Sa. Ferguson et Dj. Kennaway, Emergence of altered circadian timing in a cholinergically supersensitive rat line, AM J P-REG, 277(4), 1999, pp. R1171-R1178
Citations number
33
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
Mammalian circadian rhythms are controlled by the suprachiasmatic nuclei (S
CN) in concert with light information. Several neurotransmitters and neural
pathways modulate light effects on SCN timing. This study used a line of r
at with an upregulated cholinergic system to investigate the role of acetyl
choline in rhythmicity. With the use of a selective breeding program based
on the thermic response to a cholinergic agonist, we developed a supersensi
tive (S-ox) and subsensitive (R-ox) rat line. The S-ox rats showed an earli
er onset time of melatonin rhythm under a 12:12-h light-dark photoperiod fr
om generation 3 (3 +/- 0.5 h after dark) compared with R-ox rats (4.5 +/- 0
.1 h) and an earlier morning decline in temperature (0.9 +/- 0.3 h before l
ights on) compared with R-ox animals (0.1 +/- 0.1 h). Furthermore, the S-ox
animals displayed a significantly shorter free-running period of temperatu
re rhythm than R-ox rats (23.9 +/- 0.04 and 24.3 +/- 0.1 h, respectively, P
< 0.05). The results suggest that the altered circadian timing of the S-ox
rats may be related to the cholinergic supersensitivity, intimating a role
for acetylcholine in the circadian timing system.