The distribution of histidyl-proline diketopiperazine [cyclo(His-Pro)] in discrete rat hypothalamic nuclei.
The distribution of Histidyl-Proline Diketopiperazine [cyclo(His-Pro)], a metabolite of thyrotropin-releasing hormone (TRH), was determined by specific RIA in Palkovits micropunch pools derived from discrete hypothalamic nuclei. Highest concentrations of cyclo(His-Pro) were identified in the anterior nucleus (3.5 ng/mg protein) and the paraventricular nucleus (2.95 ng/mg protein), while lower concentrations of cyclo(His-Pro) were seen in the other 6 nuclei. In contrast, TRH concentrations were highest in the ventromedial nucleus pars medialis (3.2 ng/mg protein) and arcuate nucleus (2.7 ng/mg protein). This qualitatively different distribution of cyclo(His-Pro) from that of TRH suggests that not all of cyclo(His-Pro) is derived exclusively from TRH.
Yamada
M
M
Department of Medicine, LSU Medical Center, New Orleans 70112.
Wilber
J F
JF
D000818:Animals; D007031:Hypothalamus / Q000032:analysis*; D008297:Male; D010456:Peptides, Cyclic / Q000032:analysis*; D010879:Piperazines / Q000032:analysis*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis*
D010456:Peptides, Cyclic; D010879:Piperazines; D013973:Thyrotropin-Releasing Hormone; C015924:histidyl-proline diketopiperazine