Role of prolactin and the gonads in seasonal physiological changes in the collared lemming (Dicrostonyx groenlandicus).
On a seasonal basis, collared lemmings undergo a number of physiological and morphological changes. Short photoperiod exposure results in a molt to a white pelage, an increase in body weight, a reduction in relative body fat content, an increase in relative water content, and the development of a bifid claw. Treatment with the dopamine agonist, CB-154, resulted in a reduction in serum prolactin and the development of the white pelage in lemmings housed under 16L:8D, while treatment with the dopamine antagonist, sulpiride, prevented the winter molt in animals transferred to 8L:16D. Castration under 16L:8D resulted in an increase in body weight and an enlargement of the bifid claw. Castrated animals also molted more readily when treated with CB-154 and developed a relatively greater carcass water content. Treatment with CB-154 increased relative carcass fat content. These findings suggest that, in the collared lemming, seasonal changes in pelage parameters are regulated by prolactin, with gonadal hormones playing a modulating role. Body weight, water content, and bifid claw size appear to be influenced by gonadal hormones.
School of Life and Health Sciences, University of Delaware, Newark 19716.
B A
BA
Gower
T R
TR
Nagy
M H
MH
Stetson
D000818:Animals; D003411:Arvicolinae; D001971:Bromocriptine / Q000494:pharmacology; D005260:Female; D008297:Male; D011388:Prolactin / Q000502:physiology*; D012621:Seasons; D013469:Sulpiride / Q000494:pharmacology; D013737:Testis / Q000502:physiology*
D001971:Bromocriptine; D013469:Sulpiride; D011388:Prolactin