Publication Date


Document Type


Committee Members

Michael Hennessy (Committee Chair), Patricia Schiml (Committee Member), Barbara Kraszpulska (Committee Member)

Degree Name

Master of Science (MS)


In the guinea pig, the ability of the mother’s presence to buffer hypothalamic-pituitary- adrenal (HPA) axis activation in her young during exposure to stressful stimuli has been well documented. Under similar testing conditions, other conspecifics (littermates, other adult females) are less effective in doing so. The effect does seem to wane with age but is still present to a significant degree in offspring approaching adolescence. However, we recently observed that an unfamiliar adult male buffered HPA axis activation and increased Fos expression in the prefrontal cortex of preweaning infants exposed to a novel enclosure at both 60 and 120 minutes but did not buffer HPA axis activation in periadolescent guinea pigs tested at 60 minutes. Here, we found that an unfamiliar adult male buffered mean plasma cortisol levels in periadolescent guinea pigs exposed to a novel enclosure at 120 minutes. Social interactions between the adult male and periadolescent were observed with the periadolescent vocalizing less but exhibiting more passive behavior and locomotion than when alone. Fos values in the prefrontal cortex were lower than values measured in prior studies and were not affected by the presence of the male. In summary, unfamiliar adult males are, in fact, capable of buffering plasma cortisol responses in periadolescent guinea pigs if given a sufficient amount of time for the effect to be detected. We found no evidence that this buffering was mediated by increased prefrontal activity.

Page Count


Department or Program

Department of Neuroscience, Cell Biology and Physiology

Year Degree Awarded


Included in

Anatomy Commons