Effects ofCo gamma-ray local irradiation on the level of testis tissue cyclic nucleotides and plasma testosterone in the rat.

This study was designed to investigate the levels of testis tissue cyclic nucleotides and plasma testosterone in testis-irradiated rats with saturation analysis 1-52 days after 676 rad and 7 days after 290-1930 rad. It was found that ionizing radiation of a given dose scale did not affect significantly the excretion of testosterone. An initial rise of cyclic adenosine monophosphate (cAMP) was probably associated with an increase of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) excretion and a decrease of cAMP in the later stage was possibly due to the depletion of the germ cells, following irradiation less than 965 rad. The reduction of cAMP after 1930 rad was probably related to direct inhibition of the larger dose of cAMP production. These results suggest that the levels of cAMP after irradiation can reflect the degree of testis radiation injury. In addition, it was also found that ionizing radiation failed to change the testis cyclic guanosine monophosphate (cGMP) levels, suggesting the presence in testis of only a 'one-way' regulation carried out by cAMP. [ABSTRACT FROM AUTHOR]