Ultrastructural mechanisms of serotonin demyelination

Abstract

The effect of serotonin on the ultrastructure of the white matter in the CNS of dogs was studied. Intracisternal injection of the amine (6 μg in 0.1 ml physiological saline) led to considerable disturbances in the myelin and glia in regions of the white matter of the spinal cord adjacent to the cerebrospinal fluid channels. Loss of the regular structure and separation of the lamellae of the myelin with rupture and lysis of the myelin sheath and demyelination were observed. Vacuolar degeneration was observed in the oligodendrocytes; the astrocytes were virtually unchanged. After local intracerebral injection of the amine (2 μg in 0.01 ml physiological saline) similar disturbances developed in the white matter of the cerebral hemispheres, but with features of an inflammatory reaction in the late stages of the investigation. In control animals which received injections of physiological saline, changes appeared later and only in the gliocytes. It is concluded that serotonin has the property of injuring myelin and glia.