Rehousing Periadolescent Male Guinea Pigs (\u3cem\u3eCavia porcellus\u3c/em\u3e) Apart From Their Mothers for 24 Hours Increases Maternally Directed Sexual Behavior and Plasma Testosterone

Periadolescent male guinea pigs (Cavia porcellus) housed continuously with their mother displayed little or no sexual behavior when they were tested with her in a novel environment.However, if males were rehoused without their mother for 24 hr before testing, they frequently directed courtship and sexual behavior toward her. This effect occurred whether the mother was isolated or not during the rehousing period. In addition, rehousing without the mother produced a significant rise in the plasma testosterone levels of the males. It appears that continuous housing with the mother inhibits sexual and courtship behavior directed toward her, as well as gonadal activity, in periadolescent male guinea pigs. These effects may serve to prevent inbreeding

Development of Selective Social Buffering of the Plasma Cortisol Response in Laboratory-Reared Male Guinea Pigs (\u3cem\u3eCavia porcellus\u3c/em\u3e)

The authors examined the effect of different classes of females on the plasma cortisol response of male guinea pigs (Cavia porcellus) from shortly after weaning through full adulthood. Males housed under standard laboratory conditions with artificial harems of 2 unrelated females of similar age were tested at 4 age ranges (~Days 40, 120, 180, and 240). At each age range, males were placed into a novel environment for 2 hr on 4 separate occasions: while alone, with 1 female cage mate, with the other female cage mate, or with an unfamiliar female. Relative preference for the 2 female cage mates was determined from observations in the home cage. Puberty was estimated by plasma testosterone levels. At the 3 youngest ages, the more preferred, less preferred, and unfamiliar females did not differentially reduce the plasma cortisol response. At 240 days of age, only the presence of the more preferred female was able to significantly reduce cortisol levels. These results demonstrate a very selective social buffering effect on the plasma cortisol response in a nonmonogamous species. This effect emerges well after sexual maturity and can be observed under standard laboratory housing

Rehousing Periadolescent Male Guinea Pigs (\u3cem\u3eCavia porcellus\u3c/em\u3e) Apart From Their Mothers for 24 Hours Increases Maternally Directed Sexual Behavior and Plasma Testosterone

Periadolescent male guinea pigs (Cavia porcellus) housed continuously with their mother displayed little or no sexual behavior when they were tested with her in a novel environment.However, if males were rehoused without their mother for 24 hr before testing, they frequently directed courtship and sexual behavior toward her. This effect occurred whether the mother was isolated or not during the rehousing period. In addition, rehousing without the mother produced a significant rise in the plasma testosterone levels of the males. It appears that continuous housing with the mother inhibits sexual and courtship behavior directed toward her, as well as gonadal activity, in periadolescent male guinea pigs. These effects may serve to prevent inbreeding

Development of Selective Social Buffering of the Plasma Cortisol Response in Laboratory-Reared Male Guinea Pigs (\u3cem\u3eCavia porcellus\u3c/em\u3e)

The authors examined the effect of different classes of females on the plasma cortisol response of male guinea pigs (Cavia porcellus) from shortly after weaning through full adulthood. Males housed under standard laboratory conditions with artificial harems of 2 unrelated females of similar age were tested at 4 age ranges (~Days 40, 120, 180, and 240). At each age range, males were placed into a novel environment for 2 hr on 4 separate occasions: while alone, with 1 female cage mate, with the other female cage mate, or with an unfamiliar female. Relative preference for the 2 female cage mates was determined from observations in the home cage. Puberty was estimated by plasma testosterone levels. At the 3 youngest ages, the more preferred, less preferred, and unfamiliar females did not differentially reduce the plasma cortisol response. At 240 days of age, only the presence of the more preferred female was able to significantly reduce cortisol levels. These results demonstrate a very selective social buffering effect on the plasma cortisol response in a nonmonogamous species. This effect emerges well after sexual maturity and can be observed under standard laboratory housing

Presence of Mother and Unfamiliar Female Alters Levels of Testosterone, Progesterone, Cortisol, ACTH and Behavior in Maturing Guinea Pigs

