The Effect of Clonidine Pretreatment on the Perioperative Proinflammatory Cytokines, Cortisol, and ACTH Responses in Patients Undergoing Total Abdominal Hysterectomy

Abstract

We investigated the hypothesis that oral clonidine premedication would decrease the release of proinflammatory cytokines interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, and stress hormones cortisol and adrenocorticotropic hormone (ACTH), in patients who underwent total abdominal hysterectomy. Twenty patients were randomly assigned to one of two groups: the control group received no premedication, whereas the treatment group received clonidine 0.15 mg oral dose 90 min before surgery. Venous blood samples were obtained at preinduction time and immediately, 1, and 3 h after the start of surgery. IL-6 increased significantly at 3 h, and cortisol and ACTH at 1 and 3 h after the start of surgery compared with the baseline values within both groups. IL-1β levels decreased at all times compared with the baseline value in the control group. In the comparison study between the control group and the clonidine group, there was a significant decrease in IL-6 level 3 h after the start of surgery and IL-1β at preinduction time in the clonidine group, whereas there were no changes in tumor necrosis factor-α, cortisol, and ACTH levels. These results show that clonidine modulates the IL-6 response related to surgical stress.

Implications 

We assessed the effect of the α₂-adrenoreceptor agonist clonidine on the immunoendocrine activity during the perioperative period. Clonidine 0.15 mg given as oral premedication resulted in the reduced Interleukin-6 production in response to total abdominal hysterectomy.

Clonidine can be used for premedication because it modulates hemodynamic changes during anesthetic induction, both during and after surgery, improves myocardial ischemia during surgery, and decreases major anesthetic requirements for volatile anesthetics and opioids during surgery (^1–3).

Increased proinflammatory cytokines and stress hormones have been observed after surgery (^4,5). Because the host immune competence is very important for maintaining homeostatic defense mechanisms, several attempts have been made to restore postoperative immune competence (^6,7).

There are also substantial data regarding the effects of clonidine on cortisol and adrenocorticotropic hormone (ACTH), but the results are controversial (^8–10). There have been few reports regarding clonidine’s effect on the cytokines responses. Therefore, we investigated the effect of preoperative oral clonidine on the responses of proinflammatory cytokines interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α, and the stress hormones cortisol and ACTH during the perioperative period.

Methods

After obtaining approval from the local ethics committee and individual written, informed consent, we studied 20 patients undergoing total abdominal hysterectomy. All patients were ASA physical status I or II and were randomly allocated to one of two groups (n = 10 in each) to receive no premedication or 0.15 mg (approximately 2.5 μg/kg) clonidine orally 90 min before the operation, respectively.

The usual monitors were used before the induction of anesthesia. Anesthesia was induced by thiopental sodium 5 mg/kg and pancuronium 0.1 mg/kg, followed by laryngoscopy and tracheal intubation. Anesthesia was maintained with O₂ 0.5 L/min, N₂O 0.5 L/min, and enflurane; enflurane concentration was controlled to maintain the systolic blood pressure within the range of 20% of the basal systolic pressure. Respiratory frequency and tidal volume were adjusted to maintain the end-tidal carbon dioxide level at 35 mm Hg. Esophageal temperature was maintained at 35°-37°C. For fluid therapy, all patients received balanced salt solution at a rate of 6 mL · kg⁻¹ · h⁻¹ perioperatively and 2 mL · kg⁻¹ · h⁻¹ postoperatively. Blood components were not used. At the end of surgery, neuromuscular blockade was reversed with pyridostigmine 15 mg and glycopyrrolate 0.4 mg IV. Postoperative analgesia was facilitated by using a patient controlled analgesia system (morphine 1 mg/mL, fentanyl 20 μg/mL) and was programmed to deliver 1 mL/demand with a 10-min lockout time.

Blood samples were obtained 10 min before the induction, immediately, 1 h, and 3 h after the start of surgery. Sampled blood was collected into EDTA tubes and centrifuged at 3000 rpm for 10 min at 4°C immediately after sampling. Thereafter, plasma was stored at −70°C until all the samples were collected. Cytokines, IL-6, IL-1β, and TNF-α concentrations were assayed with commercially available ELISA kits (Quantikine Supersensitive, Research & Diagnostic systems, Minneapolis, MN). The sensitivity of the assay for IL-6, IL-1β, and TNF-α was 0.7 pg/mL, 0.3 pg/mL, and 4.4 pg/mL, respectively. Cross reactivity with other factors was negligible in all cytokine assays. The plasma cortisol level was determined with radioimmunoassay by using Amerlex Cortisol RIA kit (Johnson & Johnson Clinical Diagnostics, Cardiff, UK), and ACTH measurement was conducted with immunoradiometric assay by using ELISA-ACTH kit (CIS Biointernational, Paris, France). The sensitivity of the assay for cortisol and ACTH was 3.62 ng/mL and 1.0 pg/mL, respectively. Cross reactivity with other steroids was negligible in both assays.

