Comparative characterisation of neuropeptide Y (NPY) from the brain of the rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta)

109 ELEVATED PLASMA LEVELS OF GASTRIN FOUND IN THE PRESENCE OF HELICOBACTER PYLORI INFECTION ARE PREDOMINANTLY DUE2TO THE ELEVA~IO~ OF GASTRIN-17. Ardill JES , Fillmore D , Chittallu RS , McColl KEL , -Department of ~edicine, Royal Victoria Hospital and The Queen's university of Belfast, University Department of Biochemistry, and -University Department of Medicine and Therapeutics, Western Infirmary, Glasgow. We have studied the molecular species of gastrins in a group of H Pylori positive duodenal ulcer patients, before and one month after eradication of the infection (n=13). Gastrins have been examined both basally and post prandially. Three gastrin antisera were used. R98 which is C-terminally reactive and binds Component I, G-34, G-17 and mini-gastrin. GPI68 which is G-17 N-terminally reactive and specific for G-17 also detects non-biologically active N-terminal fragments of gastrin, and C-terminally extended gastrin. R526 which is G-34 N-terminally reactive and is specific for G-34 and does not crossreact with G-17. All antisera bind sulphated and unsulphated forms with equimolar potency. Total gastrins were significantly lowered by the eradication of HP both basally 27.31±2.48 to 21.0±2.24 pmol/l (M±SEM) (P<0.025) and post prandially 70.32±7.52 to 38.50±4.82 (P<0.001). G-17 was significantly lowered basally 8.24±1.93 to 6.42±1.84 (P<0.01) and post prandially 52.0±7.52 to 19.6±3.67 (P<0.001). G-34 did not change significantly, basally 18.00±6.23 to 13.43±3.28 and post prandially 21.00±5.3 to 17.25±3.08 (P>0.05). Studies using gel chromatography G50 showed that there is no major contribution made from other immunoreactive fragments and that more than 90% of the circulating gastrin is G-17 and G-34° We conclude that the gastrin which is elevated in HP+ve subjects is biologically active and is predominantly due to G-17°

COMPARATIVE CHARACTERISATION OF NEUROPEPTIDE Y (NPY) FROM THE BRAIN OF THE RAINBOW TROUT (Oncorhynchusmykiss) and BROWN TROUT

(Salmo trutta).

Barton CL, Shaw C, Halton DW, Thim L*. Comparative Neuroendocrinology Research Group, Schools of Clinical Medicine and Biology & Biochemistry, The Queen's University of Belfast, Northern Ireland and *Novo Nordisk A/S, Bagsvaerd, Denmark. NPY is one of the most abundant and highly-conserved regulatory peptides in higher vertebrates. NPY immunoreactivity was found to be present in both rainbow trout and brown trout brain in comparable concentrations (520 pmol/g). Gel permeation chromatographic analysis of brain extracts from both species of trout, identified a single NPY immunoreactive peptide which coeluted with synthetic porcine NPY indicating a similar molecular mass. Semi-preparative reverse phase HPLC analysis of both trout peptides likewise resolved a single NPY immunoreactive peptide of identical retention time in each case. However, analytical reverse phase HPLC analysis indicated that rainbow trout and brown trout NPY were not of identical retention time and hence were structurally different. Plasma desorption mass spectroscopy of purified peptides confirmed this observation, deriving molecular masses for rainbow and brown trout peptides of 4313 Da and 4304 Da, respectively. Thus, NPY from two species of salmonid, until recently considered con-generic, is not structurally conserved, albeit exhibiting what may be a single substitution. These data may indicate that the primary structure of NPY in fish is not as stringently-conserved as that in higher vertebrates. This information may be a valuable asset in fish systematics.