Prolonged disruption of plasma beta-endorphin dynamics following surgery

Effects of Morphine and Time of Day on Pain and Beta-Endorphin

Clients report more pain at some times of day than at others due, in part, to the temporal variation of the body's inhibitory pain response. The analgesic effectiveness of morphine varies with the time of day, perhaps due to the inhibiting or enhancing effects of the drug on plasma beta-endorphin (BE). This experiment was designed to examine the timed effects of morphine on the pain-induced BE response. Six groups of treatment mice (injected with morphine sulfate) and 6 groups of control mice (injected with saline) were exposed to an acute pain stimulus at 4-h intervals, and blood was collected. Plasma BE was analyzed using radioimmunoassay. Control mice showed a robust cir-cadian BE-response rhythm with a peak at 0000 and a nadir at 1200, whereas the BE response of mice that received morphine was arrhythmic. Animals that received morphine tolerated the noxious stimulus longer, but the analgesia varied with time of day. These results indicate that morphine abolishes the rhythmic BE response to pain and does not inhibit pain equally at all times of day. Morphine doses should be titrated to maximize the endogenous pain control system while achieving analgesia with decreased dosages.

Effects of bupivacaine infiltration on beta-endorphin and cortisol release and postoperative pain following inguinal herniorrhaphy in children

This study was undertaken to investigate the effects of bupivacaine on beta-endorphin (BE) and cortisol (C) release and postoperative pain in children. Thirty children aged 1 month to 2 years undergoing outpatient inguinal hernia under general anesthesia were randomized into three groups. Wound infiltration in group 1 patients (precisional group) was performed with 0.5 ml/ kg 0.25% bupivacaine following anesthesia induction but prior to surgery. Group 2 patients (postincisional group) had wound infiltration with bupivacaine following repair of the hernia but before skin closure. Group 3 patients (control group) did not receive any local anesthetic. In the post-anesthesia care unit (PACU) objective pain assessments were performed every 5 min using a standardized ten-point objective pain scale. Plasma C concentrations increased at the end of the operation in all groups, but this increase was significant only in the control group (P < 0.001). There was no significant difference between the pre- and postincisional groups with regard to pre- and postoperative C alterations (P > 0.05). Although plasma BE concentrations increased significantly at the end of the operation in the control group (P < 0.001), no significant difference was found between pre- and postoperative values in the infiltration groups. There was a more marked difference in BE release between the preincisional and control groups (P < 0.001) than the postincisional group (P < 0.05). Although the objective pain scores were not statistically different upon PACU arrival, the patients in the infiltration groups achieved a pain score of 0 much more quickly than those in the control group (P < 0.05). These findings suggest that wound infiltration with bupivacaine decreases the stress response to surgery and postoperative pain.

The neuropathogenesis of delirium. A need to focus our research

Delirium symptoms suggest dysfunction of multiple brain regions. However, little is known about delirium's underlying neuropathogenesis. This article addresses the need for research on neuroanatomic and neuropathophysiologic underpinnings of delirium, analogous to that of schizophrenia and affective disorders. Electrophysiologic tests, structural and functional brain imaging, and neurotransmitter studies in delirium are critically reviewed. The importance of both cerebral cortical and subcortical areas is noted, with emphasis on frontal, right-hemisphere, and subcortical regions, including caudate and anteromedial thalamus. Each symptom of delirium can be viewed from a neuroanatomic and neurochemical perspective. Recommendations for research are made throughout the article.

Hormonal and metabolic response to operative stress in the neonate

It is evident from this review that newborns, even those born prematurely, are capable of mounting an endocrine and metabolic response to operative stress. Unfortunately, many of the areas for which a relatively well-characterized response exists in adults are poorly documented in neonates. As is the case in adults, the response seems to be primarily catabolic in nature because the combined hormonal changes include an increased release of catabolic hormones such as catecholamines, glucagon, and corticosteroids coupled with a suppression of and peripheral resistance to the effects of the primary anabolic hormone, insulin.

