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Concentration of free and esterified cholesterol in the testes of immature and adult mice.

In the mouse, lh depletes cholesterol esters while prolactin promotes their accumulation in the testes (Bartke, 1969, 1971). In prepuberal mice, the concentration of total cholesterol in the testes has been reported to decrease (Simmons, 1969) and to increase with age (Ichihara, 1969). After weaning, the concentration of total cholesterol has been reported to remain approximately the same until the age of 90 days (Simmons, 1969) or to increase more than twofold between the ages of 42 and 49 days (Ichihara, 1969). No information is available on the amounts of free and esterified cholesterol in the testes of immature mice. The concentration of esterified and free cholesterol in the testes of mice between the ages of 5 and 120 days has, therefore, been studied. Random-bred mice derived from crossing YS/ChWf, YS/ChWf-dw and Dw/Wf strains were mated after 2 months of age and, thereafter, kept in pairs. The litters were weaned at the age of 21 to 23 days. Animals were killed by cervical dislocation and the concentration of free and esterified cholesterol was measured as previously described (Bartke, 1969). In mice less than 3 weeks old, the testes from two to eight animals were used for each determination. For statistical calculations and presentation, the results were pooled into nine groups. Within each group, there were no differences in the concentration of esterified or free cholesterol due to age. As seen from the data presented in Table 1, the concentration of cholesterol esters increased gradually from 5 to 19 days of age, fell slightly (P<0-05) after weaning and then rose abruptly (P<0-01) to reach maximum values in mice 31 to 44 days old. Thereafter, it gradually declined. The concentration of free cholesterol apparently increased until the animals were 12 days old, then decreased and remained low until 44 days of age. It was increased (P<0-01) in young adult males (50to 83-day-old) and again lower (P<0-01) in mice 105 to 120 days of age. In the animals studied, regardless of age, a majority of cholesterol (74 to 89%) was present in the free form. Consequently, the changes in the concentration of total cholesterol, with few exceptions, followed the changes in the concentration of free cholesterol. The percentage of esterified cholesterol increased in suckling mice between 7 and 19 days of age (P<0-01), remained unchanged for several days after weaning and then rose to 25-9% in 31to 44-day-old animals (P<0-01). It