| Abstract: | Assessed the role of seasonal hyperphagia in the genesis of prehibernation fattening 19 female golden-mantled ground squirrels (Spermophilus lateralis). Control Ss (n?=?17) were fed ad lib throughout the weight gain phase of the annual bodyweight cycle (June–October), and neurologically intact Ss (n?=?7) and Ss with brain lesions incorporating the suprachiasmatic nuclei (SCN; n?=?5) were fed amounts of food equivalent to quantities consumed prior to the bodyweight trough (May). Results indicate that part of the seasonal increase of body mass was independent of increases in food consumption; intact Ss and controls underwent similar increases in body mass and possessed equivalent amounts of abdominal white adipose tissue. Food restriction combined with SCN lesions attenuated seasonal weight gain and reduced abdominal fat mass. However, some brain-damaged Ss still evidenced weight gain. It is concluded that SCN are involved in circannual body weight rhythm generation, but their contribution to this process is not essential for continued rhythmicity in most individuals. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