Although the guinea pig is characterized by precocial physical development and minimal active maternal care, studies suggest the presence of the mother can influence neuroendocrine and behavioral activity of offspring even well beyond weaning. Previous results may have been influenced by the procedure of housing weaned subjects with the mother to within 2 days of testing. The present study examined ∼40-day-old guinea pigs housed apart from the mother for 0 (not rehoused), 2, or 10 days. Rehousing without the mother led to elevations in plasma testosterone (measured in males), progesterone (measured in females), cortisol, and adrenocorticotropin (ACTH) (both measured in males and females). Offspring housed without the mother for 10 days had the highest progesterone, cortisol, and ACTH levels. Testosterone elevations were observed in 2-day-, but not 10-day-, rehoused animals. Regardless of rehousing condition, 60 min isolation in a novel test cage elevated progesterone, cortisol, and ACTH, and reduced testosterone. These effects were all moderated if the subject was tested with the mother or another female. Sexual behavior toward the mother was observed frequently, but only in males housed apart from her prior to testing. Overall, males and females that had been housed apart from the mother interacted with her as they would an unfamiliar female. Our results corroborate previous findings, suggest the effect of housing apart from the mother on male testosterone is transitory, and indicate that continuous housing with the mother past weaning suppresses circulating progesterone in females and cortisol and ACTH in both sexes

Social Buffering of the Cortisol Response of Adult Female Guinea Pigs

When housed in spacious, mixed age/sex colonies, male guinea pigs form small harems of females with which attachment-like social bonds are established. A previous study indicated that the bonded male, but not an unfamiliar male from the same colony, could reduce the plasma cortisol response of a female when exposed to a novel environment. We examined the effect of several classes of social partners on the cortisol response of females maintained under standard laboratory housing conditions. Eight “artificial harems” comprised of one adult male and two adult females were formed in standard group-housing cages 2 weeks prior to the study. Behavior observed in these home cages indicated that interactions between males and females of the triads were overwhelmingly positive in nature. When exposed to a novel environment for 2 h, the presence of either the male or female cage mate reduced the subject female\u27s plasma cortisol response, whereas the presence of an unfamiliar adult male did not. Changes in plasma cortisol levels were not predicted by the frequency of various social behaviors observed in the novel environment. These findings: (1) demonstrate that the buffering effect of male partners on the cortisol response of adult females can be observed in guinea pigs maintained in conventional laboratory housing; (2) indicate that unfamiliar adult males are ineffective at reducing cortisol responses of females under these conditions; and, (3) appear to be the first to show buffering effects by adult female guinea pigs on the cortisol responses of other adult females

Social Buffering of the Cortisol Response of Adult Female Guinea Pigs

When housed in spacious, mixed age/sex colonies, male guinea pigs form small harems of females with which attachment-like social bonds are established. A previous study indicated that the bonded male, but not an unfamiliar male from the same colony, could reduce the plasma cortisol response of a female when exposed to a novel environment. We examined the effect of several classes of social partners on the cortisol response of females maintained under standard laboratory housing conditions. Eight “artificial harems” comprised of one adult male and two adult females were formed in standard group-housing cages 2 weeks prior to the study. Behavior observed in these home cages indicated that interactions between males and females of the triads were overwhelmingly positive in nature. When exposed to a novel environment for 2 h, the presence of either the male or female cage mate reduced the subject female\u27s plasma cortisol response, whereas the presence of an unfamiliar adult male did not. Changes in plasma cortisol levels were not predicted by the frequency of various social behaviors observed in the novel environment. These findings: (1) demonstrate that the buffering effect of male partners on the cortisol response of adult females can be observed in guinea pigs maintained in conventional laboratory housing; (2) indicate that unfamiliar adult males are ineffective at reducing cortisol responses of females under these conditions; and, (3) appear to be the first to show buffering effects by adult female guinea pigs on the cortisol responses of other adult females

Consequences of the Presence of the Mother or Unfamiliar Adult Female on Cortisol, ACTH, Testosterone and Behavioral Responses of Periadolescent Guinea Pigs During Exposure to Novelty

