Further studies on the effect of cyclic nucleotides on testis DNA synthesis.

The inhibitory effect of dibutyryl cyclic AMP (dbcAPM) on in vitro rat testis DNA synthesis appears to be relatively specific in nature. Of 7 organs studied, only testis and kidney in vitro DNA synthesis was significantly affected. In addition, another cyclic nucleotide, dibutyryl cyclic GMP (by dbc AMP), had no effect on in vitro testis DNA synthesis. This was true whether testis tissue was mature or immature. Similarly, by dbcAMP had no significant effect on in vitro testicular protein or RNA synthesis. The inhibition of in vitro testicular DNA synthesis by dbcAMP occurs while 3H-cAMP is accumulating in testis tissue. dbcGMP was found to have no antagonistic effect towards the inhibitory effect of dbcAMP on in vitro testis DNA synthesis.