K. Mccrea et al., 2-36[K-4,RYYSA(19-23)]PP a novel Y5-receptor preferring ligand with strongstimulatory effect on food intake, REGUL PEPT, 87(1-3), 2000, pp. 47-58
Members of the neuropeptide Y (NPY) family regulate many physiological proc
esses via interaction with at least four functional, pharmacologically dist
inct Y-receptors. However, selective antagonists developed for several subt
ypes have not been useful in defining particular Y-receptor functions in vi
vo. To identify critical residues within members of the NPY family required
for Y-receptor subtype-selectivity we have determined the contribution of
each residue within NPY to receptor binding by replacing them with L-alanin
e. In a second study, chimeric peptides where single or stretches of residu
es were interchanged between members of the NPY family were generated and r
ested in radioligand binding studies. Overall, substituted alanine analogue
s exhibited similar orders of affinities at each Y-receptor subtype with no
obvious subtype-selectivity. Residues of particular interest are Leu(30) w
hich exhibited selectivity for the Y4-receptor, whereas Asp(16) does not ap
pear to play any role in ligand binding. Several chimeric peptides, e.g., [
K-4]pancreatic polypeptide ([K-4]PP) and [RYYSA(19-23)]PP clearly showed hi
gher affinity at the Y4 and Y5 subtypes compared to the Y1 and Y2 subtypes.
in addition, the transfer of a proline residue from position 14 to 13 in p
eptide YY decreases its affinity at the Y1-, Y4- and Y5-receptors but is un
changed at the Y2 subtype. Combining these results, and with the help of mo
lecular modelling, second generation chimeras were designed. The most signi
ficant improvement was achieved in chimera 2-36[K-4,RYYSA(19-23)]PP where t
he affinity for the Y5 subtype increased by ninefold over that from NPY. Se
veral of these compounds were also tested for their ability to stimulate fo
od intake in a rat model. Interestingly, again 2-36[K-4,RYYSA(19-23)]PP sho
wed the most dramatic effect with a major increase on food intake over a ra
nge of doses compared to NPY suggesting a possible synergistic effect of se
veral Y-receptors on feeding behaviour. (C) 2000 Elsevier Science B.V. All
rights reserved.