Fig. 6. Flight initiation and amine depletion. (A,B) Photomicrographs of sagittal sections of a thoracic ganglion (anterior left, dorsal top) processed for octopamine immunocytochemistry. (A) In DMSO-treated locusts the well-known octopaminergic DUM neurones, for example, are strongly labelled (arrow, Nomarski optics) and immunoreactive varicosities are visible in the dorsal neuropil (insert, normal light microscopy). (B) Corresponding sections from a reserpine pre-treated animal verifies effective depletion of octopamine from the nervous system (arrow: unlabelled DUM neurone; insert: same neuropil region as in A). (C) Wind- and (D) pilocarpine (5 mmol l^–1, bath applied)-induced flight motor activity in deafferented locust preparations pre-treated with 500 µg reserpine (top traces: initial response; lower traces: expanded excerpts, as in Fig. 1). Scale bars, A,B 100 µm; C,D 10 s upper traces, 100 ms lower traces.