Posted by djmmm on May 20, 2002, at 13:54:35
Low Mu-Opioid Receptor Binding Linked to Response to Emotional Stimulus
NEW YORK (Reuters Health) May 14 - New research suggests that low levels of mu-opioid receptor binding in the limbic system are associated with a stronger than normal response to emotional stimulation.
According to investigators from the University of Michigan at Ann Arbor, this finding may explain the mechanism underlying such psychiatric conditions as posttraumatic stress disorder (PTSD) and depression, and could lead to new pharmacologic approaches to treat these disorders.Dr. Israel Liberzon and colleagues describe in the May 14th issue of the Proceedings of the National Academy of Sciences a "marriage" of two techniques, both using positron emission tomography. To estimate regional cerebral blood flow, they assessed emission scans after intravenous injection of radioactive water. For mu-opioid receptor binding, they injected the radioactive ligand carfentanil and measured its uptake.
Dr. Liberzon's group first measured regional blood flow in 12 healthy male volunteers. They then measured mu-opioid receptor binding as the men were shown images from the standardized international affective picture system. These included aversive images, such as facial mutation, wounds, and dead bodies, while neutral images included faces with neutral expressions and benign scenes. Blank images consisted of a fixation mark on a field of gray.
There was a significant negative correlation between mu-opioid receptor availability in the inferior temporal pole at baseline and cerebral blood flow during the aversive and the nonaversive stimuli.
"This methodology delineates potential neurochemical mechanisms involved in the regulation of mood and activation of regions in the brain," Dr. Liberzon told Reuters Health. "Studying these mechanisms will be important in understanding how dysregulation of emotional responses can occur in psychiatric disorders."
He noted that "we find abnormal activity in PTSD in the same brain region in which we find this relationship between the mu-opioid system and activation in response to emotional stimuli." He speculated that PTSD might also involve abnormalities in the mu-opioid system.
poster:djmmm
thread:107075
URL: http://www.dr-bob.org/babble/20020517/msgs/107075.html