μ-Opioid receptors and limbic responses to aversive emotional stimuli

^†Psychiatry and ^¶Nuclear Medicine Services, Veterans Administration Medical Center, Ann Arbor, MI 48105; and Departments of ^*Psychiatry and Radiology, ^§Division of Nuclear Medicine, University of Michigan, Ann Arbor, MI 48109

Communicated by Edward E. Smith, University of Michigan, Ann Arbor, MI (received for review June 22, 2001)

Abstract

Functional neuroimaging studies implicate limbic and paralimbic activity in emotional responses, but few studies have sought to understand neurochemical mechanisms which modulate these responses. We have used positron emission tomography to measure μ-opioid receptor binding, and cerebral blood flow in the same subjects, and demonstrated that the baseline binding potential and the regional cerebral blood flow in the left inferior temporal pole are functionally related. Higher baseline μ-opioid receptor binding potential was associated with lower regional cerebral blood flow in this region during presentation of emotionally salient stimuli. This is consistent with an inhibitory/anxiolytic role of the endogenous opioid system in limbic regions of the temporal lobe and basal forebrain.

Footnotes

↵ ‡ To whom reprint requests should be addressed. E-mail: liberzon{at}umich.edu.
↵ ‖ Phan, K., Liberzon, I. & Taylor, S. (2000) Soc. Neurosci. Abstr. 2, 755.17.
Abbreviations:

PET,

positron emission tomography;

BP,

binding potential;

rCBF,

regional cerebral blood flow;

SLEA,

sublenticular extended amygdala;

VOI,

volumes of interest;

CFN,

carfentanil;

PTSD,

posttraumatic stress disorder;

mPFC,

medial prefrontal cortex;

DV,

distribution volume;

PANAS,

positive affectivity–negative affectivity scale