Photoperiod-induced differential expression of angiogenesis genes in testes of adult Peromyscus leucopus

Non-pathological angiogenesis in adults is rare and is largely thought to be restricted to wound healing and female reproductive cycles. Adult male rodents, however, display seasonal angiogenesis to support seasonal changes in reproductive tissue morphology. Non-tropical rodents use photoperiod (day length) to determine the time of year. During short days, the reproductive system undergoes involution and mating behaviours stop, adaptations which presumably allow energy resources to be shifted to processes necessary for winter survival. We compared the patterns of gene expression involved in angiogenesis in testes of white-footed mice (Peromyscus leucopus) following 7, 14, 21 or 34 weeks of long or short day lengths. Short days decreased body mass, reproductive tract mass and seminiferous tubule diameter. Potential genes involved in seasonal angiogenesis were screened by hybridizing testicular RNA from each group to angiogenesis-specific microarrays. Genes that were > or =6-fold different between long- and short-day testes (i.e. hypoxia-inducible factor 1alpha(Hif1alpha), plasminogen activator inhibitor 1 (Serpine1), transforming growth factor beta receptor 3 (Tgfbetar3) and tumour necrosis factor (Tnf )) were sequenced and expression differences were compared throughout gonadal regression and recrudescence using quantitative RT-PCR. Our results suggest that short days trigger expression of Hif1alpha, Serpine1, and Tgfbetar3 to inhibit angiogenesis or promote apoptosis during testicular regression, and also trigger expression of Tnf to promote angiogenesis during testicular recrudescence.