Effects of individual housing on circadian rhythms of adult rats.
Circadian rhythms of hypothalamic serotonin (5HT), its precursor tryptophan (TP) and its metabolite 5-hydroxy-indoleacetic acid (5HIAA), and of prolactin and corticosterone circulating hormones were determined in group-housed and in individually-housed male rats, adapted to a 12:12 light/dark cycle. After 5 weeks of individual housing, 5HT peaked later, TP and 5HIAA peaked earlier, and the mesor level of TP and 5HIAA decreased with respect to group-housed animals. Individual housing caused an increase in the corticosterone mesor level, but did not affect amplitude or acrophase. The circadian rhythm of prolactin was unchanged by individual housing.
Greco
A M
AM
Istituto di Scienze Fisiologiche Umane, II Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli, Italy.
Gambardella
P
P
Sticchi
R
R
D'Aponte
D
D
Di Renzo
G
G
De Franciscis
P
P
D000818:Animals; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood*; D006799:Housing, Animal; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D007031:Hypothalamus / Q000032:analysis* / Q000378:metabolism; D008297:Male; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis* / Q000378:metabolism; D012934:Social Isolation; D014364:Tryptophan / Q000032:analysis
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D011388:Prolactin; D003345:Corticosterone