Rats self-inject a dopamine antagonist in the lateral hypothalamus where it acts to increase extracellular dopamine in the nucleus accumbens

Abstract

Local injection of sulphide to block dopamine (primarily D 2type) receptors in the perifornical lateral hypothalamus (pf-LH) can induce locomotion, feeding, and drinking, and in the present study, local sulphide induced reward and dopamine (DA) release in the nucleus accumbens. Sulpiride injected bilaterally (4, 8, and 16 μg/0.3 μl), ipsilaterally, or contralaterally (8 μg) in the pf-LH increased extracellular levels of DA and its metabolites in the accumbens. Bilateral sulpiride injected posterior and medial to the pf-LH controlled for diffusion to the ventricle or ventral midbrain. Rats self-injected sulpiride (210 ng/21 nl/2 s) in the pf-LH (111 resp/2 h on drug lever vs. 20 resp on a blank lever). Thus, cells in the pf-LH establish connections with mesolimbic DA neurons involved in the behavior reinforcement process. Evidently hypothalamic cells with DA receptors normally inhibit aspects of behavior reinforcement. Disinhibition with hypothalamic sulpiride is reward for self-injection and cause of overeating that can lead to obesity.