Pro-TRH-connecting peptides in the rat pancreas during ontogenesis.
Rat thyrotropin-releasing hormone prohormone (pro-TRH) is a protein containing five copies of TRH, separated by connecting peptides. We have recently developed radioimmunoassays to synthetic peptides corresponding to prepro-TRH(160-169) and prepro-TRH(178-199). In the present study we have used these assays to investigate the ontogenesis of pro-TRH-derived peptides in the rat pancreas. Reverse-phase HPLC analysis of pancreatic extracts from 2-day-old rats showed the presence of two major immunoreactive peptides exhibiting the same retention time as synthetic prepro-TRH(160-169) and prepro-TRH(178-199), respectively. The concentrations of TRH and pro-TRH cryptic peptides in the rat pancreas rose rapidly after birth, reached a maximum at day 2-4 and decreased gradually afterwards. Streptozotocin treatment of newborn rats induced a marked decrease of TRH (96%), prepro-TRH(160-169) (97%) and prepro-TRH(178-199) content (94%) in pancreatic extracts. These results indicate that the evolution of TRH and pro-TRH-derived peptides follows the same pattern during the postnatal period. Our results also suggest that beta-cells are the only source of pro-TRH-derived peptides in the rat pancreas.
Dutour
A
A
Laboratoire de Neuroendocrinologie Expérimentale, INSERM U. 297, Faculté de Médecine Nord, Marseille, France.
Bulant
M
M
Giraud
P
P
Nicolas
P
P
Vaudry
H
H
Oliver
C
C
D000375:Aging; D000595:Amino Acid Sequence; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D005333:Fetus; D007328:Insulin / Q000032:analysis; D008969:Molecular Sequence Data; D010179:Pancreas / Q000254:growth & development*; D010455:Peptides / Q000138:chemical synthesis; D011498:Protein Precursors / Q000032:analysis* / Q000235:genetics; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis* / Q000235:genetics
D007328:Insulin; D010455:Peptides; D011498:Protein Precursors; D013973:Thyrotropin-Releasing Hormone; C046418:pro-thyrotropin releasing hormone; D011761:Pyrrolidonecarboxylic Acid