R. Aguilarroblero et al., ORGANIZATION OF CIRCADIAN RHYTHMICITY AND SUPRACHIASMATIC NUCLEI IN MALNOURISHED RATS, American journal of physiology. Regulatory, integrative and comparative physiology, 42(4), 1997, pp. 1321-1331
The present study was aimed at characterizing the effects of low-prote
in malnutrition (6% casein) on the circadian rhythm of drinking behavi
or and on suprachiasmatic nuclei immunohistochemistry in Sprague-Dawle
y rats. Recordings were started at 30 days of age under a 12:12-h ligh
t-dark (LD) cycle. At age 150 days, recordings were continued under co
nstant dim red light, and finally the latency to entrain to complete a
nd skeleton photoperiods was established. At the end of the recordings
rats were processed for histological analysis. Compared with their co
ntrols, malnournished rats exhibited 1) splitting of rhythmicity under
LD that 2) condensed to one component in constant dim red light, 3) d
elayed entrainment to skeleton photoperiod, and 4) precocious entrainm
ent under complete photoperiod. Immunohistochemical analysis showed ma
inly a decrease in the immunohistochemical detection of vasoactive int
estinal polypeptide and glial fibrillar acid protein cells in malnouri
shed animals. These results indicate that in malnourished rats there i
s a decrease 1) in the coupling force among the oscillators and 2) in
the strength of the phase lock between the oscillators and the light-d
ark cycle.