Effects of dexamethasone on TRH and TRH precursor peptide (Lys-Arg-Gln-His-Pro-Gly-Arg-Arg) levels in various rat organs.
The effect of an acute dexamethasone administration on thyrotropin-releasing hormone (TRH) and TRH precursor peptide (Lys-Arg-Gln-His-Pro-Gly-Arg-Arg) (p-8) levels in various rat organs has been studied. Rats were injected i.p. with 25 micrograms of dexamethasone/100 g body weight (group A), 500 micrograms of dexamethasone/100 g body weight (group B) or saline (group C). The rats were serially decapitated after the injection. TRH and p-8 levels in the hypothalamus, cerebrum, cerebellum and brain stem, stomach and eye and plasma TRH and thyrotropin (TSH) levels were measured by individual radioimmunoassays. P-8 levels in the hypothalamus decreased significantly in both group A and B at 1-4 hours after the injection, and then returned to pretreated levels at 24 hours after the injection. TRH levels in the hypothalamus increased significantly in both group A and group B at 1-4 hours after dexamethasone injection. No changes in p-8 and TRH levels were observed in other organs. In group A, plasma TRH levels tended to decrease at 1-2 hours, then to increase at 3 hours. In group B, plasma TRH levels decreased 1-4 hours after the dexamethasone injection, then increased at 24 hours. The plasma TSH levels decreased significantly at 1-4 hours in group A and group B, returned to pretreatment levels at 24 hours in group A, and increased significantly in group B at 24 hours after dexamethasone injection.(ABSTRACT TRUNCATED AT 250 WORDS)
Mitsuma
T
T
Fourth Department of Internal Medicine, Aichi Medical University, Japan.
Hirooka
Y
Y
Nogimori
T
T
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001933:Brain Stem / Q000737:chemistry* / Q000378:metabolism; D002531:Cerebellum / Q000737:chemistry* / Q000378:metabolism; D002850:Chromatography, Gel; D003907:Dexamethasone / Q000494:pharmacology*; D005123:Eye / Q000737:chemistry / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D007031:Hypothalamus / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D013270:Stomach / Q000737:chemistry; D013972:Thyrotropin / Q000032:analysis; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis* / Q000097:blood / Q000378:metabolism
D000596:Amino Acids; D011498:Protein Precursors; D013973:Thyrotropin-Releasing Hormone; D003907:Dexamethasone; D013972:Thyrotropin