Proctolinergic innervation of the accessory gland in male crickets ( Gryllus bimaculatus): Detection of proctolin and some pharmacological properties of myogenically and neurogenically evoked contractions

Abstract

Spontaneous contractions were observed in the cricket male accessory gland which is innervated by dorsal unpaired median neurones (DUMR7 neurones) and paired neurones (LC neurones) arising from the terminal abdominal ganglion. These contractions were myogenic: identical mechanical activity was observable in a transplanted accessory gland which lacked innervation. Selective antidromic electrical stimulation of the DUMR7 neurones evoked a contraction of the accessory gland, which was graded and dependent upon both frequency and duration of stimulation. Glutamate at 10 −4 M, and proctolin, at low concentrations of 10 −9 M, produced sustained contractions of the accessory gland. These drugs at higher concentrations (glutamate, > 10 −4 M; proctolin, > 10 −8 M) reduced the amplitude of neurogenically evoked contractions and increased the basal tonus. Octopamine, at 10 −7 M, increased the frequency of myogenically evoked contractions. Application of serotonin, at 10 −5 M, reduced the amplitude of neurally evoked contractions and also resulted in a lowering of the basal tonus. By use of high-performance liquid chromatoraphy and bioassay we have found that proctolin was present in the accessory gland, and it was released from the accessory gland in response to the application of high K + saline. No proctolin was detected in the transplanted accessory gland.