No abstract

Proper maternal behavior is essential for the survival and well-being of offspring. Previous animal research on reduced maternal care has shown that prolonged maternal separation (3-24 h) during the neonatal period can result in a variety of negative outcomes (Aisa et al.,

Rats were adapted to cold by 10-min exposure to −20 °C every hour during daytime for a total of 27 exposures over a period of 3 days. The significant delayed hypothermia observed in these adapted animals when exposed to severe cold (−16 °C) for 4 h was concomitant with only a 15% increase in oxygen consumption over control animals. While some protection against severe cold was observed in rats given 27 injections of 1 μg thyroxine over a 3-day period, the same treatment with 30 μg noradrenaline (NA)/100 g body weight had opposite effects. Urinary NA was increased during the second and third day of adaptation and the excretion during the 4-h test at −16 °C was significantly greater in the adapted than in the control group. No significant changes in adrenaline (A) excretion were observed during the adaptation period. However during the 4-h test at −16 °C, A excretion was four times greater in the control than in the adapted animals. These results could indicate emotional adjustments in animals adapted by intermittent exposures to severe cold (IS adaptation). It might be suggested that adaptation by continuous exposure to moderate cold (CM adaptation) and IS adaptation are both related to catecholamine secretion: in the case of CM adaptation an increased sensitivity to NA would prevail, whereas in IS adaptation a decreased A secretion could be a factor of some importance.