THE EFFECTS OF PROTEIN-CALORIE MALNUTRITION AND CHLOROQUINE THERAPY ON THE CONJUGATION OF OESTRADIOL-178 BY THE RAT LIVER

Abstract

The conjugation of 14e-oestradiol-l7 β by rat liver homogenates was studied using a modified version of Boo and Breuer’s method (1969). This consists of incubating the homogenates with cofactors at 37°C for four hours and extracting the free steroid radioactivity both before and after hot acid hydrolysis for the evaluation of the extent of conjugation based on the formulae: (i, Free steroid counts x 100 Free + conjugated steroid counts 1 (ii) Free steroid counts x 100 Total radioactive steroid 1 counts added Each experiment was corrected for its own recovery. The method was evaluated for accuracy, precision, sensitivity and specificity. It was observed that ordinary water as well as denatured rat liver homogenates exhibited negligibly low conjugation. The method was then applied to study steroid conjugation in the following experimental rats:- (a) Protein-calorie malnourished rats. (b) Rats injected intramuscularly with single 8.0mg doses of chloroquine phosphate. (c) Rats injected intramuscularly with multiple (nine) 8.0mg doses of chloroquine phosphate. (d) Protein-calorie malnourished rats which were terminally injected with single 8.0mg doses of chloroquine phosphate intramuscularly. (e, Rats that were injected (i.m.) with four daily doses each of 10µg of non-radioactive oestradiol-17 β. (f) Rats injected (i.m.) simultaneously with chloroquine phosphate (8.0mg) and non-radioactive oestradiol-17BS (four days). (g) Rats injected (i.m.) with 10µg non-radioactive oestradiol-17 β (four days) followed by chloroquine phosphate 8.0mg (four days). (h) Rats that were deprived of food and water for four days. The test results were compared with control results in the various experimental groups and the following observations made:- (i) Protein-calorie malnutrition decreased the conjugation of 14C-oestradiol-17 β the rat liver homogenates (P <.0 5). (ii) Both single and multiple doses of chloroquine phosphate increased this conjugation (P<0.001, P ( 0 5 respectively). (iii) Chloroquine phosphate decreased the conjugation in protein-calorie malnourished rats (P <0.01). (iv) Non-radioactive oestradiol-17 β only decreased the conjugation (P< 0.01). (v) Non-radioactive oestradiol-17 β and chloroquine phosphate (given simultaneously) decreased the conjugation significantly (P <0.001). (vi) Injection of non-radioactive oestradiol-17B followed by chloroquine phosphate had no effect on the conjugation (P > 0.5). (vii) Complete starvation had no effect on the conjugation of l4C- oestradiol-17 β > by the rat liver (P 0.5). It was observed that there were no sex or interlobar differences in the conjugation of oestradiol-17β. Chloroquine phosphate was shown to have no in vitro effect on the conjugation phenomenon, implying that the effects of chloroquine phosphate observed are biological. It is suggested that chloroquine might be forming a biochemical complex with oestradiol-17B and that this complex might exhibit inhibitory actions on the hepatic metabolism of oestradiol-17β.