Formation of ester forms of riboflavin in the pituitary gland of rat.
We studied the formation of ester forms of riboflavin in the pituitary gland of rats using 14C-riboflavin labeling and a gel filtration technique. The active formation of ester fraction of riboflavin suggests that two synthesizing enzymes of ester forms, flavokinase and FAD pyrophosphorylase, exist in this organ. A minor peak containing a lesser amount of radioactivity contained protein as measured by UV absorption at 280 nm was found when supernatant from incubated homogenate was chromatographed on a Sephadex G-15 column. This suggests the presence of a riboflavin-binding protein; the amount of 14C-riboflavin bound to pituitary proteins was expressed as the binding capacity of riboflavin. No changes were found in the binding capacity or esterification of riboflavin in the pituitary gland of rats treated with ACTH, dexamethasone phosphate, or subjected to liver impairment by CC14 injection. However, esterification was increased at 24 and 48 h after adrenalectomy. We posit that the riboflavin turnover in the pituitary gland may not be subject to marked changes in order to maintain the function of this organ. In aged rats, esterification was lower than in young rats suggesting that the turnover of pituitary riboflavin is related to senescent phenomena.
D000315:Adrenalectomy; D000818:Animals; D002850:Chromatography, Gel; D004951:Esterification; D066298:In Vitro Techniques; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains; D012256:Riboflavin / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
D012256:Riboflavin