Effect of prenatal dopamine receptor blocking on somatostatin receptor binding in the developing rat brain

To date, the possible functional interaction between the dopaminergic and the somatostatinergic system during the development of the brain is unknown. This study examines whether blockage of brain dopamine receptors during fetal life might influence postnatal somatostatin (SS) receptor development. Pregnant Sprague-Dawley rats were injected intraperitoneally with either haloperidol (2.5 mg/kg/day), which blocks dopaminergic receptors, or saline. The injections were given for 16 days, commencing on the 4th or 5th day after conception (as counted from the appearance of spermatozoa in daily vaginal smear). The administration of haloperidol during gestation did not affect the levels of somatostatin-like immunoreactivity (SLI) in the two brain areas at any of the times studied. However, this treatment resulted in a decrease in the total number of receptors for 125I-Tyr11-SS in frontoparietal cortex and hippocampal plasma membranes in the 14-day-old offspring but not at 21, 35, or 60 days after birth. No significant differences in the apparent SS binding affinity values were seen after fetal exposure to haloperidol. These results suggest that the development of SS receptors in rat frontoparietal cortex and hippocampus can be transitorily delayed by fetal blockage of dopamine receptors.