Meeting Abstract
P2.96 Tuesday, Jan. 5 Experience with photostimulation upregulates vasoactive intestinal polypeptide in the hypothalamus of female house finches ALDREDGE, RA*; SALVANTE, KG; SEWALL, KB; SOCKMAN, KW; Univ. of North Carolina, Chapel Hill; Simon Fraser Univ., British Columbia; Univ. of North Carolina, Chapel Hill; Univ. of North Carolina, Chapel Hill aldredge@email.unc.edu
For many temperate breeding birds, reproductive output increases with age. Older birds tend to breed earlier and lay larger clutches than younger birds. Previous research suggests that first-year females that experience photostimulation for the second time upregulate several components of reproductive development more quickly or robustly than first-year females experiencing photostimulation for the first time. The hypothalamic neuropeptide vasoactive intestinal polypeptide (VIP) plays an important role in the photoperiodic regulation of avian reproductive development and behavior, principally by regulating pituitary secretion of prolactin (PRL). PRL increases in photostimulated birds and changes in PRL are correlated with different stages of the avian reproductive cycle. We tested whether prior experience with photostimulation influenced expression of hypothalamic VIP in the house finch (Carpodacus mexicanus). We predicted that VIP expression would be higher in first-year birds with prior photostimulation experience because early breeders would need elevated PRL levels earlier in the season. As predicted, first-year females with photostimulation experience had higher hypothalamic VIP immunoreactivity (VIP-ir) than first-year females that were experiencing photostimulation for the first time. Photostimulation experience did not influence VIP-ir in males, possibly because male house finches use other cues to time PRL release. These results suggest that VIP joins the list of reproductive factors that develop early or more robustly in females with photostimulation experience, which may explain the increase in reproductive output with age.
