24-Hour Pretreatment with δ Opioid Enhances Survival from Hemorrhagic Shock

Acute therapeutic use of 5-aminoimidazole-4-carboxamide ribonucleoside extends survival interval in response to severe hemorrhagic shock

This study tests the hypothesis that pretreatment and/or posttreatment with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an inducer of adenosine monophosphate-activated protein, will extend the golden hour of survival time in rats subjected to severe hemorrhagic shock in the absence of available fluid resuscitation. Three days before hemorrhage, at 24-h intervals, animals were given three i.p. injections of AICAR (pretreatment) or saline (control/posttreatment). At the end of hemorrhage, animals (control/pretreatment) received a single i.v. injection of saline, whereas the posttreatment group received a single i.v. injection of AICAR (posttreatment). All treatment groups received the same total volume of fluid both before and immediately after hemorrhage. Both AICAR treatment groups had significantly(P < 0.01) extended survival time during the decompensatory phase of shock when compared with saline control group, pretreatment: 324 ± 21 min; posttreatment: 187 ± 16 min; and saline: 55 ± 10 min. Heart rate was significantly (P < 0.01) decreased following hemorrhage for pretreatment animals versus saline controls, 237 ± 16 vs. 312 ± 33 beats/min, respectively. Heart rate for both the pretreatment and posttreatment animals was also significantly (P < 0.01) lower after 30 min versus saline control group, pretreatment: 247 ± 13 beats/min; posttreatment: 240 ± 20 beats/min; saline: 415 ± 18 beats/min. Lactate levels were also significantly reduced 6.3 ± 0.71 mmol/L (pretreatment), 7.1 ± 0.47 mmol/L (posttreatment), 8.9 ± 0.21 mmol/L (saline). The improvement in hemodynamic stability is reflected in the significant increase in the golden-hour survival time in animals subjected to severe hemorrhagic shock.

Mimetics of hormetic agents: stress-resistance triggers

Mimetics of hormetic agents offer a novel approach to adjust dose to minimize the risk of toxic response, and maximize the benefit of induction of at least partial physiological conditioning. Nature selected and preserved those organisms and triggers that promote tolerance to stress. The induced tolerance can serve to resist that challenge and can repair previous age, disease, and trauma damage as well to provide a more youthful response to other stresses. The associated physiological conditioning may include youthful restoration of DNA repair, resistance to oxidizing pollutants, protein structure and function repair, improved immunity, tissue remodeling, adjustments in central and peripheral nervous systems, and altered metabolism. By elucidating common pathways activated by hormetic agent's mimetics, new strategies for intervention in aging, disease, and trauma emerge. Intervention potential in cancer, diabetes, age-related diseases, infectious diseases, cardiovascular diseases, and Alzheimer's disease are possible. Some hormetic mimetics exist in pathways in primitive organisms and are active or latent in humans. Peptides, oligonucleotides, and hormones are among the mimetics that activate latent resistance to radiation, physical endurance, strength, and immunity to physiological condition tolerance to stress. Co-activators may be required for expression of the desired physiological conditioning health and rejuvenation benefits.

Post-treatment with the novel deltorphin E, a delta2-opioid receptor agonist, increases recovery and survival after severe hemorrhagic shock in behaving rats

Deltorphin E was investigated as a pharmaceutical intervention in the ischemic hemorrhagic model. To monitor the hemodynamic biomarkers mean arterial pressure (MAP) and heart rate (HR) and to facilitate i.v. injections, rats were surgically fitted with femoral artery and vein catheters under anesthesia. After removal of 48% of total blood volume (range, 12-15 mL), posthemorrhage i.v. injections of 5.5-mg/kg deltorphin E were found to significantly (P < 0.05) increase maximum MAP, pulse pressure, and survival after hemorrhage, whereas lactic acid concentration was decreased when compared with saline injections. The results for the 5.5-mg/kg deltorphin E-treated animals versus saline controls showed the following values (expressed as mean +/- SEM): maximum MAP, 58 +/- 7 vs. 35 +/- 9 mmHg, respectively; lactic acid, 6.5 +/- 1.25 vs. 8.9 +/- 0.12 mmol/L, respectively; pulse pressure, 47.9 +/- 0.55 vs. 38.3 +/- 0.44 mmHg, respectively; and at least a fourfold increase in survival, 331 +/- 18 vs. 50 +/- 8 min, respectively. Heart rate in deltorphin E-treated groups was not significantly different from that in saline-treated groups (maximum HR, 396 +/- 40 vs. 425 +/- 94 bpm, respectively). Using logistic analysis, deltorphin E did not significantly alter the baroreflex sensitivity. However, a significant deltorphin E dose-dependent correlation was found between survival time and lactic acid production. Increased pulse pressure was also correlated with survival. Glibenclamide, a potassium-sensitive adenosine triphosphate-sensitive channel blocker, did not interfere with the positive effects of deltorphin E. Only the antagonists tested, known to affect delta(2)-opioid receptors, interfered with the deltorphin E survival benefit after hemorrhage. As a conclusion, deltorphin E is an effective pharmaceutical intervention in severe hemorrhagic shock and, perhaps, in other ischemic shock scenarios when administered after the onset of stress. Therefore, deltorphin E may have clinical potential.