The pineal gland and the photoperiodic control of luteinizing hormone secretion in intact and castrated Japanese quail

The effects of pinealectomy on a range of photoperiodic responses were investigated in male Japanese quail by measuring plasma LH concentrations in intact, sham-operated and pinealectomized birds in the following four experiments: 91) transfer of sexually quiescent birds from a short photoperiod of 8 h light:16 h darkness (8L:16D) to a photostimulatory daylength of 16L:8D; (2) transfer of sexually mature birds frin 16L:8D to 8L:16D; (3) castration in 16L:8D and exposure to 13L:11D; (4) castration in 8L:16D and exposure to 13L:11D. There was no evidence of effects of the pineal gland on the photoperiodically induced changes in LH secretion, the quantitative relationship between LH secretion and photoperiod in intact and castrated birds, or the induction of relative photorefractoriness by prolonged exposure to 16L:8D. This suggests that there is no pineal influence on the photoperiodic clock or its effectors in this bird.