Effect of chronic administration of morphine on primary immune response in mice

Immunomodulatory effects of pharmaceutical opioids and antipyretic analgesics: Mechanisms and relevance to infection

Understanding how pharmaceutical opioids and antipyretic analgesics interact with the immune system potentially has major clinical implications for management of patients with infectious diseases and surgical and critical care patients. An electronic search was carried out on MEDLINE, EMBASE, PsycINFO, CENTRAL and the Cochrane library to identify reports describing the immunomodulatory effects of opioid analgesics and antipyretic analgesics, and their effects in infectious diseases. In adaptive immunity, nonsteroidal anti-inflammatory drugs have divergent effects: augmenting cell-mediated immunity but inhibiting humoral immunity. Nonsteroidal anti-inflammatory drugs have demonstrated a beneficial role in Mycobacterium tuberculosis infection and histoplasmosis in animals, and may be plausible adjuvants to antimicrobial agents in these diseases. There is a need to evaluate these findings rigorously in human clinical trials. There is preliminary evidence demonstrating antiviral effects of indomethacin in SARS CoV-2 in vitro; however, uncertainty regarding its clinical benefit in humans needs to be resolved in large clinical trials. Certain opioid analgesics are associated with immunosuppressive effects, with a developing understanding that fentanyl, morphine, methadone and buprenorphine suppress innate immunity, whilst having diverse effects on adaptive immunity. Morphine suppresses key cells of the innate immunity and is associated with greater risk of infection in the postsurgical setting. Efforts are needed to achieve adequate analgesia whilst avoiding suppression of the innate immunity in the immediate postoperative period caused by certain opioids, particularly in cancer surgery.

Systemic morphine treatment derails normal uterine receptivity, leading to embryo implantation failure in mice

Morphine is the oldest worldwide well-known opioid agonist used for pain treatment in clinic, and its illicit use is often associated with adverse pregnancy outcomes in humans. Because of recent dramatic increases in nonmedicinal morphine abuse, one emerging issue is the further revelation of the dark side of illicit opioid uses, particularly in early pregnancy events. In this respect, we have demonstrated that opioid signaling is functionally operative during preimplantation embryo development in mice. However, the pathophysiological significance of the opioid system on uterine functions at peri-implantation remained elusive. In the present study, we demonstrated that opioid receptors were spatiotemporally expressed in the uterus during the peri-implantation period. Employing a pharmacological approach combined with embryo transfer experiments, we further observed that although systemic morphine treatment exerts no apparent adverse influence on preimplantation ovarian secretion of progesterone and estrogen, this aberrant activation of opioid signaling by morphine induces impaired luminal epithelial differentiation, decreased stromal cell proliferation, and poor angiogenesis, and thus hampers uterine receptivity and embryo implantation. These novel findings add a new line of evidence to better understand the causes for obvious adverse effects of opioid abuse on pregnancy success in women.

Injecting drugs of abuse and immunity: implications for HIV vaccine testing and efficacy

The recreational use of legal and illegal drugs has significant effects on immune responses and can potentially modulate susceptibility to infection by a number of pathogens. A number of agents including cannabinoids (marijuana), cocaine opiates, amphetamines, nicotine and alcohol were demonstrated to have potentially adverse effects on the susceptibility to infections, mediated most likely, by adverse effects on immunity. As such, these drugs of abuse could have significant and potentially adverse effects on the vaccination efficacy of a number of vaccines currently on the market and on potential experimental vaccines currently in the pipeline. This review will present an overview on how drugs of abuse potentially impacts immune responses and vaccination efficacy. The emphasis of this review will be the effects of opiate abuse, as exemplified by injecting/intravenous drug users (IDU), on HIV/AIDS and its potential impact on vaccine efficacy trials against this devastating infection/syndrome.

Opioid receptors and signaling on cells from the immune system

This review discusses the criteria for determining whether a binding site or functional response is directly mediated by either the mu, delta, or kappa opioid receptors. In 1988, Sibinga and Goldstein published the first review that addressed whether cells from the immune system express opioid receptors. The criteria that they used, namely, structure-activity relationships, stereoselectivity, dose- and concentration-dependence, and saturability are still relevant criteria today for determining if an immunological response is mediated by either the mu, delta or kappa opioid receptors. Radioligand receptor binding studies and functional studies that clearly show the presence of an opioid receptor on immunocytes are presented. Selective agonists and antagonists for the mu, delta, and kappa opioid receptors are discussed, and the need for their use in experiments is emphasized. Conditions used in functional assays are very important. Receptor desensitization and downregulation occur within minutes after the application of an agonist. However, many immunological assays are applying an agonist for days before measuring an immunological effect. The results obtained may reflect changes that are results of receptor desensitization and/or downregulation instead of changes that are observed with acute activation of the receptor. The future of receptor pharmacology lies in the crosstalk and dimerization of G protein-coupled receptors. In transfected systems, opioid receptors have been shown to dimerize with chemokine and cannabinoid receptors, resulting in crosstalk between different types of receptors.

