Opioid receptors associated with cardiovascular depression following traumatic hemorrhagic shock in rats.

Objective: To elucidate which one of μ, δ and κ 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 μ, δ and κ opioid receptors and cardiovascular functions and their relationship with hemodynamic parameters were observed. The effects of δ and κ opioid receptor antagonists on hemodynamic parameters of traumatic hemorrhagic shock rats were observed. Results: Following traumatic hemorrhagic shock, the number of myocardial and brain δ and κ opioid receptors significantly increased, their affinity did not alter, and the increased number of δ and κ opioid receptors was significantly associated with the decreased hemodynamic parameters. However, μ opioid receptor in heart and brain did not obviously change. δ opioid receptor antagonist ICI174,864 and κ opioid receptor antagonist Nor binaltorphimine (50 μg, Icv) could significantly reverse those decreased hemodynamic parameters. Conclusions: It suggests that opioid receptors, especially δ and κ 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.