PROLACTIN SPECIFICALLY REGULATES CITRATE OXIDATION AND M-ACONITASE OFRAT PROSTATE EPITHELIAL-CELLS

The prostate gland of many animals, including humans, produces and sec retes extremely high levels of citrate. To achieve this function, pros tate secretory epithelial cells possess unique metabolic properties th at permit accumulation and ultimate secretion (net citrate production) of citrate. Mounting evidence continues to support the concept that p rostate epithelial cells possess a limiting mitochondrial (m)-aconitas e activity that minimizes citrate oxidation and results in the accumul ation of citrate synthesized by the cells. Recent studies have reveale d that prolactin (PRL) stimulates net citrate production of rat latera l prostate (RLP). The mechanism of this PRL effect has not been establ ished. The current studies were concerned with the possibility that PR L might be involved in the regulation of citrate oxidation and m-aconi tase of prostate cells. Studies were conducted with RLP, RVP (rat vent ral prostate), RDP (rat dorsal prostate), and kidney cells. The result s showed that PRL in vitro and in vivo decreased citrate utilization a nd the level of m-aconitase in RLP cells, and conversely increased cit rate utilization and m-aconitase in RVP cells. Furthermore, PRL had no effect on either RDP or kidney cells. The effects of PRL on both citr ate utilization and m-aconitase of RLP and RVP were abolished by cyclo heximide and actinomycin. Mitochondrial studies revealed that PRL decr eased citrate oxidation of RLP and increased citrate oxidation of RVP, but had no effect on isocitrate oxidation. In conclusion, these studi es establish that PRL has a physiological role in the regulation of ci trate oxidation in prostate, and that this action is associated with P RL regulation of the biosynthesis of m-aconitase. Furthermore, the eff ects of PRL are cell-specific and targeted at m-aconitase. Copyright ( C) 1996 by W.B. Saunders Company