Locustatachykinin isoforms in the locust: distribution and quantification in the central nervous system and action on the oviduct muscle.

The presence of locustatachykinin (LomTK)-like immunoreactivity is demonstrated in the central nervous system (CNS) of Locusta migratoria with the use of a polyclonal antiserum raised against LomTK1. By developing a radioimmunoassay with the same antiserum, we have demonstrated picomolar amounts of LomTK-like material in the tissues of the central nervous system. In contrast, only femptomolar amounts of LomTK-like material are associated with the oviduct tissue. The relative amounts of the different LomTK isoforms in the brain and the abdominal ganglionic chain were examined by separating the native peptides on high-performance liquid chromatography and comparing their retention times to synthetic LomTK standards. The amounts of the different isoforms of LomTK differed between and within the two regions of the central nervous system. However, the ratios of the different isoform amounts were similar between the two regions. The myostimulatory activities of LomTKs 1 to 4 were characterized by using the locust oviduct bioassay. LomTKs 1, 2, and 3 appeared to be more efficacious than LomTK4.