Effects of long-term administration of chlorpromazine on the pineal gland of rats.

Long-term (6 months) administration of 25 mg/kg body weight/day chlorpromazine (CPZ) to rats resulted in remarkable inhibition of normal increase with age of osmiophilic lipid droplets (OLD) in the pineal gland, and atrophy of pinealocytes. The breeding conditions such as illumination, humidity, and room temperature were strictly controlled. Hence, these changes were ascribed solely to the effects of the drug. OLD are considered as an indicator of physiological activity of the gland. In view of the possible functional relations of this organ to endocrine or autonomic nervous activity, our finding may give a clue to the clarification of the possible cause of some side-effects of the drug.