Effects of growth hormone and prolactin on testicular macrophages in long-term hypophysectomized rats

Long-term hypophysectomized (LTHX) rats were treated for 1 week with growth hormone (rGH, 600 micrograms/kg body wt.), prolactin (rPRL, 600 micrograms/kg body wt.), combined rGH/rPRL or vehicle, to study the effects of these hormones on testicular macrophages. Growth hormone and, to a lesser extent, prolactin significantly increased the number and size of testicular macrophages. The in vivo phagocytic capacity of testicular macrophages was tested by their ability to clear the testicular interstitium of dead Leydig cells after treatment with the specific cytotoxic reagent ethylene dimethane sulphonate (EDS). In vehicle- or rPRL-treated rats, abundant EDS-killed Leydig cells (about 50% of the pre-existent population) remained in the testicular interstitium 72 h after EDS treatment, whereas clearance of the testicular interstitium of dead Leydig cells was largely achieved in rGH- or rGH/rPRL-treated rats. These results indicate that growth hormone and prolactin have stimulatory effects on testicular macrophages in LTHX rats.