Multiple ways that drug abuse might influence AIDS progression: clues from a monkey model

Whether opiates and other drugs of abuse affect AIDS progression has been an unresolved issue for two decades. Credible evidence has suggested that opiates may exacerbate, retard or have 'no effect' on progression of AIDS. Differences may exist in AIDS-progression outcomes after opiate exposures that relate to neural versus, strictly, somatic AIDS; but it is also likely that conditional variables inherent to drug dependency and the nature of the infectious agents involved allow for differing outcomes. Data from epidemiological studies, and from in vitro and basic immunological studies regarding opiate effects on AIDS progression must be interpreted in light of the conditionality of opiate effects. Caution is sounded, also, about interpreting common depressive immunological effects of opiates as indicators of influence over AIDS progression. Current evidence from the monkey model of AIDS indicates that opiates can, under certain defined conditions, retard AIDS progression. The clinical relevance of these data remains to be defined. Importantly, such data imply that opioids and the endogenous opioid system may represent therapeutic tools and targets for altering AIDS progression.

A retrospective study of the association between haematological and biochemical parameters and morphine intolerance in patients with cancer pain

BACKGROUND

Morphine is the strong opioid of choice for the treatment of moderate to severe cancer pain according to guidelines of the World Health Organization (WHO). However, a minority of patients do not receive the desired analgesic effect or suffer intolerable side effects from morphine, and are switched to alternative opioids.

METHODS

The aim of this retrospective study was to identify factors that might be associated with morphine intolerance. Data were analysed from 100 controls who tolerated morphine and 77 patients who were switched to an alternative opioid. We investigated whether currently logged data could fully explain the need to switch. Demographic details, cancer type (histological diagnosis) and markers related to organ function were included in an analysis of biochemical and haematological parameters.

RESULTS

Patients over 78 years (P = 0.03), or with a high white cell (P = 0.002) or high platelet count (P = 0.003), were more likely to switch. Although our numbers were small, patients with severe organ impairment were more likely to switch. However, a model including white cell count, platelet count, age, serum albumin and alkaline phosphatase, accurately separated switchers and controls in only 68% of cases. There was no significant difference between the two groups in terms of the numbers of patients having cytotoxic drugs in the two weeks prior to the haematological and biochemical analysis. Similarly, there were no significant differences in histological diagnoses between groups.

CONCLUSIONS

The white cell count was the strongest single effect observed and, as such, warrants further investigation. Further studies are needed in order to accurately define a model that will predict those patients likely to be intolerant of morphine.

Morphine-induced enhancement in the granulocyte response to thioglycollate administration in the rat

The present study determined the pharmacological effects of acute morphine treatment on the granulocyte phase of the peritoneal inflammatory response to thioglycollate (TG) in rats. Dual-color flow cytometry using anti-CD11b/c-PE mAb in combination with HIS48-FITC mAb allowed for the determination of morphine's effects on 4 inflammatory cell subsets: CD11b/c(+)HIS48med granulocytes; CD11b/c(hi)HIS48neg/lo activated macrophages; CD11b/c(-)HIS48(-) lymphocytes; and CD11b/c(+)HIS48hi cells (a monocyte/macrophage and granulocyte subset). Morphine produced a dose-dependent increase in a select subset of inflammatory peritoneal cells, the CD11b/c(+)HIS48med granulocytes. The effect of morphine was time-dependent, with significant effects first apparent at 4 hr after TG, but the administration of morphine 1 hr before or simultaneously with TG produced a similar increase in CD11b/c(+)HIS48med granulocytes. Naltrexone completely antagonized the morphine-induced increase in CD11b/c(+)HIS48med granulocytes. Collectively, these studies show that a single administration of morphine produces a time-dependent, dose-dependent, opioid receptor-mediated enhancement in the peritoneal granulocyte response to TG.

