Behavior and brain growth in rats treated with p-chlorophenylalanine in the first weeks of life.

Abstract

AbstractIntraperitoneal injections of p‐chlorophenylalanine (pCPA) were given to 71 rats in the first 7 weeks of life, decreasing brain 5‐hydroxytryptamine concentrations to 20% of control values. The brain weight was significantly decreased, evident after 2 weeks of treatment, and also 52 days after the last injection. The retarded brain growth was not due to a general growth inhibition only: body weight was decreased initially, but from Day 24 the experimental animals gained weight more rapidly than the controls, resulting in a significantly higher body weight from Day 67.The decrease in brain growth was accompanied by behavioral changes, evident later in life. The first test was given 4 weeks after the last pCPA‐injection. The changes observed were moderate, but consistent in all the tests. There were no learning deficits or clear motivational changes. In all the tests there was evidence of a reduced arousal level in the pCPA‐treated rats: latencies were long, exploration was low, habituation to new environment was fast, and the reactivity was low.