Thermoregulatory effects of central injection of noradrenaline in the new-born columbian ground squirrel ( Spermophilus columbianus)

Abstract

1. 1.Effects of centrally injected noradrenaline (NA) into new-born (12–300 h. post-partum) Columbian ground squirrels ( Spermophilus columbianus) were studied to provide comparative data on ontogeny of the thermoregulatory pathways in a hibernating species. 2. 2.At warm ambient temperatures (32–34°C, similar to nest temperature), NA increased heat production (47–92%). rectal temperature (0.27–1.73°C), and axillary temperature (0.59–1.92°C). Peak magnitudes of heat production increased with increasing age on a per unit weight basis. 3. 3.At lower temperatures (28–31°C), NA had no effect on heat production. 4. 4.The data indicate that metabolic and thermal responses to NA in neonates of hibernating species are comparable (e.g. rabbit. guinea pig) or different (e.g. lamb) from those observed in neonates of non-hibernating species.