Hypothalamic regulation of histidyl-proline diketopiperazine binding sites in the rat liver.
The effects of hypothalamic hormones and electrolytic lesioning of the ventromedial hypothalamic nuclei (VMH) on histidyl-proline diketopiperazine (cyclo(His-Pro] binding in the rat liver were studied. VMH-lesioning markedly decreased cyclo(His-Pro) binding in the liver. Scatchard analysis revealed that the loss of cyclo(His-Pro) binding induced by VMH lesioning was due to a decrease in the number and affinity of binding sites. Somatostatin (SS) administration decreased cyclo(His-Pro) binding. The SS-induced changes in cyclo(His-Pro) binding were due to changes in the binding affinity. On the other hand, the administration of TRH or LH-RH did not affect cyclo(His-Pro) binding in the liver, although cyclo(His-Pro) has been proposed to be a metabolite of TRH. These findings suggest that the hypothalamus may regulate the cyclo(His-Pro) binding sites in the liver probably by controlling pancreatic SS secretion, since a VMH-lesion is reported to cause hypersecretion of pancreatic SS.
Ogawa
N
N
Department of Neurochemistry, Okayama University Medical School, Japan.
Sora
Y H
YH
Saito
M
M
Shimazu
T
T
D000818:Animals; D007028:Hypothalamic Hormones / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010456:Peptides, Cyclic / Q000378:metabolism*; D010879:Piperazines / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014697:Ventromedial Hypothalamic Nucleus / Q000378:metabolism*
D007028:Hypothalamic Hormones; D010456:Peptides, Cyclic; D010879:Piperazines; C015924:histidyl-proline diketopiperazine