Inhibitory Effects of Melatonin, Prostaglandin E1, Cyclic Amp, Dibutyrylcyclic AMP and Theophylline on Rat Seminiferous Tubular Contractility in vitro

Publisher Website
Google Scholar
Abstract
Autorhythmic contractions (frequency) of seminiferous tubules from adult male rats responded biphasically to PGE1 in vitro. At low concentrations (10-9 M), the frequency increased, but at higher concentrations (10-7 or 10-8 M), the rate of contractions was diminished. Depth or intensity of tubular contractions showed a similar trend with a decreased magnitude at 10-6 M. Tonus of the tubules was increased at 10-9 M concentration of PGE1, but not at higher concentrations. Silastic implants of either cyclic AMP or dibutyryl cyclic AMP decreased contractility of rat seminiferous tubules in vitro as did the incubation of seminiferous tubules with dibutyryl cyclic AMP (2 mM) and theophylline (2.8 x 10-4 M). Subcutaneous injections of melatonin (250, 500 and 1,000µ g/day) also diminished both the frequency and depth of contractions, but not tonus of siminiferous tubules. It was concluded that cyclic AMP could be a second messenger for PGE1, but not for melatonin.