Sequential androgen blockade: a biological study in the inhibition of prostatic growth.

We attempted to determine the effects of the combination of a 5-alpha reductase inhibitor and an antiandrogen on rat ventral prostate and seminal vesicle weight. We also attempted to determine whether the prostatic cell death gene TRPM-2 would be expressed using this combination of drugs. Adult male Sprague-Dawley rats were randomly assigned to 7 groups of 15 animals. Four groups served as controls: an intact group sacrificed at the initiation of the trial (group 1), a castrate control group (group 2), an intact control group (group 3), and a group treated with the combination of an LHRH agonist plus antiandrogen (group 7). Three other groups were treated with daily subcutaneous injections of 5 alpha reductase inhibitor (group 5), a nonsteroidal pure antiandrogen (group 4) or both (group 6). After 5 days of treatment 5 animals in each group were sacrificed and prostatic tissue was assayed for the androgen repressed prostatic cell death gene TRPM-2. At 30 days (35 days for group 7) the remaining animals were sacrificed and their ventral prostates, seminal vesicles, and testes (except group 3) were weighed. The combination group (group 6) had a significantly lower prostate weight than either of the monotherapy groups (4, 5), or intact control groups, was equivalent to group 7 but was significantly heavier than the castrate group 2. The seminal vesicle weights of the combination group 6 were significantly lower than the monotherapy groups (4, 5), intact control group, castrate group (3) and was equivalent to group 7. Only castration was able to induce expression of the cell death gene TRPM-2. In this model, the combination of 5 alpha reductase inhibitor and an antiandrogen is as effective a mode of androgen ablation as combination therapy of LHRH agonist plus antiandrogen. Clinically, this combination may translate into adequate androgen blockade without impotence or other side effects of testosterone deprivation. Clinical trials appear warranted to assess this hypothesis.     

Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment

The antenatal variant of Bartter's syndrome is an autosomal recessive kidney disease characterized by polyhydramnios, premature delivery, hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous, having been linked recently to mutations in an ATP- sensitive, renal outer medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl co-transporter, NKCC2. We characterized four of the mutations reported in three heterozygous ROMK variants of antenatal Bartter's and found that each expressed a distinct phenotype in Sf9 cells. One mutation expressed normal function and appears to be an allelic polymorphism. The other three mutations produced channels with significantly reduced K+fluxes. However, the mechanisms in each case were different and reflected abnormalities in phosphorylation, proteolytic processing or protein trafficking. The different mechanisms may be important in the design of appropriate therapy for patients with this disease.      

The effect of the chronic administration of a potent luteinizing hormone releasing hormone analog on the rat prostate

In order to assess the effect of the chronic administration of a potent luteinizing hormone releasing hormone analog, (D-SER(But)6) LHRH (1-9) nonapeptide-ethylamide (Buserelin, HOE 766) on the pituitary gonadal axis, and the prostate, adult male Wistar rats were administered either 0, 3, 10 or 50 micrograms./kg. body weight Buserelin subcutaneously daily. At 7, 21, 35 and 42 days of treatment, groups of animals were sacrificed and certain serum endocrine and grave metric parameters determined. In addition, at 1, 21 and 42 days of treatment the 1-hour response of serum LH and serum testosterone to a single injection of 10 micrograms./kg. body weight Buserelin was determined. All treatment doses had similar effects. Serum prolactin and the basal and "acute" response of serum LH to Buserelin (+ delta 5,000 per cent) were unaltered throughout treatment. Testes weight, testicular LH receptor content, and basal and "acute" concentrations of serum testosterone were markedly decreased by 42 days of treatment (48, 89, 88 and 88 per cent, respectively). Although seminal vesicle weight declined 50 per cent at 42 days of treatment, prostate weight was not altered from initial weight, but was significantly lower than age matched control at 42 days of treatment. Buserelin remains a potent stimulator of pituitary LH release even during chronic administration. It markedly reduces serum testosterone through a predominant testicular site of action. Buserelin treatment inhibits the growth of the normal prostate, but does not cause its regression.