Adult males buffer the cortisol response of young guinea pigs: Changes with age, mediation by behavior, and comparison with prefrontal activity.
In the guinea pig, the presence of the mother buffers hypothalamic-pituitary-adrenal (HPA) responses of her young during exposure to a novel environment, and can do so even if she is anesthetized. In contrast, under comparable conditions other conspecifics (siblings, other adult females) are less effective or ineffective in doing so. However, we recently observed that an unfamiliar adult male reduced plasma cortisol elevations and increased Fos in the prefrontal cortex of preweaning pups exposed to a novel enclosure for 120min. Here we found adult males buffered the adrenocortical response of preweaning pups at 60 as well as 120min and of periadolescent guinea pigs if exposure was of 120min. Further, because males vigorously engaged in social interactions with the young during exposure, we examined the effect of behavior by comparing the impact of conscious and unconscious (anesthetized) adult males. When tested with a conscious but not unconscious male, pups exhibited reduced plasma cortisol elevations. Pups, particularly females, had greater Fos induction in the prefrontal cortex when with a conscious versus unconscious adult male. Overall, we found that an unfamiliar adult male can buffer the cortisol response of guinea pigs both before and after weaning, though more-prolonged exposure appears necessary in the older animals. Further, unlike buffering by the biological mother, the effect of the male is mediated by behavioral interactions. Thus, the buffering of the infant guinea pig's cortisol response by the mother and an unfamiliar adult male involve different underlying mechanisms.
['Hennessy|Michael B|MB|', 'Watanasriyakul|W Tang|WT|', 'Price|Brittany C|BC|', 'Bertke|Alexander S|AS|', 'Schiml|Patricia A|PA|']
D000367:Age Factors D000818:Animals D000833:Animals, Suckling D001522:Behavior, Animal D005260:Female D006168:Guinea Pigs D006854:Hydrocortisone D007398:Interpersonal Relations D008297:Male D009035:Mothers D009425:Nesting Behavior D017397:Prefrontal Cortex D012737:Sex Factors D014828:Vocalization, Animal D014886:Weaning
Cortisol guinea pig Hypothalamic-pituitary-adrenal Prefrontal cortex Infralimbic Prelimbic Social buffering Social development