DOPAMINE AGONISTS AND STRESS PRODUCE DIFFERENT PATTERNS OF FOS-LIKE IMMUNOREACTIVITY IN THE LATERAL HABENULA

In rats treated systemically with either amphetamine, amfonelic acid o r apomorphine, large numbers of cells displaying Fos-like immunoreacti vity (FLI) could be seen in the lateral zone of the lateral habenula. The induction of FLI by amphetamine could be blocked either by pretrea tment with haloperidol or by 6-hydroxydopamine lesions of ascending do pamine fibers at the level of the lateral hypothalamus. In contrast, a variety of stressors selectively induced FLI in the most medial porti on of the lateral habenula. These findings support the concept of a fu nctional differentiation of the medial and lateral regions of the late ral habenula and provide further evidence for involvement of the haben ula in the circuitry of the basal ganglia.