Apomorphine-induced facilitation of intracranial self-stimulation following dopamine denervation of the nucleus accumbens.
Two groups of rats were trained to lever press for intracranial self-stimulation (ICSS) from electrodes aimed at the posterior lateral hypothalamus or at the region of the locus coeruleus. Following stabilization of baseline responding using descending rate/intensity functions, bilateral 6-hydroxydopamine (6-OHDA) lesions to the nucleus accumbens (N.Acc.) were performed. Subsequent injections of apomorphine (SC) resulted in significant increases in self-stimulation in both lesion groups and significant decreases in self-stimulation in both groups of sham operated animals. These results indicate that the destruction of the dopaminergic terminals in the nucleus accumbens results in a "supersensitive" enhancement of the ICSS stimulating properties of apomorphine regardless of the electrode placement. Both lesion groups also showed a pronounced increase in locomotor activity in photocell cages following treatment with the same dose of apomorphine. These results complement previous work showing that dopamine destruction affects ICSS regardless of electrode placement and support the hypothesis that the midbrain dopamine systems have a general response enabling role in reinforced behavior.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D004298:Dopamine / Q000502:physiology*; D004558:Electric Stimulation; D006892:Hydroxydopamines / Q000494:pharmacology; D007026:Hypothalamic Area, Lateral / Q000187:drug effects; D008125:Locus Coeruleus / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects; D009638:Norepinephrine / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects; D012653:Self Stimulation / Q000187:drug effects* / Q000502:physiology; D012686:Septal Nuclei / Q000502:physiology*
D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D016627:Oxidopamine; D001058:Apomorphine; D004298:Dopamine; D009638:Norepinephrine