Effects of warmth on newborn rats' motor activity and oral responsiveness to an artificial nipple.

Abstract

Temperature is a powerful regulator of the behavior and physiology of newborn altricial animals. The effects of warmth on newborn rats' oral responsiveness to suckling stimuli and spontaneous motor activity in a thermoneutral environment were investigated. Newborn rat pups' oral grasp responses to an artificial nipple and overall motor activity were recorded for 18 min. Near-term pups were delivered by cesarean section so that their 1st experiences with suckling stimuli could be observed. Experimental pups were warmed for 15 s every 2 min; control pups were not warmed. Warmed pups grasped the nipple fewer times than the not-warmed pups. However, oral grasp durations became longer for the warmed pups but not for the not-warmed pups. Warmth increased pups' motor activity but only while the heat was applied. Warmth in a thermoneutral environment may promote longer nipple attachment during newborns' early feeding experiences.

Air-stepping in neonatal rats: A comparison of L-dopa injection and olfactory stimulation.

“…Compared with previous studies (Fady et al, 1998), there was a lower rate in olfactory-induced air-stepping. The lower ambient temperature in the experimental conditions may be the reason for the difference in levels of activity among the experiments (Bacher, Smotherman, & Robertson, 2001; Gordon, 1990). In the present study, the rats were filmed under a UV lamp that did not diffuse heat, whereas in the previous experiments, spotlights lit the site, maintaining a high ambient temperature for the rat.…”