REASSESSMENT OF THE SIGNIFICANCE OF DARK NEURONS IN SEROTONERGIC CELL GROUPS

Mature, Sprague-Dawley and Holtzman rats were injected intraperitoneally with varying doses of fenfluramine (1.0-31.6mg/kg), reserpine (5mg/kg), methamphetamine (10mg/kg) and p-chloroamphetamine (10 mg/kg). Midbrain sections were studied using two different histologie techniques. Hyperchromatic and argyrophilic (dark) neurons were seen in all treated animals as well as in salinetreated controls. These changes were seen less frequently in frozen sections and were not associated with neuronal loss or with glial reaction except in a few rats treated with p-chloroamphetamine. This supports the current concept that dark neurons are artifacts and are not indicative of pathologic change. © 1979.