Morphine-induced macrophage apoptosis modulates migration of macrophages: use of in vitro model of urinary tract infection

BACKGROUND

Morphine has been reported to alter immune function. Morphine-induced macrophage apoptosis has been shown to contribute to altered immune status in an opiate milieu. We studied the effect of morphine-induced macrophage apoptosis on the migration of macrophages. Because urinary tract infection (UTI) is one of the commonest infections to evoke an inflammatory response; i.e., migration of neutrophils and monocytes to the site of infection, we used an in vitro model of UTI to test our hypothesis.

MATERIALS AND METHODS

We carried out both in vivo and in vitro studies. Mice of the FVB/N strain were treated with morphine for short (three doses, 24 hours) and long (11 doses, 96 hours) durations, and their bone marrow cells were isolated. In addition, apoptotic macrophages were prepared by heat treatment. To simulate the in vitro model of UTI, E. coli-activated tubular cell (TC)-conditioned medium containing transforming growth factor-beta (TGF-beta) and macrophage-monocyte chemoattractant protein-1 (MCP-1) was used to test migration of macrophages across a filter in a modified Boyden chamber. In addition, migration of macrophages into the peritoneal cavity was evaluated in both control and morphine-treated states. The effect of morphine on apoptosis as well as migration was studied in murine macrophages and bone marrow cells.

RESULTS

Morphine not only promoted apoptosis of bone marrow cells (20% apoptotic cells) but also inhibited their migration across the filter. Control cells showed minimal apoptosis but displayed greater migration. Similarly, heat-treated (apoptotic) cells showed minimal migration. In peritoneal macrophage studies, morphine treatment retarded migration.

CONCLUSION

Morphine inhibits macrophage migration both in vivo and in vitro. This attenuated transmigration of macrophages seems to be secondary to the apoptotic effect of morphine.

Phenotypic and functional assessments of immune status in the rat spleen following acute heroin treatment

Heroin use is associated with an increased incidence of several types of infections, including HIV. Yet few studies have assessed whether heroin produces pharmacological alterations of immune status that might contribute to the increased rate of infections amongst heroin users. The present study investigated whether a single administration of heroin to rats produces dose-dependent alterations in functional measures of immune status and in the distribution of leukocyte subsets in the spleen. The results showed that heroin produces a dose-dependent, naltrexone-reversible suppression of the concanavalin A-stimulated proliferation of T cells, lipopolysaccharide-stimulated proliferation of B cells, production of interferon-gamma and cytotoxicity of natural killer (NK) cells in the spleen. Heroin's suppressive effect on NK cell activity results in part from a heroin-induced decrease in the relative number of NKR-P1A(hi) CD3- NK cells in the spleen. Heroin also decreases the percent of a splenic granulocyte subset, the CD11b/c+ HIS48(hi) cells, whose function currently is unknown. In contrast, heroin does not alter relative numbers of CD4+ CD3+ T cells, CD8+ CD3+ T cells, CD45+ B cells, NKR-P1A(lo) CD3+ T cells, CD11b/c+ ED1+ (or CD11b/c+ HIS48-) monocytes/macrophages or CD11b/c+ ED1- (or CD11b/c+ HIS48+) total granulocytes in the spleen. Collectively, these findings demonstrate that heroin produces pharmacological effects on functional and phenotypic measures of immune status.

Morphine synergizes with lipopolysaccharide in a chronic endotoxemia model

Emergent or elective surgical procedures may be complicated by sepsis, resulting in critical illness that can lead to organ failure and death. The opioid drug, morphine is widely used to alleviate pain in post-surgical patients; however, it is well documented that chronic treatment of mice with morphine affects the proliferation, differentiation and function of immune cells. Thus, morphine might be expected to exacerbate the effects of sepsis, which also compromises the immune system. To test this notion, we investigated the effect on several immune functions of a clinical dose of morphine (4 mg/kg) superimposed upon a lipopolysaccharide (LPS)-induced infection model. Our results show that this relatively low dose of morphine, though generally having no effects on immune parameters by itself, significantly augmented LPS responses. A clinical dose of morphine (4 mg/kg body weight) superimposed upon an animal model of sepsis resulted in a significant increase in mortality at 48 h. In the absence of the drug, most septic animals died after 96 h. Phenotypic responses such as, decreased thymic cellularity, compromised mitogenic response and inhibition of IL-2 synthesis that are evident at 48-72 h after LPS injection appear as early as 24 h in animals that receive morphine in addition to LPS. In addition, our results show that in T cells there is a shift from TH1 type cytokine elaboration to a TH2 type cytokine elaboration in animals that receive both LPS and morphine.

