Effect of catecholamines on ornithin decarboxylase activity in the testis of immature rat

Abstract

Intratesticular injection of epinephrine and norepinephrine caused stimulation of ornithine decarboxylase (ODC) activity in the testis of immature rat. The effect of epinephrine was time and dose dependant. The minimal effective dose for epinephrine was found to be 100 pg and optimal stimulation was observed with 500 ng of the drug. Maximal stimulation of ODC occurred at 2 h after the treatment and reduced significantly at 4 h reaching to control levels at 6 h. Simultaneous injection of epinephrine with dibutyryl cAMP, luteinizing hormone, follicle stimulating hormone or prostaglandin E₂ caused additional stimulation of the enzyme activity. Injection of epinephrine to norepinephrine treated animals caused additional effect. Both epinephrine and norepinephrine were found to stimulate the enzyme activity in leydig cell and seminiferous tubule fractions. These results suggest that catecholamines are also involved in the regulation of ODC activity in the testis of rat.