Chronic exposure to short photoperiod inhibits free thyroxine index and plasma levels of TSH, T4, triiodothyronine (T3) and cholesterol in female Syrian hamsters.
1. Chronic exposure of female Syrian hamsters (Mesocricetus auratus) for 9 weeks to a short photoperiod (10L:14D) depressed the pituitary-thyroid axis as indicated by a drop in circulating titers of thyroid stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3) and the free thyroxine index (FT4I) compared to animals maintained under long photoperiodic conditions (14L:10D). 2. Short day treatment also reduced plasma cholesterol levels. 3. Neither plasma triglycerides, glucose nor growth hormone (GH) levels differed between hamsters exposed to short or long daily photoperiods.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D006224:Cricetinae / Q000502:physiology*; D005260:Female; D008027:Light; D008647:Mesocricetus / Q000502:physiology*; D009929:Organ Size / Q000528:radiation effects; D010053:Ovary / Q000528:radiation effects; D010903:Pituitary Gland, Anterior / Q000528:radiation effects; D011863:Radioimmunoassay; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014280:Triglycerides / Q000097:blood; D014284:Triiodothyronine / Q000097:blood*; D014599:Uterus / Q000528:radiation effects
D001786:Blood Glucose; D014280:Triglycerides; D014284:Triiodothyronine; D013972:Thyrotropin; D002784:Cholesterol; D013974:Thyroxine