Meeting Abstract
In female mammals, reproduction changes energetic demands, metabolism, and morphology. In species in which males assist with rearing offspring, reproduction could potentially be associated with metabolic, energetic, and morphological changes in fathers; however, this has rarely been addressed. We examined effects of an energetic stressor on metabolically important physiological, morphological, and behavioral measures, and whether these effects differ between breeding and nonbreeding males, in the biparental California mouse. Males were paired with an ovary-intact female, an ovariectomized female that was treated with estrogen and progesterone to induce estrus, or an ovariectomized female that was not hormone-treated. Within each group, half of the animals were housed under standard laboratory conditions and the other half in cages requiring them to climb wire mesh towers to obtain food and water; in addition, these latter animals were fasted for 24 hours every third day. Based on animals completed so far, males housed under energetic challenge had increased body mass, fat mass, and relative liver mass, along with decreased relative triceps surae mass, compared to controls. The energetic challenge also increased blood lipid content and pain sensitivity. Only relative testis mass showed a reproductive condition x housing interaction: energetic challenge decreased testis mass in non-breeding males, but breeding males were unaffected. We found no other statistically significant differences among reproductive conditions. These results indicate that our energetic-challenge paradigm had numerous metabolic and morphological effects, but that these effects were rarely modulated by reproductive condition.
