Summary. Ovulation was induced in aminophylline-treated rats by different stimuli acting upon the pituitary gland (LH-RH in pro-oestrous rats treated with chlorpromazine), ovary (LH in pro-oestrous rats treated with chlorpromazine or hypophysectomized) or ovary and pituitary gland (PMSG in immature rats). In the different assays, the proportion of ovulating rats and the number of eggs ovulated were augmented by aminophylline treatment. Immature rats injected with aminophylline 1 day after priming with PMSG had, between 18:00 and 20:00 h, significantly higher blood LH levels than did controls.
Chlorpromazine injected at 10:00 h on the day of pro-oestrus inhibited ovulation and suppressed the LH surge normally observed at 18:00 h. However, aminophylline injected at 13:00 h re-established ovulation and induced within 1 h a slight LH secretion.
The results indicate that aminophylline affects both pituitary gland and ovary, supporting the concept that their cAMP levels play a significant biological role in the magnitude of the ovulatory response.