Periadolescent guinea pigs were exposed to a novel environment for 10, 30, 60, or 90 min while either alone or with either their biological mother or an unfamiliar adult female. Both classes of females reduced plasma cortisol, ACTH and vocalization responses to the novel environment, and did so to an equivalent degree. However, behavioral interactions with the mother and unfamiliar female differed considerably. The offspring exhibited more defensive behavior and were the targets of more agonistic acts when with the unfamiliar female, though one agonistic behavior, kicking, was observed more often in tests with the mother. Males displayed more social/courtship behavior and tumescence with the unfamiliar female. Further, males exhibited higher plasma testosterone levels when with the unfamiliar female than when either with the mother or alone. These data in conjunction with earlier findings suggest that the ability of unfamiliar adult females to moderate hypothalamic–pituitary–adrenal activity fully emerges during the periadolescent period, is not dependent on nurturant behavior by the adult female, and may facilitate the redirection of social behavior from the mother to unrelated adults. Further, mothers appear to inhibit maternally directed sexual behavior and plasma testosterone elevations in their periadolescent sons, effects which likely serve to inhibit inbreeding. Ó 2000 Elsevier Science Ltd. All rights reserved

Consequences of the Presence of the Mother or Unfamiliar Adult Female on Cortisol, ACTH, Testosterone and Behavioral Responses of Periadolescent Guinea Pigs During Exposure to Novelty

Periadolescent guinea pigs were exposed to a novel environment for 10, 30, 60, or 90 min while either alone or with either their biological mother or an unfamiliar adult female. Both classes of females reduced plasma cortisol, ACTH and vocalization responses to the novel environment, and did so to an equivalent degree. However, behavioral interactions with the mother and unfamiliar female differed considerably. The offspring exhibited more defensive behavior and were the targets of more agonistic acts when with the unfamiliar female, though one agonistic behavior, kicking, was observed more often in tests with the mother. Males displayed more social/courtship behavior and tumescence with the unfamiliar female. Further, males exhibited higher plasma testosterone levels when with the unfamiliar female than when either with the mother or alone. These data in conjunction with earlier findings suggest that the ability of unfamiliar adult females to moderate hypothalamic–pituitary–adrenal activity fully emerges during the periadolescent period, is not dependent on nurturant behavior by the adult female, and may facilitate the redirection of social behavior from the mother to unrelated adults. Further, mothers appear to inhibit maternally directed sexual behavior and plasma testosterone elevations in their periadolescent sons, effects which likely serve to inhibit inbreeding. Ó 2000 Elsevier Science Ltd. All rights reserved

Presence of Mother and Unfamiliar Female Alters Levels of Testosterone, Progesterone, Cortisol, ACTH and Behavior in Maturing Guinea Pigs

Although the guinea pig is characterized by precocial physical development and minimal active maternal care, studies suggest the presence of the mother can influence neuroendocrine and behavioral activity of offspring even well beyond weaning. Previous results may have been influenced by the procedure of housing weaned subjects with the mother to within 2 days of testing. The present study examined ∼40-day-old guinea pigs housed apart from the mother for 0 (not rehoused), 2, or 10 days. Rehousing without the mother led to elevations in plasma testosterone (measured in males), progesterone (measured in females), cortisol, and adrenocorticotropin (ACTH) (both measured in males and females). Offspring housed without the mother for 10 days had the highest progesterone, cortisol, and ACTH levels. Testosterone elevations were observed in 2-day-, but not 10-day-, rehoused animals. Regardless of rehousing condition, 60 min isolation in a novel test cage elevated progesterone, cortisol, and ACTH, and reduced testosterone. These effects were all moderated if the subject was tested with the mother or another female. Sexual behavior toward the mother was observed frequently, but only in males housed apart from her prior to testing. Overall, males and females that had been housed apart from the mother interacted with her as they would an unfamiliar female. Our results corroborate previous findings, suggest the effect of housing apart from the mother on male testosterone is transitory, and indicate that continuous housing with the mother past weaning suppresses circulating progesterone in females and cortisol and ACTH in both sexes