THE EFFECT OF BORON SUPPLEMENTATION ON THE DISTRIBUTION OF BORON IN SELECTED TISSUES AND ON TESTOSTERONE SYNTHESIS IN RATS

Boron has been shown to increase the concentration of oestrogen and te stosterone in plasma. The aim of this study was to investigate further the effect of boron by determining the response to three levels of bo ron intake during an experimental period of 6 weeks. The concentration of plasma testosterone and its production in the testes were determin ed in addition to the distribution of boron in selected tissues. Boron was added to the drinking water as boric acid to provide 2, 12.5, and 25 mg boron/rat/d. Body weight gain was found to be higher at the low est dose but no significant change was observed at the highest dose. T he distribution of boron in all tissues reflected its level of intake with all tissues demonstrating an increase over time. Within 6 weeks, rats fed the lowest and intermediate doses appeared to have a favorabl e effect on the indices examined, whereas the toxic testicular effects indicated by significant increases in the plasma follicle stimulating hormone concentration and testicular atrophy was associated with the higher dose (25 mg). The synthesis of testosterone by the testicular h omogenates in vitro from its immediate precursor androstenedione in th e presence of boron was determined but there did not appear to be any clear relationship between dietary boron and testosterone production i n vitro. The effect of boron on steroidogenesis and testicular functio n and development appears to be proportional to the dose and subsequen t boron concentration in the testes.