Effect of neurotensin, substance P and TRH on the regulation of dopamine receptors in rat brain.

Rats were exposed for one week to either neurotensin (4 micrograms/h), substance P (3.3 micrograms/h), thyrotropin-releasing hormone (5 micrograms/h), or saline administered intracerebroventricularly via mini osmotic-pumps and either haloperidol (2.5 mg/kg i.p., 2 X daily) or vehicle control. The peptide treatments by themselves did not alter [3H]spiroperidol binding in either the nucleus accumbens or the striatum. Neurotensin, however, augmented the increase in [3H]spiroperidol binding caused by the haloperidol treatment in both the nucleus accumbens and striatum.