TY - JOUR
T1 - Effect of reproductive status on hypothalamic-pituitary-adrenal (HPA) activity and reactivity in male California mice (Peromyscus californicus)
AU - Harris, Breanna N.
AU - Saltzman, Wendy
N1 - Funding Information:
We would like to thank the UCR vivarium staff for their help in animal care. We also thank Vanessa Yang, Julia Cho, Omar Aldaas, Aaron Stamp, Dr. Trynke de Jong, Juan Pablo Perea-Rodriguez, Gavrielle Concepcion, and Dr. Miyetani Chauke for their help with various aspects of experimental preparation and data collection, and Brian Gray, Dr. Kris Kaiser, Dr. Zach Hohman, and Dr. Mark Chappell for their helpful comments on a previous draft of this manuscript. This work was supported by funds from the University of California, Riverside , and from NIH grant 1R21MH087806 .
PY - 2013/3/5
Y1 - 2013/3/5
N2 - Previous studies indicate that reproductive condition can alter stress response and glucocorticoid release. Although the functional significance of hypothalamic-pituitary-adrenal (HPA) axis modulation by breeding condition is not fully understood, one possible explanation is the behavior hypothesis, which states that an animal's need to express parental behavior may be driving modulation of the HPA axis. This possibility is consistent with findings of blunted activity and reactivity of the HPA axis in lactating female mammals; however, effects of reproductive status on HPA function have not been well characterized in male mammals that express parental behavior. Therefore, we tested this hypothesis in the monogamous and biparental California mouse. Several aspects of HPA activity were compared in males from three reproductive conditions: virgin males (housed with another male), non-breeding males (housed with a tubally ligated female), and first-time fathers (housed with a female and their first litter of pups). In light of the behavior hypothesis we predicted that new fathers would differ from virgin and non-breeding males in several aspects of HPA function and corticosterone (CORT) output: decreased amplitude of the diurnal rhythm in CORT, a blunted CORT increase following predator-odor stress, increased sensitivity to glucocorticoid negative feedback, and/or a blunted CORT response to pharmacological stimulation. In addition, we predicted that first-time fathers would be more resistant to CORT-induced suppression of testosterone secretion, as testosterone is important for paternal behavior in this species. We found that virgin males, non-breeding males and first-time fathers did not display any CORT differences in diurnal rhythm, response to a predator-odor stressor, or response to pharmacological suppression or stimulation. Additionally, there were no differences in circulating testosterone concentrations. Adrenal mass was, however, significantly lower in new fathers than in virgin or non-breeding males. These results suggest that the behavior hypothesis does not explain HPA function across reproductive conditions in male California mice. •Reproductive condition can alter the stress response and glucocorticoid release.•Tested the behavior hypothesis in males - virgins, non-breeding, first-time fathers•Groups did not differ in baseline, post-stress, post-DEX, or post-CRH CORT levels.•Adrenal mass was lower in new fathers than in virgin or non-breeding males.•The behavior hypothesis (need for parental behavior drives HPA change) - not supported.
AB - Previous studies indicate that reproductive condition can alter stress response and glucocorticoid release. Although the functional significance of hypothalamic-pituitary-adrenal (HPA) axis modulation by breeding condition is not fully understood, one possible explanation is the behavior hypothesis, which states that an animal's need to express parental behavior may be driving modulation of the HPA axis. This possibility is consistent with findings of blunted activity and reactivity of the HPA axis in lactating female mammals; however, effects of reproductive status on HPA function have not been well characterized in male mammals that express parental behavior. Therefore, we tested this hypothesis in the monogamous and biparental California mouse. Several aspects of HPA activity were compared in males from three reproductive conditions: virgin males (housed with another male), non-breeding males (housed with a tubally ligated female), and first-time fathers (housed with a female and their first litter of pups). In light of the behavior hypothesis we predicted that new fathers would differ from virgin and non-breeding males in several aspects of HPA function and corticosterone (CORT) output: decreased amplitude of the diurnal rhythm in CORT, a blunted CORT increase following predator-odor stress, increased sensitivity to glucocorticoid negative feedback, and/or a blunted CORT response to pharmacological stimulation. In addition, we predicted that first-time fathers would be more resistant to CORT-induced suppression of testosterone secretion, as testosterone is important for paternal behavior in this species. We found that virgin males, non-breeding males and first-time fathers did not display any CORT differences in diurnal rhythm, response to a predator-odor stressor, or response to pharmacological suppression or stimulation. Additionally, there were no differences in circulating testosterone concentrations. Adrenal mass was, however, significantly lower in new fathers than in virgin or non-breeding males. These results suggest that the behavior hypothesis does not explain HPA function across reproductive conditions in male California mice. •Reproductive condition can alter the stress response and glucocorticoid release.•Tested the behavior hypothesis in males - virgins, non-breeding, first-time fathers•Groups did not differ in baseline, post-stress, post-DEX, or post-CRH CORT levels.•Adrenal mass was lower in new fathers than in virgin or non-breeding males.•The behavior hypothesis (need for parental behavior drives HPA change) - not supported.
KW - Behavior hypothesis
KW - California mouse
KW - Corticosterone
KW - Glucocorticoid
KW - HPA axis
KW - Paternal behavior
KW - Peromyscus californicus
KW - Stress
UR - http://www.scopus.com/inward/record.url?scp=84875539253&partnerID=8YFLogxK
U2 - 10.1016/j.physbeh.2013.02.016
DO - 10.1016/j.physbeh.2013.02.016
M3 - Article
C2 - 23474132
AN - SCOPUS:84875539253
SN - 0031-9384
VL - 112-113
SP - 70
EP - 76
JO - Physiology and Behavior
JF - Physiology and Behavior
ER -