Brain Research 883 (2000) 243–249 www.elsevier.com / locate / bres Interactive report Posterodorsal amygdala lesions reduce feeding stimulated by 1 8-OH-DPAT a,b, c a a d d * D.V. Coscina , P.J. Currie , C. Bishop , G.C. Parker , B.L. Rollins , B.M. King a Department of Psychology, Wayne State University, 71 W . Warren Ave., Detroit, MI 48202, USA b Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI 48201, USA c Department of Psychology, Barnard College, New York, NY 10027, USA d Department of Psychology, University of New Orleans, New Orleans, LA 70148, USA Accepted 13 September 2000 Abstract Injections of the serotonin (5-HT) agonist, 8-hydroxy-2(di-n-propylamino)tetralin, (8-OH-DPAT), either systemically or into the 1A midbrain raphe nuclei, elicit food intake in otherwise satiated rats. Lesions of the paraventricular nucleus of the hypothalamus are well known for producing long-term overeating, but past research has excluded this site as a potential locus for short-term 8-OH-DPAT feeding effects. More recent work shows that small lesions of the posterodorsal amygdala (PDA) elicit overeating in their own right. Since this and related regions of the amygdala receive 5-HT innervations from the dorsal raphe nucleus (DRN), we determined if PDA lesions might alter feeding after injecting 8-OH-DPAT into this midbrain region. Adult female rats received either bilateral electrolytic lesions of the PDA or sham lesions. After recording weight gains for over 1 month, all rats were implanted with DRN cannulae, then randomly tested every 3–4 days for 1 h intake of standard lab chow after 0, 0.4, 0.8 or 1.6 nmol injections of 8-OH-DPAT. Additional 90 min measures of intake were also made after 0 vs. 250 mg (760 nmol) 8-OH-DPAT s.c. At the two highest DRN doses tested, lesioned rats showed 50% less intake compared to shams. A similar profile emerged after the single s.c. dose. These results suggest that the PDA may be an important locus at which reduced release of endogenous 5-HT stimulates feeding. Alternatively, the PDA may represent part of a larger brain circuit whose integrity is necessary for eliciting intake in response to a variety of feeding stimuli.  2000 Elsevier Science B.V. All rights reserved. Theme: Neural basis of behavior Topic: Ingestive behavior Keywords: Serotonin; Overeating; Dorsal raphe; Intracerebral injection; Subcutaneous; Brain mapping 5-HT agonist, 8-hydroxy-2(di-n-propylamino)tetralin (8- 1. Introduction 1A OH-DPAT), or (2) blocking brain 5-HT receptors follow- ing systemic [11,13,41], intraventricular [5] or intra-cere- A variety of research has suggested that impairing bral [8] injections of 5-HT antagonists. neurotransmission in the brain’s serotonin (5-hydroxy- Attempts to determine where 8-OH-DPAT’s feeding tryptamine or 5-HT) system can lead to overeating [2]. effects are localized in the brain have implicated dopamine Two experimental techniques that have convincingly dem- and opiate systems in portions of the caudate-putamen onstrated this in rats using acute perturbations are by: (1) [14,17] and the nucleus accumbens [14,15]. Since the suppressing endogenous 5-HT release through systemic hypothalamus is well known for its involvement in control- [4,10,12,18] or intra-raphe [6,7,9,14–17] injections of the ling feeding behaviors, and enhancing 5-HT neurotrans- mission in several of its nuclei can suppress feeding [32], it 1 Published on the World Wide Web on 10 October 2000. might be expected that the increased food intake stimulated *Corresponding author. Tel.: 11-313-577-2810; fax: 11-313-577- by 8-OH-DPAT is due to a subnormal release of hypo- 7636. E-mail address: dcoscina@sun.science.wayne.edu (D.V. Coscina). thalamic 5-HT [12,24]. In particular, it might be expected 0006-8993 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0006-8993(00)02918-8