STUDIES OF THE GONADOTROPIC ACTIVITY IN THE LACERTILIAN PITUITARY

Abstract

Pituitary gonadotropic activity in the male spinytai l ed lizard, Uromastix hardwicki, was studied using in vitro androgen prod uction by h omologous testicular tissue . Ovine L11 (NIAf\1f\!D -o LlI- 22) was used as a reference prepaTatiol1. Minced testicular tissue from adult lizards, was incubated ",ith serial diJutions of LlI or pituitary ext r act, LH W 0 sus e din ado s era n g e 0 [ 4 - 1 6 n g and the pituitary extract at concentrations representing 10-40 ug of fresh pituitary tissue. Androgen produced was measured by ralioimmunoossay in the tissue as ",ell as In the incubation medium. L11 Clncl pi tu i tary ext racts i n the dose range us e d, eliritpri a linear log dose response relationship. Li zard gonadotropin (LCn ) octivity is reported in terms of the standard. The method enabled us to compare gonadotropic activity of pituitary glands [rom immature and adult li zards and adult li za rd s majntaj ned at different envi ron mental temperatures. Immature li zard s showed a s ignificantly iii lower gonadotropic activi ty LIS compared to the adu1 t animals . When gonadotropic activities of animals maintained o 0 at 18 C and 28 C were c omp are d, a significant decreasr in the gonadotropic activity Ivas observed in the temperature primed gro up . Effect of t emperature on the respon s iveness of th e testicular tissue wa s als o demonstrated. An arti f icial increase in the envir onmental te mp e r a ture (28 o C) rendered the testi c ul ar tissue several tjmes more sensitive to gonaLlotropins than the testicul ar ti ssue from anima l s kept at room t e mp erature (lSoC). The incrcClsc in temperature also induced a significant increase in tl f' testicular weight and plasma androgens.