The in-vivo effect of Lithospermum ruderale on LHRH activity in the chick

Lithospermum (LSPM) plant extracts can inhibit gonadotropin action in mammals and birds. The experiments reported in this paper were performed to note the possible effect of LSPM on the ability of LHRH to stimulate 32P testis uptake in immature chicks. LHRH injected 2 h before autopsy significantly increased 32P uptake in these animals. Water extracts of Lithospermum ruderale roots were administered subcutaneously at various concentrations and times before LHRH. LSPM injections of 2.0, 4.0, or 8.0 mg equivalents of dried material given 10 h before LHRH significantly suppressed the releasing hormone effect. 4.0 mg LSPM was not inhibitory at 16, 22, 38 or 46 h before LHRH. Interestingly, LHRH had a greater effect, as measured by 32P testis uptake, when given to these latter 3 groups then when given to controls. This suggests that LSPM may have prevented the release but not the synthesis of anterior pituitary gonadotropins.