The ontogeny of locomotion in rats: The influence of ambient temperature

Abstract

Rats aged 15 to 19 days showed persistent locomotor activity when observed in a small open field at 22.8°C. Higher ambient temperatures greatly curtailed the pups' walking, however. Contrary to prior analyses, the relatively nonattenuating ambulation of rat pups seems to indicate no state of general arousal. The persistent activity among isolated pups does not appear to be a failure to adapt to a novel environment, nor is there much evidence that this behavior represents exploration. The hyperactive state of rat pups reflects a response to their being deprived of the thermal, olfactory, and tactile cues usually found within the litter.

Prenatal alcohol exposure and offspring hyperactivity: The effects of home-cage shavings and test chamber temperature

“…This effect was especially noticeable in 16-day-old pups; it was less so at 22 days and did not occur in 28-day-old pups. These results are in accord with previous findings (Bronstein et al, 1978;Campbell & Raskin, 1978;Goodrick, 1975). They suggest that the hyperactivity seen in 16-day-old rat pups tested in a novel environment is due in part to thermal stress (Allin & Banks, 1971).…”

“…The present data indicate that 16-day-old pups placed in isolation in a novel environment are considerably more active than 10-, 22-, or 28-day-old pups (Bronstein et al, 1978;Campbell et aI., 1969). Most importantly, prenatal alcohol exposure led to an increase in this isolationinduced activity at 16 and 22 days of age.…”

“…Furthermore, the presence of home-cage shavings in the test chamber may affect the hyperactivity, either abolishing it, if the test period is long (Campbell & Raskin, 1978), or enhancing it, if the test period is short (BuelkeSam, Sullivan, Kimmel, & Nelson, 1984;Pappas, Vickers, Buxton, & Pusztay, 1982). Finally, if the pup is separated from its littermates and placed in an environment at or above 33 0 C (thermoneutrality for the preweanling rat pup), it may not show an increase in activity unless it is isolated for several hours (Bronstein, Marcus, & Hirsch, 1978;Campbell & Raskin, 1978;Goodrick, 1975).…”

Development of locomotor activity of rat pups in figure‐eight mazes

“…since it is unlikely that either starvation (Moorcroft, 1981) or hypothermia (Bronstein, Marcus & Hirsch, 1978) could account for this profile. The lower initial activity on PND 14 for pups tested for only 5 min agrees with data from Experiment I1 indicating that previous testing increased activity on PND 15.…”

“…Therefore, 5 min of testing per day was sufficient for pups to become familiar with the maze so that their activity on PND 15 differed from that of naive animals (Experiment 11). It is interesting that a peak in activity was seen for pups separated from the dam for only 5 min each day, 256 RUPPERT, DEAN, AND REITER since it is unlikely that either starvation (Moorcroft, 1981) or hypothermia (Bronstein, Marcus & Hirsch, 1978) could account for this profile. The lower initial activity on PND 14 for pups tested for only 5 min agrees with data from Experiment I1 indicating that previous testing increased activity on PND 15.…”