Paracrine role of testicular macrophages in control of Leydig cell activities in the wall lizard, Hemidactylus flaviviridis.

The present in vitro study in wall lizards Hemidactylus flaviviridis demonstrates the differential paracrine role of testicular macrophages in regulation of Leydig cell activities under normal physiological and inflammatory condition for the first time in reptiles. To accomplish the objective, the effect of condition media of testicular macrophages incubated in medium alone or with FSH/LPS was observed on Leydig cell steroidogenesis and proliferation. Non-activated testicular macrophage-conditioned medium (TMCM) increased the testosterone production from Leydig cells and the stimulation was more pronounced with FSH-preactivated TMCM, suggesting the trophic effect of FSH on secretion of steroidogenic factor from lizard testicular macrophages. Also, testicular macrophage-secreted paracrine factor had additive effect on FSH-induced testosterone production, since FSH-activated TMCM that contained both FSH as well as FSH-induced testicular macrophage-secreted paracrine factor, stimulated the Leydig cell steroidogenesis more potently than FSH alone. In contrast, LPS-activated TMCM inhibited the testosterone production suggesting the inhibitory role for testicular macrophages in control of Leydig cell steroidogenesis under inflammatory condition. Like steroidogenesis, the differential effects of TMCM were observed on Leydig cell proliferation depending on normal or inflammatory condition. Non-activated TMCM increased, while LPS-activated TMCM decreased the FSH-induced Leydig cell proliferation. It appears that lizard testicular macrophages under inflammatory condition secrete a different paracrine factor which instead of stimulating inhibits Leydig cell activities.