Endocrine responses to mother‐infant separation in developing rats

Abstract

Separation of neonatal rat pups from the dam have been reported to elicit two endocrine responses in the pup: a fall in growth hormone secretion and a rise in corticosterone secretion. However, the temporal, ontogenetic, and behavioral determinants of these responses have not been compared. In the present study, we report that these two responses can be differentiated on each of these criteria. Growth hormone secretion falls rapidly immediately upon separation of pups from the dam, while robust rises in corticosterone secretion are delayed for many hours. In addition, growth hormone responses are observed earlier in ontogeny. Finally, active maternal behavior is required for normal growth hormone secretion in 10-day-old rat pups, while passive sensory stimuli associated with the dam can significantly reduce the corticosterone response to separation.

Effects of maternal and sibling deprivation on basal and stress induced hypothalamic-pituitary-adrenal components in the infant rat

“…Maternal deprivation affected 'basal' HPA tone resulting in a significant increase in AM plasma CORT levels on both PND 6 and 9. This is in accord with reports by Stanton et al [16], Levine et al [9] and Kuhn et al [6]. Maternal deprivation also enhanced the responsiveness of the HPA axis to further stressors.…”

Toward a Radically Embodied Neuroscience of Attachment and Relationships?

“…Short-term social isolation in rats is associated with increased activity, heart rate, respiration, corticosterone release (a stress substrate), and ultrasonic vocalizations (Shapiro and Salas, 1970;Hofer, 1984;Stanton et al, 1987). Long-term isolation is associated with decreases in growth enzymes, heart rate, and behavior and increases in stress response (Hofer, 1987;Kuhn et al, 1990;Rosenfeld et al, 1992). Hofer's (1987) research suggests that these specific effects of isolation can be modified or eliminated by the introduction of sensory stimulation mimicking the softness, warmth, and other sensory features of the dam and littermates (Blumberg et al, 1992).…”

Local Brain Functional Activity Following Early Deprivation: A Study of Postinstitutionalized Romanian Orphans

“…Similarly, early adverse experiences in humans are associated with elevated rates of major depression and other psychiatric disorders in adulthood (for review, see Kaufman et al, 2000). Maternal separation is a potent stressor as evidenced by behavior (Harlow et al, 1965;Harlow, 1969;Suomi, 1997;Newman and Bachevalier, 1997) and neuroendocrine response (Kuhn et al, 1990;Higley, 1992;Pihoker et al, 1993). Early primate models of social deprivation utilized paradigms involving total social deprivation throughout infancy and resulted in severe social and emotional disturbances, including aggression, motor stereotypies, and reproductive problems (Harlow et al, 1965).…”

“…Alterations in neurofilament protein immunoreactivity in the dentate gyrus granule cell layer of the hippocampus was observed in socially deprived monkeys compared with socially reared animals (Siegel et al, 1993). Prolonged maternal separation of rat pups resulted in increased limbic-hypothalamic-pituitaryadrenal axis activity (Kuhn et al, 1990;Pihoker et al, 1993) and increased reactivity to stressors during adulthood (Plotsky and Meaney, 1993). However, different strains of rats show different sensitivity to early stress, suggesting that long-term effects of stress are mediated by both exposure and genetic variables (reviewed by Anisman et al, 1998).…”