Juvenile friends, behavior, and immune responses to separation in bonnet macaque infants.

Individual differences in the response to maternal separation in nonhuman primate infants have been attributed to (among other variables) presence or absence of processes that may model social support in humans. Alternative attachments to other members of the social group buffer the infant against a depressive response to maternal separation. This hypothesis was tested in a group of bonnet macaques by manipulating the presence or absence of alternative juvenile attachment figures (friends) during separation. Infants who retained such attachments showed fewer behavioral evidences of depression when separated from their mothers. These infants without friends also showed changes in lymphocyte activation by mitogens or natural cytotoxicity that were not evident in the infants with juvenile friends. Across all separated infants, natural cytotoxicity was positively correlated with juvenile affiliative behavior directed toward the infants during the separation. These results support the hypothesis that social support, available from alternative attachments, can modulate the response to loss, and can account for some of the individual differences seen in these responses.

Immune responses following competitive water tests in two species of macaques.

A panel of immune parameters (lymphocyte activation by mitogens, natural cytotoxicity, and differential cell counts) was assessed in socially housed pigtail and bonnet macaques 1 and 2 weeks before, 48 h after, and 1 and 2 weeks after a competitive water test. Species differences were found in both baseline measures and the responses to the test: Immune measures observed during baseline periods were lower in pigtail macaques. Furthermore, only the pigtail macaques showed changes in mitogen activation and cytotoxicity at 48 h post-test. Dominance-related behaviors affected these responses both within and across social groups. The species differences may be accounted for by the differences in the behavioral responses of the two species to the test: Pigtail macaques consistently contested access to the water during the test, whereas bonnet macaques did not. These results suggest that the immune system can be modulated by psychosocial behavioral systems, particularly during times of stress.

Induction of cloacal and dermal skin glands of tiger salamander larvae, (Ambystoma tigrinum): effects of testosterone and prolactin.

Treatment of male and female tiger salamander larvae with testosterone (0.3 micrograms/g body weight/day) induced precocious formation of ventral cloacal glands and stimulated proliferation and differentiation of mucous and granular (serous) glands in the ventral dermis of the skin. Lower doses of testosterone produced no visible glandular effects but did cause hyperemia and edema in the cloacal region. Prolactin (0.5 micrograms/g body weight/day) enhanced the action of testosterone on the cloacal glands, increasing both the amount of gland induced and the degree of glandular secretion. There was no apparent effect of prolactin alone on cloacal glands or any effect of prolactin with or without testosterone on the dermal glands. The possible homology of the amphibian ventral cloacal gland to the mammalian prostate gland is discussed.