Antler cycle and thermolabile and thermostable alkaline phosphatase in white-tailed deer; circannual and circadian rhythms and variation after thyroxine, dexamethasone and ACTH administration.

The plasma levels of thermolabile (TLAP) and thermostable (TSAP) alkaline phosphatase were investigated in adult male white-tailed deer. Distinct seasonal variation of TLAP (with highly elevated levels in July) were observed, whereas TSAP exhibits low concentration with a small increase in October. No circadian rhythm was found for TLAP or TSAP. A close correlation (r = 0.98) between TLAP activity and antler weight was found. Administration of ACTH or dexamethasone were ineffective in influencing AP activity. On the other hand, variations of triiodothyronine (T3) levels in plasma induced by thyroxine (T4) injections correlated well with concentration of TLAP.