The use of pigs as an animal model to evaluate the efficacy, potency and specificity of two growth hormone releasing factor analogues.

In 1982, Guillemin et al reported the isolation of the human (h) growth hormone (GH) releasing factor (GRF) from a pancreatic tumour in an acromegalic patient. Since then, work to develop potent GRF analogues has been widespread and the rat has been the main animal model used. The aim of the present study was to compare the efficacy, potency and specificity of two GRF analogues with those of the native GRF(1-29)NH(2)using pig (p) as the animal model. Two analogues, Al ([His(1), D-Ala(2), Ala(8,9,15,17), D-Arg(29)] hGRF(1-29)NH(2)) and A2 ([D-Ala(2), Ala(8,9,15,17), D-Arg(29)] hGRF(1-29)NH(2)) were compared with the h or pGRF(1-29)NH(2). Five studies were designed using 28-48 kg BW growing barrows. Results showed that the two GRF analogues were more potent than the native GRF molecule, were highly specific, were active for long periods of time and were able to induce changes in body composition similar to those reported with GH or other GRF analogues. Because of the similarity between swine and human species with respect to the amino acid sequence of GRF and to the physiology, secretion and effects of GH, it can be proposed that the pig could be used as a pre-clinical animal model to study and test new GRF molecules over short and long periods of time.