Effects of hypothalamic self-stimulation of drugs influencing dopaminergic neurotransmission injected into nucleus accumbens and corpus striatum of rats

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Abstract
The role of the nucleus accumbens septi (ACB) and corpus striatum (CPU) in self-stimulation were investigated by injecting directly or indirectly acting stimulant drugs or a dopamine-(DA-) receptor blocking agent into each site bilaterally. d-Amphetamine (68 nmol) facilitated hypothalamic self-stimulation when injected into either site. Apomorphine (40 nmol) depressed or facilitated responding, the direction and magnitude of this effect being contingent (C=0.52) on the effect of systemic injection (0.3 mg/kg i.p.), and correlated with the difference between the effects of d-and l-amphetamine (0.5 mg/kg i.p.) but not with injection site. Haloperidol (6.6 nmol) in either site depressed self-stimulation. Tyramine (730 nmol), an agent believed to cause noncontingent displacement of transmitter from catecholamine terminals, depressed self-stimulation when injected into CPU, but facilitated it when injected into ACB. The sitespecific effects found with tyramine but not with apomorphine may have been due to release by tyramine of transmitters other than DA.