Androgen Interaction with the Polyamine System of the Rat Prostate

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Abstract
The ventral and dorsal lobes of the rat prostate contain larger quantities of the aliphatic amines putrescine, spermidine and spermine and higher activities of the enzyme ornithine decarboxylase (ODC; EC 4.1.1.17) than other accessory sex glands. In contrast, the coagulating gland and the seminal vesicles contain only small quantities of the amines but the highest activities of the glands (ARG; EC 3.5.3.1). Lineweaver-Burk plots indicated that the Km-value for ARG in the coagulating gland and ODC in the ventral prostate lobe were 20 mM and 0.2 mm, respectively. Castration decreased ODC and ARG activities to 3 and 505 of control levels respectively, after 3 days, whilst the Km-value were unaffected daily administration of 3 mg dihydrotesterone (DHT) prevented these castrational changes. Oestrogen treatment alone had no effect on the activities of the enzymes, but appeared exert a synergistic effect with androgen on the ODC, which was mirrored by an increase in the level of putrescine in the tissue. The data suggest that androgen control of the polyamine pathway is biphasic, first stimulatory and later inhibitory with lesions occurring at the ODC, possibly via short loop feedback of its product putrescine, but also at subsequent enzymic steps in spermidine and spermine biosynthesis.
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