Influence of electroejaculation on peripheral blood concentrations of corticosteroids, progesterone, LH, and testosterone in bulls.

Temporal relationships among serum concentrations of corticosteroids (CS), luteinizing hormone (LH), progesterone (P), and testosterone (T) were examined in ten bulls exposed to the stress of electroejaculation (EE). Concentrations of CS and P increased concomitantly among bulls to peak levels by 15 min post-EE and then declined to pre-EE levels between 2 and 4 hr after EE. Total number of LH and T peaks decreased from 24 and 18, respectively, during the 12-hr pre-EE period to 11 and 14 during the 12-h post-EE period. Mean concentration of LH decreased after EE until 4 hr post-EE when episodic LH secretion resumed and concentrations of CS and P had declined to pre-EE levels. Similarly, mean concentration of T declined after EE and then increased 6-8 hr post-EE in response to resumption of LH secretion. The temporal associations of elevated concentrations of CS and P with basal LH and T before EE, absence of T response to endogenous LH peaks, and the temporary absence of episodic LH and T peaks after EE, suggest that endogenous adrenal steroids may modulate secretion of T in the bull.