EFFECT OF FAT-FREE DIET ON ENZYME ACTIVITIES OF RAT TESTES

1. Particulate fractions of rat testes obtained by ultracentrifugation were studied for their succinic acid dehydrogenase (SDH) and lactate dehydrogenase (LDH) (isoenzymic) activities. The maximal succinic acid dehydrogenase activity was found localized to mitochondrial subfraction D by ultracentrifugation, but the LDHx isoenzyme was preferentially localized to testicular mitochondrial subfraction E. These findings support the view of a particulate binding or localization of the above-mentioned two enzymes in testes. 2. In rats fed a diet deficient in essential fatty acids (EFA) the clinical symptoms of this deficiency, manifest as hypospermia or aspermia, were associated with a statistically significant increase in C16, C18 and C18:1 fatty acids and a decrease in C18:2 and C18:3 fatty acids. 3. A statistically significant decrease in SDH and LDHx activities was shown to be induced by the deficiency. However, the total LDH activity (including that of all six isoenzymes of LDH in testes) was significantly increased. 4. The enzymio changes described are consistent with the idea that EFA, present in particulate fractions, may play a part in the biological (catalytic) function of these fractions. 5. It is suggested that estimation of SDH and LDHx activities of testes may be used as an index of the degree of deficiency in EFA. © 1969 Dr. Dietrich Steinkopff Verlag.