PT  - JOURNAL ARTICLE
AU  - M G Luquita
AU  - V A Catania
AU  - E J Sánchez-Pozzi
AU  - A D Mottino
TI  - Ovine prolactin increases hepatic UDP-glucuronosyltransferase activity in ovariectomized rats.
DP  - 1996 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 921--925
VI  - 278
IP  - 2
4099  - http://jpet.aspetjournals.org/content/278/2/921.short
4100  - http://jpet.aspetjournals.org/content/278/2/921.full
SO  - J Pharmacol Exp Ther1996 Aug 01; 278
AB  - The potential role of prolactin in modulating hepatic UDP- glucuronosyltransferase (UGT) activity was studied. Ovariectomized adult female rats were treated with ovine prolactin (oPRL) at doses of 150, 200, 260, and 310 micrograms/100 g b.wt. per day, for 4 days. Enzyme assays were performed in native and activated microsomes with p-nitrophenol as substrate. Activation was achieved either by including UDP-N-acetylglucosamine in the incubation mixtures or by preincubating native microsomes with palmitoyl-lysophosphatidylcholine. Data obtained with UDP-N-acetylglucosamine as activator showed that increasing doses of oPRL produced a progressive increase in enzyme activity up to a maximum of about 35% over basal values. Immunoblotting of microsomal protein with anti-UGT antiserum revealed also a dose-dependent increase in the immunoreactive protein. A kinetic method for measuring glucuronidating enzyme content confirmed the result of the immunoblot. oPRL induced minor changes in the physicochemical properties of the microsomal membrane. Consistent with this observation, studies performed with palmitoyl-lysophosphatidylcholine as activator showed no change in UGT latency, suggesting that the functional characteristics of the enzyme were not substantially affected by oPRL. The current data support the conclusion that prolactin may act as a modulator of UGT activity by increasing the amount of enzyme.