Autonomic nervous control of endometrial secretion in the guinea pig

Secretory responses of the guinea pig endometrium to field stimulation of nerves and/or drugs were studied throughout oestrous cycle. Secretory responses are dependent on the hormonal state of the animals and are seen at oestrus, metoestrus and at implantation time. The cholinergic nature of the secretory innervation was confirmed. Optimal secretory response was found at 0.5 or 1 Hz continuous stimulation. Adrenergic inhibition was revealed at metoestrus (day 3-5), The alpha-adrenergic inhibitory influence had its optimal frequency at 0.5 Hz. The inhibition seemed to be both prejunctional and postjunctional. VIP increased endometrial secretion, the effect was probably preterminal. Burst stimulation at any frequency gave less (or no) secretory responses under these experimental conditions. The complex organization of the endometrial innervation is apparent.