Persistence of circannual rhythms in ground squirrels with lesions of the suprachiasmatic nuclei.
Golden-mantled ground squirrels (Spermophilus lateralis) sustained complete ablation of the suprachiasmatic nuclei (SCN) while being maintained under constant conditions of photoperiod, temperature and food availability. After SCN ablation, most squirrels observed for up to 3 years postsurgically underwent normal circannual cycles in body mass. Other squirrels with similar SCN damage evidenced various anomalies in their circannual body weight cycles. Response of squirrels to SCN ablation was not related to the phase of the annual cycle in which lesions were produced. The variable nature of the effect of SCN ablation on circannual body mass cycles suggests that the SCN are non-essential components of the system underlying the generation or expression of circannual rhythms.
D000818:Animals; D001835:Body Weight; D001931:Brain Mapping; D002940:Circadian Rhythm; D005260:Female; D010507:Periodicity; D012589:Sciuridae / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000502:physiology*