1. ¹Department of Anatomy and Morphological Neuroscience, Shimane University School of Medicine, Izumo, Japan
2. ²Department of Neurology, Beth Israel Deaconess Medical Center, Boston, and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
3. ³Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA

Correspondence: Dr T Kishi, MD, PhD, Department of Anatomy and Morphological Neuroscience, Shimane University School of Medicine, Izumo 693-8501, Japan. E-mail: tkishi@med.shimane-u.ac.jp

Received 28 September 2004; Revised 30 November 2004; Accepted 30 November 2004; Published online 4 January 2005.

Abstract

Regulated energy homeostasis is fundamental for maintaining life. Unfortunately, this critical process is affected in a high number of mentally ill patients. Eating disorders such as anorexia nervosa are prevalent in modern societies. Impaired appetite and weight loss are common in patients with depression. In addition, the use of neuroleptics frequently produces obesity and diabetes mellitus. However, the neural mechanisms underlying the pathophysiology of these behavioral and metabolic conditions are largely unknown. In this review, we first concentrate on the established brain machinery of food intake and body weight, especially on the melanocortin and neuropeptide Y (NPY) systems as illustration. These systems play a critical role in receiving and processing critical peripheral metabolic cues such as leptin and ghrelin. It is also notable that both systems modulate emotion and motivated behavior as well. Secondly, we discuss the significance and potential promise of multidisciplinary molecular and neuroanatomic techniques that will likely increase the understanding of brain circuitries coordinating energy homeostasis and emotion. Finally, we introduce several lines of evidence suggesting a link between the melanocortin/NPY systems and several neurotransmitter systems on which many of the psychotropic agents exert their influence.