Survival and Development of Maternally Deprived Rats: Role of Body Temperature

Abstract

Rat pups, 10-12 days old, survived maternal deprivation if kept warm at 35 degrees, but died within 6 days if allowed to become hypothermic at a room temperature of 23 degrees. Normal body temperatures facilitated feeding, but even without food, warm pups survived starvation longer than cool ones. Increased survival could not be attributed to decreased oxygen consumption, and warm pups lost more body water and solids than cool pups. Striking differences in development that may have affected survival were observed over 72 hr of separation without food. Cool pups showed a virtual arrest of the growth of the tail, fur, tibia, and femur, and failed to increase brain weight, protein, DNA, RNA, and catecholamine contents. Warm pups showed developmental growth more comparable to that of normally mothered pups and significantly exceeded controls in the rate of accumulation of brain norepinephrine and dopamine.

Periodic maternal separation of neonatal rats produces region- and gender-specific effects on biogenic amine content in postmortem adult brain

“…Repeated isolation between PND 2-15 in a cool environment (20°C) resulted in a mesolimbic/ mesostriatal dopaminergic functional hypersensitivity, whereas isolation in a warmer environment (34°C, nest temperature), resulted in a dopaminergic functional hyposensitivity. Also, Stone et al (1976) reported that 10 -12-day-old pups, separated from their dams at nest temperatures for 72 h, showed a significant increase in postmortem brain tissue levels of noradrenaline and dopamine compared with nonseparated controls. Although these changes were regionally nonspecific, the observation that separation in a warm environment leads to an overall increase in brain dopamine levels is obviously compatible with the data from the current experiment.…”

Effect of Amphetamine on the Metabolism and Incorporation of [³H]-Thymidine into DNA of Developing Rat Brain

“…Based on reports in the literature [10, 17,22,23,29,34,36] it is possible that at our higher amphetamine doses (owing to the quicker utilization) the energy reserves run short at least in certain areas of the brain. Since ATP is needed for the incorporation of thymidine triphosphate into the DNA, the estimation of high energy phosphate levels seems to be warranted.…”

Hidden Regulators Within the Mother–Infant Interaction

“…As separation took place, each of the individual behavioral and physiological systems of the infant rat responded to the loss of one or another of the components of the infants' previous interaction with its mother. Providing one of these components to a separated pup, for example maternal warmth, maintained the level of brain biogenic amine function underlying the pups' general activity level (Stone, Bonnet, & Hofer, 1976;Hofer, 1980) but had no effect on other systems, for example, the pups' cardiac rate continued to fall regardless of whether supplemental heat was provided (Hofer, 1971). The heart rate, normally maintained by sympathetic autonomic tone, we found was regulated by provision of milk to neural receptors in the lining of the pup's stomach (Hofer & Weiner, 1975).…”