Importance of μ,δ and κ Opioid Receptors in Cardiovascular Depression Following Traumatic Hemorrhagic Shock in Rats

Aim To investigate the importance of μ, δ and κ opioid receptors in the cardiovascular depression following traumatic hemorrhagic shock, elucidate the facts that the subclass of these opioid receptors is involved in the pathogenesis of traumatic hemorrhagic shock. Methods With a model of traumatic hemorrhagic shock rat, the relationship between the changes of myocardial and brain μ, δ and κ opioid receptors and cardiovascular functions and effects of δ and κ opioid receptor antagonists on hemodynamic parameters of traumatic hemorrhagic shock rats were observed. Results The number of myocardial and brain δ and κ opioid receptors significantly increased, and they were significantly associated with the decreased hemodynamic parameters such as mean arterial pressure (MAP), left intraventricular systolic pressure (LVSP), the maximal rate of the change of intraventricular pressure (±dp/dtmax) and the area of pdp/dt vector loop (Lo). However, μ opioid receptor of heart and brain did not obviously alter and δ opioid receptor antagonist ICI78, 864 and κ opioid receptor antagonist Norbinaltorphimine (50μg, icv) could significantly reverse those decreased hemodynamic parameters of traumatic hemorrhagic shock rats. Conclusion These results suggest that opioid receptors, especially δ and κ opioid receptors, are closely related to the pathogenesis of traumatic hemorrhagic shock, and they play an important role in the depression of cardiovascular function following traumatic hemorrhagic shock.