The effect of cysteamine on immunoreactive somatostatin in the rabbit retina.

Cysteamine hydrochloride was administered to rabbits at doses ranging from 0.3 to 10 mg by two intravitreal injections 24 h apart. Retinal immunoreactive somatostatin concentrations were reduced by about 50% at 24 h following the second injection. At doses of 0.3-3 mg, there was no demonstrable effect on retinal concentrations of immunoreactive substance P or of dopamine. Ten milligrams of cysteamine produced non-specific retinal damage. Cysteamine injected locally into the retina is a relatively specific drug for depletion of somatostatin.