Parametric values were analyzed by using Student‘s t-test. Cytokines IL-6, IL-1β, and TNF-α concentrations and stress hormones cortisol and ACTH were not distributed normally, so these were expressed as median with range (25%–75%). The changes of cytokine values, cortisol, and ACTH sampled at the same time between the groups were analyzed by using Mann-Whitney ranked sum test. Differences in values of cytokines, cortisol, and ACTH at various times with respect to the baseline value within each group were analyzed by using the Kruskal-Wallis one-way analysis of variance on ranks and followed by the Dunnett’s post hoc test. P < 0.05 was considered significant.

Results

Demographic and clinical data, except average end-tidal enflurane concentration, were not different between the two groups (Table 1). IL-6 concentration increased significantly at 3 h after the start of surgery compared with the preoperative value within the groups. When IL-6 was compared between the two groups at the same time, IL-6 level was significantly lower in the clonidine group than the control group at 3 h after the start of surgery (Table 2). Compared with the preoperative value, a significant decrease of IL-1β throughout the study period was found in the control group, but no changes were found in the clonidine group. There was a significant difference in IL-1β at the preinduction period between the two groups. Statistical analysis of TNF-α values did not show any difference within or between the groups. Cortisol and ACTH levels increased rapidly at 1 h after the skin incision and continued to increase in both groups.

Table 1: Characteristics of the Patients

Table 2: Plasma Concentrations of Interleukin-6 (IL-6), Tumor Necrosis Factor-α (TNF-α), Interleukin-1β (IL-1β), Cortisol, and Adrenocorticotrophic Hormone (ACTH)

Discussion

Major surgery causes alterations in the endocrine-immune system. We found that IL-6, cortisol and ACTH increased in response to abdominal hysterectomy for both groups, whereas premedication with oral clonidine 0.15 mg significantly reduced the level of blood IL-6 at three hours after the start of surgery and IL-1β at preinduction time.

IL-6 is a main proinflammatory cytokine produced as early as two to four hours after tissue damage (^4,11) and is the primary stimulus for acute phase responses. Plasma levels of IL-6 have been reported related to the severity of the operation, the prognosis of sepsis, and the degree of postoperative complication (¹²). One mechanism of stimulation of IL-6 release is via the intracellular cAMP concentrations. IL-6 synthesis was stimulated by an increase in intracellular cAMP (^13,14). Clonidine functions by attenuating adenyl cyclase activity and then by reducing the cAMP level. However, Dorman et al. (¹⁵) demonstrated that neither oral clonidine 0.2 mg and clonidine patch nor oral 0.3 mg influenced IL-6 level in patients undergoing upper abdominal surgery. In that study, however, there was a limitation of study design in that the IL-6 value was not measured until 24 hours postoperatively. Although the blood clonidine levels were not measured in our study, we thought that IL-6 would change with the clonidine premedication, because the anesthetic technique with enflurane, and the type of surgery and its duration, which were thought to be related to the stress of the operation, were the same for the both groups.

Oral clonidine is well absorbed and used completely in the body. The pharmacological effect of clonidine appears in 1.5–2 hours, with the peak level in 3 hours. The half-life is approximately 8.5 ± 0.9 hours (¹⁶). We assessed the effect of oral premedication of 0.15 mg of clonidine on IL-6, IL-1β, TNF-α, cortisol, and ACTH until 3 hours after the beginning of surgery to avoid the influence of analgesics, such as opioids and nonsteroidal antiinflammatory drugs, during the postoperative period, and thus making the interpretation of the data clear. The suppressive effect of morphine on the immune system is well known.

The regulation of IL-1β is also dependent on intracellular cAMP signaling pathways, and drugs known to increase intracellular cAMP levels are potential inducers of IL-1β (¹⁷). However, because IL-1β appears and disappears quickly (¹⁸), we could only demonstrate its differences between the two groups at preinduction time, which was approximately 75–80 minutes after administering the oral clonidine. Thereafter, we were not able to demonstrate the response of clonidine on IL-1β concentrations.

Activation of the hypothalamo-pituitary-adrenal axis and the cortisol secretion associated with surgical trauma are very important perioperative stress responses. In this study, cortisol and ACTH increased significantly during the study period compared with the preinduction level in both groups, but no inhibition of these changes was found with clonidine premedication. Previous studies reported controversial effects of clonidine premedication on blood cortisol level associated with surgery (^9,19). The precise mechanism of the effect of clonidine on ACTH is not known, and its effects on ACTH levels in healthy humans is variable (^10,20). Endocrine stress response may also be modified by the administration of opioids; therefore we assessed the effect of clonidine to three hours after the start of surgery.

This study may be criticized for the small size of the two groups and the low power of the performed test (below the desired power of 0.8) in the negative results. However, the decreased response of IL-6 by clonidine may contribute to attenuation of postoperative complications related to high IL-6 responses.

We conclude that IL-6 response to pelvic surgery was attenuated at three hours after the start of surgery by oral clonidine.

The authors wish to thank Sangeun Lee for her technical assistance.