Influence of the maternal surrogate on pituitary–adrenal activity and behavior of infant squirrel monkeys

Abstract

Squirrel monkey infants reared on surrogates showed an increase in vocalizations, but no change in plasma cortisol levels when the surrogate was removed from the home cage for .5 hr. When the infant was exposed to novelty during separation, there was a further increase in vocalizations, as well as increases in movement and plasma cortisol. Placing the surrogate with the infant in the novel environment reduced the behavioral reaction and led to high levels of infant-surrogate contact; however, plasma cortisol levels were as high at .5 hr as when the infant was in the novel environment alone. With longer (2-4 hr) exposures to the novel room, cortisol elevations were attenuated by the presence of the surrogate. When the infant was alone, levels of cortisol, but not protest behavior, increased with length of exposure to the novel room. These results indicate that the physiological reaction to separation procedures in infant primates may not be safely inferred from behavioral responses, and, together with earlier findings, suggest a deficiency in the attachment of surrogate-reared infants.

Behavioral and autonomic responses to peer separation in pigtail macaque monkey infants

“…Several other studies have also found fewer physiological effects of separation from nonmaternal attachment figures, including cortisol, HR, BT, and sleep measures in peer-and surrogate-reared infants (Hennessy , Mendoza, & Kaplan, 1982;Hennessy & Kaplan, 1982;Reite, Short, & Seiler, 1978). The problem remains, however, to explain prior peer separation studies which report despair (e.g., Mineka et al, 1981;Suomi et al, 1970).…”

Rearing condition and plasma cortisol in rhesus monkey infants

“…Also, previous studies have found that the nature of the attachment relationship to an inanimate surrogate differs from that of the attachment to a mother or a peer in several important aspects. Studies have indicated that, although separation in an unfamiliar environment elicits HPA activation, removal of the surrogate from the home cage does not [squirrel monkey Hennessy & Kaplan, 1982]. In contrast, mother-reared infants whose mothers are removed from the home cage do exhibit cortisol increments.…”

Evidence that endogenous corticotropin-releasing factor suppresses behavioral responses of guinea pig pups to brief isolation in novel surroundings

“…In both primates (Hennessy & Kaplan, 1982;Levine, (Hennessy et al, 1995). Finally, McInturf and Hennessy (1996) recently demonstrated that SC injec- Wiener, & Coe, 1993;Wiener, Johnson, & Levine, 1987) and guinea pigs (Hennessy & Moorman, tion of just a CRF-receptor antagonist elevated levels of vocalizing and locomotor activity during 1989), the highest level of infant vocalizing is seen shortly after separation ensues, with levels genera subsequent 60-min separation.…”

“…However, CRF did not induce prolonged freezing or other behaviors instudies have all used guinea pigs near the age of weaning, Experiment 3 examined the effect of compatible with the vocalization or locomotor responses (Becker & Hennessy, 1993), and pups in-CRF-receptor blockade in pups isolated during their 1st week of life. The antagonist used was Djected with CRF performed as well as controls in a forced-swim test (Becker & Hennessy, 1993), Phe-CRF 12-41 (CRF 12-41 ;Curtis, Grigoriadis, Page, Rivier, & Valentino, 1994), which appears to have demonstrating that CRF did not simply reduce little or no intrinsic biological activity (Howard, ''whistle'' vocalizations (Berryman, 1976) was talMenzaghi, Heinrichs, River, & Koob, 1993), so lied with a hand counter. This vocalization is charthat observed effects can be interpreted as reveracteristic of pups during separation and may serve sals of the effects of endogenous CRF activity.…”

“…CRF was also found to suppress locoantagonist could potentially produce opposing behavioral outcomes. Experiment 2 asked whether motor activity immediately following separation (Becker & Hennessy, 1993;Hennessy, Long, Nigh, blockade of CRF receptors would affect behavior in nonisolated pups. Finally, because our earlier Williams, & Nolan, 1995).…”