Serotonergic changes following proestrous treatment with p,p'-DDT.

The effects of 25 and 75 mg/kg p,p'-DDT on the CNS serotonergic system were examined in proestrous female rats. Females were treated with p,p'-DDT on the morning of proestrus and were sacrificed that evening. Levels of serotonin (5-HT) and its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were examined in cortex, hippocampus, hypothalamus and preoptic areas. The binding of 3'-8-OH-DPAT [2-hydroxy-2-N, N-(di-propylamino)-tetralin], an agonist for 5-HT1A receptors, was examined in hippocampus and frontal cortex. P,p'-DDT decreased the level of 5-HT in frontal cortex and hippocampus. Elevations in 5-HIAA were present in the hypothalamus but only at the higher dose of p,p'-DDT. The dose of 25 mg/kg p,p'-DDT produced an increase in the Bmax for 3H-8-OH-DPAT binding to frontal cortical and hippocampal membranes. Membrane preparations from females given 75 mg/kg p,p'-DDT fell into two categories. Some were similar to the control but with a slightly higher Kd; others could not be analyzed by traditional linear or nonlinear regression procedures because they showed a constant proportion of bound label, independent of the concentration of 3H-ligand in the reaction. In vitro, p,p'-DDT did not compete with 3H-8-OH-DPAT for binding to cortical membranes so it is unlikely that residual pesticide in the membrane preparation accounted for the binding results. These binding results are particularly interesting because, in previous studies, the dose of 25 mg/kg p,p'-DDT was shown to be more potent than 75 mg/kg p,p'-DDT in reducing female rodent lordosis behavior.(ABSTRACT TRUNCATED AT 250 WORDS)