The induction of low nocturnal secretion of melatonin caused by reverse feeding rhythms depends on availability of macronutrient diets.
The present study investigated the effect of single chow diet and two-way dietary choice between a protein-rich and a carbohydrate-rich diet ingested during free access or daytime access (08.00-16.00 h) on the rhythms of ingestion and on nocturnal levels of serum melatonin and pineal N-acetyltransferase activity in rats. Animals with free access to the single or the choice diets displayed a circadian rhythmicity of total food intake with peaks at the beginning, the middle and the end of the dark phase. Rats fed the dietary choice displayed a preference for carbohydrate at the beginning, and a preference for protein at the middle and the end of the dark phase. Under daytime feeding access, both dietary conditions resulted in only one peak of total intake at the beginning of the access period. Rats fed the choice diets on the daytime feeding schedule initially preferred carbohydrate to protein but this preference disappeared subsequently. Nocturnal peaks of serum melatonin and pineal NAT activity were lower with daytime access to dietary choice compared to ad libitum access. The results suggest that in a two-way selection of macronutrients, feeding cycle can directly act on the rhythms expressed within the pineal gland.
Selmaoui
B
B
Laboratoire de chronobiologie, Hôpital du Sacré-Coeur de Montreal, 5400 Boulevard Gouin Ouest, Montréal, Que., Canada H4J 1C5.
Thibault
L
L
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D001835:Body Weight; D002940:Circadian Rhythm; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating; D005502:Food; D008297:Male; D008550:Melatonin / Q000097:blood / Q000378:metabolism*; D010870:Pineal Gland / Q000201:enzymology; D051381:Rats
D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin