AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 4 804-R810, Copyright © 1993 by American Physiological Society
Primary structures and effects on gastrointestinal motility of tachykinins from the rainbow trout
J. Jensen, K. R. Olson and J. M. Conlon
Department of Biomedical Sciences, Creighton University, Omaha, Nebraska 68178.
Purification and structural characterization of tachykinins from rainbow
trout (Oncorhynchus mykiss) intestine has demonstrated the presence of
three different peptides related to the mammalian tachykinins: substance P,
neurokinin A, and neuropeptide-gamma. The substance P- and the neurokinin
A-related peptides present in the intestine are identical to the
tachykinins previously isolated from the trout brain. The
neuropeptide-gamma-related peptide
(Ser-Ser-Ala-Asn-Pro-Gln-Ile-Thr-Arg-Lys-Arg-His-Lys-Ile-Asn-Ser-Phe-
Val-Gly-Leu-Met-NH2), not previously identified in brain tissue, has the
sequence of the neurokinin A-related tachykinin at its COOH-terminus. Both
trout substance P and neurokinin A stimulated the motility of isolated
trout intestinal muscle [pD2(-log of EC50) values 8.5 +/- 0.15 and 7.35 +/-
0.08, respectively] and the vascularly perfused trout stomach (pD2 values
9.63 +/- 0.23 and 8.18 +/- 0.23, respectively). Trout substance P was 14
times more potent than trout neurokinin A in the intestine and 28 times
more potent in the stomach. The data suggest that receptors interacting
with tachykinins in the trout gastrointestinal tract have a similar
selectivity as the mammalian NK-1 receptor.
