Electron microscopic evidence that bretylium and pargyline delay adrenergic nerve degeneration after sympathectomy of the pineal gland.

Seventeen and twenty four hours after sympathetic denervation, noradrenaline stores of the rat pineal gland were depleted to 50% and 10% of controls, respectively. Electron microscopic studies showed the coexistence of normal and altered nerve endings 17 h after denervation, while 24 h after denervation, only degenerated nerve terminals were observed. Treatment with pargyline (512 mumoles/kg) or bretylium (24 mumoles/kg) significantly delayed the loss of noradrenaline from denervated glands. In pargyline treated rats, 17 h after denervation, noradrenaline stores were 90% of control glands. After bretylium, values obtained 24 h after denervation, declined to 36% of innervated glands. Persistence of neurotransmitter coincided with the presence of normal nerve endings as observed electron microscopically. It is concluded that both, pargyline and bretylium, prolonged the survival of nerve endings severed from the cell body.