Neurophysiology of Opiate Dependence

Abstract

The physiological activity of neurons requires energy derived from the metabolism of glucose. The mapping and quantification of regional glucose utilization rates by the 2-deoxy-D-[1-14C] glucose is a method that provides an index of regional functional activity in the central nervous system.1 This method has been used to investigate the functional cerebral anatomy of both spontaneous and naloxone-precipitated morphine withdrawal. A selective and highly reproducible enhancement on rates of glucose utilization was found during morphine withdrawal.2–4 The regional distribution of this elevated metabolic activity was similar during spontaneous and naloxone-precipitated withdrawal, but a smaller magnitude of changes overall was observed in spontaneous withdrawal that could reflect its reduced behavioral intensity compared to precipitated withdrawal.3 The hypermetabolism was primarily produced in thalamic and limbic areas, particularly the central nucleus of amygdala. Several hypothalamic nuclei, including the posterior nucleus, the paraventricular nucleus and the lateral area, showed increased metabolic activity. Other midbrain regions, such as locus coeruleus, ventral tegmental area, dorsal parabrachial nucleus, superior colliculus, dorsal tegmental nucleus and median raphe, also increased their glucose utilization rates.