The patterns of stress response in patients undergoing thyroid surgery under acupuncture anaesthesia in China

The patterns of catecholamines (adrenaline and noradrenaline), peptide hormones (adrenocorticotropic hormone, antidiuretic hormone, beta-endorphin, growth hormone and prolactin), hydrocortisone (cortisol) and those of immunoglobulins (IgA, IgG and IgM) and total and differential leucocyte counts in the peripheral blood were investigated during and for 6 days after thyroid surgery in 20 patients (F/M: 18/2) performed under acupuncture anaesthesia, supplemented by small doses of pethidine (mean: 45.0 mg, s.d. 8.9). Throughout surgery the patients remained conscious. During surgery a significant increase in the level of catecholamines and the above-mentioned circulating hormones and a decrease of immunoglobulins were observed, whereas the leucocyte and differential counts demonstrated leucocytosis due to lymphocytosis, a decreased percentage of eosinophils and a remarkably reduced percentage of neutrophils. In the postoperative phase, levels of noradrenaline and beta-endorphin remained elevated, whereas the other circulating hormones gradually returned to normal values. Immunoglobulin levels and eosinophil counts returned to the preinduction values within 24 h, and those of neutrophil and lymphocyte counts within 2 days. Changes in number of monocytes and basophils could not be detected peri- and postoperatively.

Opioid peptides from milk as a possible cause of sudden infant death syndrome

Milk from breast or baby formula is the exclusive source of nutrition for newborn infants. Short chain opioid peptides such as beta-casomorphins have been isolated from breast milk as well as baby formula. These biologically active peptides are absorbed from the gastrointestinal tract. In infants predisposed to respiratory apnea because of abnormal autonomic nervous system development and respiratory control mechanisms, opioid peptides derived from milk might be one of the etiological factors for sudden infant death syndrome and near miss sudden infant death syndrome.

Vasoactive neurochemicals identified in omentum: a preliminary report

There has been increasing interest in biologic, immunologic, and chemical activity originating from omental tissue. Since clinical improvement has been observed in some patients very shortly after surgically transposing their omentum to the spinal cord or brain, the question arose as to whether neurochemicals might be present in omental tissue; a possible explanation for some of these neurological changes. This paper reports the presence of vasoactive neurochemicals in canine omental tissue. It remains unclear, however, whether the omentum produces or simply concentrates these and other neurochemicals.

Endogenous opiates: 1985

This paper is the eighth installment of our annual review of research involving the endogenous opiate peptides. It is restricted to the non-analgesic and behavioral studies of the opiate peptides published in 1985. The specific topics this year include stress, tolerance and dependence, eating, drinking and alcohol consumption, gastrointestinal and renal activity, mental illness, learning and memory, cardiovascular responses, respiration and thermoregulation, seizures and neurological disorders, activity, and some other selected topics.

Endorphins in primate hemorrhagic shock: beneficial action of opiate antagonists

The endogenous opiate beta-endorphin is released concomitantly with adrenocorticotropin from the pituitary during stress. In the present study we investigated the possible involvement of opiate receptors in the cardiovascular depression associated with hypovolemic shock in the nonhuman primate. Changes in circulating levels in beta-endorphin were monitored during hemorrhagic shock in 18 female baboons. Plasma levels of beta-endorphin increased significantly during hemorrhagic shock and were significantly correlated with a decrease in cardiac output (P less than 0.05). Single bolus administration of the opiate receptor antagonist naloxone (2 or 5 mg/kg) produced a transient but significant improvement in cardiac output (P less than 0.05) and mean arterial pressure (P less than 0.05). Hemodynamic improvement was maintained with a constant infusion of naloxone. Opiate receptor blockade with the longer acting antagonist naltrexone (2 or 5 mg/kg) significantly increased mean arterial pressure (MAP; P less than 0.05), and CO (P less than 0.05), and decreased heart rate. Our results suggest that the baboon is an excellent model for the study of hemorrhagic shock and provide further evidence for endogenous opiate involvement in the cardiovascular pathophysiology of hemorrhagic shock.