Influence of luteinizing hormone and adenosine 3′:5′-cyclic monophosphate on the metabolism of free and esterified cholesterol in mouse Leydig-cell tumours

Abstract

1. Male C57B1/6J mice bearing Leydig-cell tumours known to synthesize steroids in response to luteinizing hormone (LH) were given intravenous injections of [1,2-(3)H]cholesterol (50-100muCi per animal). Single-cell suspensions were prepared from the tumours 5-9 days after the injection of [(3)H]cholesterol and were incubated at 37 degrees C in foetal calf serum supplemented with 50mm-Tris-HCl, pH7.4. At various times after the start of incubation cells were collected by filtration of portions of the suspension and their sterols analysed. Within 10min after LH (5mug/ml) or 3':5'-cyclic AMP (20mm) was added to the cell suspensions an increased conversion of ester cholesterol into free cholesterol could be demonstrated. 2. To observe this rapid effect of LH it was necessary to incubate the cells for 60min before addition of hormone. 3. The specific radioactivity of testosterone produced was approximately equal to that of the intracellular cholesterol regardless of the presence or absence of LH. 4. The amount of free cholesterol produced in response to LH was far greater than that needed for steroid synthesis. 5. Free cholesterol, but not esterified cholesterol, was released into the incubation medium linearly with time and this release was unaffected by LH. LH may stimulate steroidogenesis in part by increasing the concentration of free cholesterol within the cell.

The Bovine Testes-II: Role of Hormones During Pre and Post Natal Development

“…Leydig cells (Samuels and Eik-Nes, 1968). Conversion of cholesterol esters into cholesterol takes place in lipid droplets which, then, is carried to mitochondria for conversion into 20-, 22R dyhydroxycholesterol and the removal of side chain here, results in the production of pregnenolone (Moyle et al, 1973). Rest of the steps of pregnenolone conversion into testosterone takes place in the smooth endoplasmic reticulum (Bun-Ichi, 1973;Shikita and Tamaoki, 1965).…”

Concentrations of Free and Esterified Cholesterol in the Testes of Maturing Rabbits

“…Courot (1971) reported a 10-to 15-fold increase in LH during the prepubertal period in the lamb. Bartke (1971a) and others (Herbst, 1967;Behrman & Armstrong, 1969;Behrman, Armstrong & Greep, 1970;Behrman, Moudgal & Greep, 1971; Moyle, Jungas & Greep, 1973a) have postulated a direct rôle for LH in regu¬ lating cholesterol and cholesterol ester metabolism in the gonads of various species. While it is well established that cholesterol is the major precursor molecule in steroid biosynthesis (Strickland, Nayfeh & French, 1970) (Davis, Bridges & Coniglio, 1966;Oshima & Carpenter, 1968;Ichihara, 1969;Simmons, 1969;Bartke, 1971b (Davis et al, 1966;Oshima & Carpenter, 1968) have reported little or no change in these levels with maturation of rat testes.…”