Effects of traumatic brain injury in rats on binding to forebrain opiate receptor subtypes.
Sprague-Dawley rats were subjected to a moderate level (2.2 atm) of traumatic brain injury (TBI) using fluid percussion. Injured animals were allowed to survive posttrauma for periods of 5 min, 3 h, and 24 h. The effect of TBI on binding to forebrain opiate receptors was assessed using quantitative receptor autoradiography, and compared to a sham control group. Binding of [3H]DAGO to mu receptors in neocortex and the CA1 pyramidal layer of the hippocampus was significantly decreased in the 24-h group (p less than 0.05). [3H]Bremazocine binding to kappa receptors was unchanged at 5 min and 24 h, but showed large decreases 3 h after TBI in the CA1 pyramidal layer (65%, p less than 0.05) and dentate gyrus (43%, p less than 0.05). Levels of delta binding (measured with [3H]DSLET) and lambda binding (measured with [3H]naloxone) were unaffected by TBI. These data support previous suggestions of a role for endogenous opioids in TBI, and provide further evidence that mu and kappa opioid receptor subtypes in neocortex and hippocampus may have different functions in TBI.
Perry
D C
DC
Department of Pharmacology, George Washington University Medical Center, Washington, D.C. 20037.
Lyeth
B G
BG
Miller
L P
LP
Getz
R L
RL
Jenkins
L W
LW
Hayes
R L
RL
D000595:Amino Acid Sequence; D000818:Animals; D001575:Benzomorphans / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D001930:Brain Injuries / Q000378:metabolism*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism; D008969:Molecular Sequence Data; D009270:Naloxone / Q000378:metabolism; D016548:Prosencephalon / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu
D001575:Benzomorphans; D004745:Enkephalins; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; D004743:Enkephalin, Leucine; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; C027248:bremazocine