Opioid receptors associated with cardiovascular depression following traumatic hemorrhagic shock in rats.
OBJECTIVE: To elucidate which one of &mgr;, delta and kappa opioid receptors is involved in the cardiovascular depression following traumatic hemorrhagic shock. METHODS: With traumatic hemorrhagic shock rat models, the changes of myocardial and brain &mgr;, delta and kappa opioid receptors and cardiovascular functions and their relationship with hemodynamic parameters were observed. The effects of delta and kappa opioid receptor antagonists on hemodynamic parameters of traumatic hemorrhagic shock rats were observed. RESULTS: Following traumatic hemorrhagic shock, the number of myocardial and brain delta and kappa opioid receptors significantly increased, their affinity did not alter, and the increased number of delta and kappa opioid receptors was significantly associated with the decreased hemodynamic parameters. However, &mgr; opioid receptor in heart and brain did not obviously change. delta opioid receptor antagonist ICI174,864 and kappa opioid receptor antagonist Nor-binaltorphimine (50 &mgr;g, Icv) could significantly reverse those decreased hemodynamic parameters. CONCLUSIONS: It suggests that opioid receptors, especially delta and kappa opioid receptors are closely related to the pathogenesis of traumatic hemorrhagic shock, and they play important roles in the depression of cardiovascular function following traumatic hemorrhagic shock.