Hemorrhage is associated with an impairment in the immune response and with increased concentrations of circulating inflammatory cytokines. The present study determined the time course and localization of alterations in circulating and tissue pro-inflammatory cytokines (TNF-α, IL-1-α and -β) in response to fixed-pressure (40 mm Hg) hemorrhage as well as the associated hanges in circulating neurohormonal and opioid mediators. Conscious unrestrained non-heparinized male Sprague-Dawley rats (n = 24) underwent hemorrhage followed by standard resuscitation with lactated Ringer’s solution. Animals were sacrificed at three time points; immediately after the hemorrhage period, at completion of resuscitation and 1.5 h after the resuscitation period. Hemorrhage resulted in marked elevations in circulating levels of TNF-α, which averaged 860 ± 201 pg/ml. The levels were similarly elevated following fluid resuscitation (877 ±196 pg/ml) and had decreased towards baseline 1.5 h after completion of resuscitation (281 ±134 pg/ml). TNF-α was not detectable in plasma of time-matched controls. Hemorrhage elevated TNF-α content in spleen (25%), lung (55%) and heart (20%), and tissue content remained elevated despite resuscitation. No significant changes in tissue content of TNF-α were detected in the liver, kidney or brain. Circulating levels of IL1-α and -β were not detectable in either the time-matched controls or hemorrhaged animals. However, statistically significant elevations in tissue content of IL-1α were observed in heart, spleen, lung, gut and whole brain (15–30%). Tissue content of IL-1β did not change in response to hemorrhage and/or fluid resuscitation. Activation of sympathetic outflow, as evidenced by a 3- to 4-fold elevation in circulating epinephrine and norepinephrine levels, was observed immediately after hemorrhage, and was associated with a 5-fold rise in circulating β-endorphin. These results demonstrate an early increase in tissue cytokine content following hemorrhagic shock, which is associated with elevations in circulating catecholamines and endogenous opioids, consistent with their potential modulatory role in this response.
All Science Journal Classification (ASJC) codes
- Endocrine and Autonomic Systems