Peptidergic innervation of insect skeletal muscle: Immunochemical observations
Article first published online: 9 OCT 2004
Copyright © 1985 Alan R. Liss, Inc.
Journal of Comparative Neurology
Volume 242, Issue 1, pages 93–101, 1 December 1985
How to Cite
Witten, J. L. and O'Shea, M. (1985), Peptidergic innervation of insect skeletal muscle: Immunochemical observations. J. Comp. Neurol., 242: 93–101. doi: 10.1002/cne.902420106
- Issue published online: 9 OCT 2004
- Article first published online: 9 OCT 2004
- Manuscript Accepted: 17 JUL 1985
- neuromuscular junction;
- slow muscles;
Proctolin (Arg-Tyr-Leu-Pro-Thr) is a pentapeptide present in the hindgut or proctodeum of the cockroach Periplaneta americana where it may be a transmitter. Its widespread distribution among peripherally projecting neurons in the CNS (Bishop and O'Shea, '82) suggested that proctolin's motor function is not restricted to the hindgut, but has a variety of peripheral targets. This idea was further supported when proctolin was localized to an identified skeletal motoneuron, the slow coxal depressor, where it acts as a cotransmitter (O'Shea and Bishop, '82; Adams and O'Shea, '83). Our objective was to investigate the proctolinergic innervation of a variety of skeletal muscles of the cockroach Periplaneta americana. We used immunohistochemical and radioimmunochemical methods to map the distribution of proctolin immunoreactivity. This survey revealed that a subpopulation of skeletal muscles are innervated by proctolinergic motoneurons. The anatomical features of the peptidergic innervation and the levels of proctolin-like immunoreactivity of one muscle group, the coxal depressor system, are here described in detail. The source of the proctolin innervation to the metathoracic coxal depressor group is identified as the slow coxal depressor motoneuron. The results of a survey of fast and slow skeletal muscles revealed that proctolin is associated with slow motor function. The functional implications of the association of a peptide with motoneurons are discussed in relationship to the organization of the insect motor pool.