstrated differences in the responses to light of SON neurons in nocturnal rodents compared to those is degus, a diurnalcrepuscular rodent. In vivo and in vitro studies suggest the possibility that the inhibitory neurotransmitter GABA is found in the retinal entrainment route in both types of mammals, along with the excitatory transmitter glutamate. To facilitate our behavioral studies, we developed a data analysis system for dealing with activity rhythm data collected by computer.

Descriptors:

• *CIRCADIAN RHYTHMS
• *BIOLOGICAL RHYTHMS
• GLUTAMIC ACID
• LIGHT
• NOVA SCOTIA
• NERVE CELLS
• SEROTONIN
• NEUROTRANSMITTERS
• ENTRAINMENT
• NEUROPHYSIOLOGY
• ACETYLCHOLINE
• MELATONIN

Subject Categories:

• Anatomy and Physiology
• Medicine and Medical Research

Distribution Statement:

APPROVED FOR PUBLIC RELEASE