"As a process to study the mechanism of steroid hormones at the molecular level,the activities of lactic dehydrogenase (L.D.) and malic dehydrogenase (M.D.),NAD-linked transhydrogenases, were measured in the testis and the prostate. Ahundred male rabbits were divided into ten group as follows: Group 1: Control Group 2: Estrogen (6,000 units) injected Group 3: Androgen (1,200 unite)injected Group 4: Progesterone (1,200 units) injected Group 5: Hydrocortisone(30 mg) injected Group 6: DOCA (6 mg) injected Group 7: Castration control Group8: Castration and estrogen (6, OOO units) injected Group 9: Castration and androgen (1,200 units) injected Group 10: Castration and progesterone (1,200units) injected Changes in the activities of lactic dehydrogenase and malic dehydrogenase in theorganic tissues by exogenous steroid hormones were carefullyobserved. The lactic dehydrogenase activities were measured by the method of Wroblewski and La Due, and malic dehydrogenase activities by the Bodansky`s modification of Porter`s method. The results are as follows: 1) The control valueof L.D. activities in the testicular tissue of normal rabbits proved to be 89,400units per ram. The L.D. activities showed an increase up to 110.4 per cent in theestrogen injected group, 179.3 per cent in the androgen injected group and 147.0 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 85.2 per cent and 81.5 per cent, respectively. 2) The control value of M.D. activities in the testicular tissue of the normal rabbits was 23,600 units per gram. The M.D. activities showed an increase upto 111.4 per cent in the estrogen injected group. 191.1 per cent in the androgen injected group, and 156.8 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 85.2 per cent and 81.5 per cent, respectively. 3) In the prostate tissues of non-castrated rabbits, the L.D. activities were estimated normally to be 48,100 units per gram. The administration of sex hormone resulted in raising the activities upto 101.8 per cent in the estrogen injected group, 196.9 per cent in the androgen injected group and 153.9 per cent in the progesterone injected group. But the administration of hydrocortisone and DOCA decreased the value down to 92.5 per cent and 97.1 per cent, respectively. 4) In the prostate tissue of non-castrated rabbits, the control value of M.D. activities proved to be 14,600 unite per gram. The M.D. activities showed an increase upto 117.8 per cent in the estrogen injected group, 206.8 per cent in the androgen injected group and, 176.7 per cent in the progesterone injected group, while the administration of hydrocortisone and DOCA decreased the value down to 81.9 per cent and 95.2 per cent, respectively. 5) The prostatic L.D. activities were decreased to half the normal two weeks after castration. The administration of sex hormones (i.e., estrogen, androgen and progesterone) acted inclusively upon elevating the level f activities. Androgen, in general, was the most effective to restore the activity to the level of pre-castrated state. 6) The prostatic M.D. activities were also decreased to half the normal two weeks after castration. The administration of sex hormones acted inclusively upon elevating the level ofthe activities. Androgen had a remarkable effect in elevating the M.D. activities, which showed twice the precastration level. In this study, it is concluded that L.D. and M.D. activities are present in the testis and the prostate. They are induced and activated by the administration of sex hormones, of which androgen has the most remarkable effect, and estrogen and progesteronehave less effect, while hydrocortisone and DOCA are ineffective in some cases orinhibitory in others.
Key Word : lactic and malic dehydrogenase activity"
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