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Adult female rats castrated 4 weeks before were implanted bilaterally into the basomedial area of the amygdala with drugs known to mimic or to counteract the actions of acetylcholine. The animals were sacrificed at different time intervals after the implantation of the different compounds, and serum levels of LH and FSH were measured by radioimmunoasay. The data obtained indicate that the intra-amygdalar implantation of the muscarinic blocker atropine induces a significant increase of the release of LH without altering FSH secretion. The implantation of two cholinomimetic drugs, pilocarpine, an almost pure muscarinic agonist, and carbachol, which possesses both muscarinic and nicotinic properties, exerted an inhibitory effect only on LH release. On the contrary, the intra-amygdalar placement of the nicotinic blocker mecamylamine was followed by an increase of FSH with no changes in LH. These observations may suggest that cholinergic signals reaching the amygdala may be of some relevance in the mechanisms controlling gonadotrophin secretion. Muscarinic receptors seem to play an inhibitory role in the regulation of LH secretion, while nicotinic receptors seem to modulate in an inhibitory way FSH release.

A colorimetric method has been developed for the rapid characterization and precise determination of ethynodiol diacetate in an estrogen-progestin combination using antimony trichloride reagent. The results obtained demonstrate the specificity of this reaction for ethynodiol diacetate compared with other substances with progestinic action often used in these combinations. Furthermore, the results prove the reliability and practicality of this reaction as well as the complete lack of interferences from the estrogen fraction present in these formulations.