Effects of hypothamic hyperphasia on weights of muscle, bone, viscera and fat in chickens
2007
Nikki, T.(Kyushu Tokai Univ., Minamiaso, Kumamoto (Japan). School of Agriculture) | Okano, N. | Shibata, T. | Nobukuni, K.
Experiments were performed to investigate the effects of hypothalamic hyperphasia on weights of muscle, bone, viscera and fat, relating to androgen deficiency that might occur with hypothalamic lesions. Male chickens (White Leghorn, Shever strain) were divided into the following 3 groups at 180-days-old : hypothalamic lesion ; sham operation ; and control. Hypothalamic lesion was formed electrolytically using a stereotaxic instrument at 187- to 190-days-old, aiming at the Nuc. inferioris hypothalami (IH). A certain number of lesioned birds were with injected testosterone propionate (TP ; 1 mg/bird) subcutaneously once every 2 days from 201days-old. Birds in each group were sacrificed by decapitation at 246- to 250-days-old. Chickens with lesion at the ventral half of the nucleus IH and antero-dorsal part of the Eminentia mediana (ME) showed large and slight marked increases, respectively, in body weight and feed consumption with typical signs of hypothalamic hyperphasia, indicating that the satiety center is located in the ventral half of the nucleus IH. These birds also displayed prominent decline of testes and wattles, suggesting androgen deficiency. However, TP injection to hyperphasic birds could not arrest increases in body weight or feed consumption. In hyperphasic birds without TP injection, both weights of muscle and bone decreased and fat weight alone increased compared with sham-operated and control birds. In hyperphasic birds with TP injection, weights of muscle, bone and fat approached the level of sham-operated and control birds, differing significantly from those in birds without TP injection. Viscera weighed the same in hyperphasic, sham-operated and control birds, regardless of injection with or without TP. The increase in body weight caused by hypothalamic hyperphasia is thus assumed to depend on the increase in fat weight, and augmentation of fat would be accelerated not only by hyperphasia, but also by androgen deficiency that might be present as a result of the hypothalamic lesion.
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