Morphine alters macrophage and lymphocyte populations in the spleen and peritoneal cavity

We have previously shown that subcutaneous implantation of a 75 mg morphine pellet results in suppression of the ability of murine splenocytes to mount an antibody response to sheep red blood cells, due in part to a reduction of macrophage function. The present studies used flow cytometry to examine whether the decrement in macrophage function in the spleens of morphine-treated mice results from a reduction in macrophage numbers. Parallel analysis was carried out on non-elicited peritoneal cells. In the spleen, morphine resulted in a reduction in the relative proportion of macrophages and B-cells, with a concomitant increase in the proportion of T-cells. Alteration in the ratio of CD4+ to CD8+ T-cells was not observed. In contrast, in the peritoneal cavity, morphine increased the number of macrophages and reduced the number of B-cells. Naltrexone blocked all of the changes in cellular composition. These results support the conclusion that an important mechanism in the immunosuppression seen in the spleens of mice implanted with morphine pellets is a differential reduction in the number of macrophages and B-cells as compared with T-cells. Further, these studies show that subsets of cells of the immune system are differentially affected by morphine in different anatomical compartments.

Nutritional supplementation of nucleotides restores opioid CNS-mediated phenomena in mice

Previous experiments have demonstrated that suppression of immune function by either cyclosporin A or by a nucleotide free (NF) diet results in attenuation of morphine withdrawal symptoms in mice suggesting that immune status impacts CNS opioid-related phenomena. The present study elaborates on these initial findings by examining the effects of repletion of the NF diet with nucleotides or their precursors on opiate withdrawal. Female Balb/c mice were divided into six groups: a control group (C) given a standard lab chow diet and five experimental groups each given one of the following diets: a nucleotide free diet (NF); the NF supplemented with 0.25% RNA (NFR 0.25); the NF supplemented with 2.5% RNA (NFR 2.5) the NF supplemented with 0.06% uracil (NFU 0.06); the NF supplemented with 0.6% uracil (NFU 0.6). The mice were made morphine dependent by subcutaneous implantation of morphine pellets. Seventy-two hours after morphine pellet implantation, withdrawal was precipitated with naloxone (2 mg/kg). The mice were then observed and two indicators of withdrawal scored: jumping and diarrhea. The NF, NFR 0.25, NFR 2.5 and NFU 0.06 groups demonstrated significantly attenuation of the withdrawal signs relative to control animals. The NFU 0.6 group, however, had withdrawal scores restored to near control levels for both jumping and diarrhea. This suggests that nucleotides, particularly uracil, may play an important role in the immune-to-brain signaling pathway.

Opioid and benzodiazepine tolerance and dependence: application of theory to critical care practice

Critical care clinicians frequently manage patient pain and agitation and promote ventilator stability through use of opioids and benzodiazepines. Often, doses of these drugs must be increased considerably over time as they lose their effectiveness-an indication of drug tolerance. Furthermore, patients can experience negative physiologic responses to withdrawal of these drugs-an indication of drug dependence. Withdrawal symptoms due to abrupt discontinuation of drug therapy can be profound and dangerous. It is important that clinicians understand the mechanisms of drug therapies and their potential negative sequelae. The purpose of this article is to present physiologic theories of opioid and benzodiazepine actions, as well as drug tolerance and dependence, as a basis of knowledge for clinical practice. A clinical scenario of an intensive care unit patient is presented, and a care plan is offered, to provide guidance to practitioners who care for patients experiencing the consequences of long-term opioid and benzodiazepine use.

Role of prolactin in the modulation of NK and LAK cell activity after short- or long-term morphine administration in neoplastic patients

In a previous work we demonstrated that chronic in vivo antalgic therapy of cancer patients with morphine reduced the endogenous cytotoxic activity of natural killer (NK) cells, while increasing the development of lymphokine activated killer (LAK) cell cytotoxicity. In order to investigate the mechanisms by which morphine affects NK and LAK cell function further, we evaluated the modulation exerted by short- or long-term morphine administration on either NK/LAK cell cytotoxicities or plasma levels of prolactin (PRL) and other immunomodulating neurohormones. An intravenous morphine injection (10 mg) significantly increased the plasma levels of PRL, reduced the cytotoxic activity of NK cells, and increased the development of LAK cell activity 30 min after drug injection in neoplastic patients. The administration of bromocriptine before the injection of morphine prevented both PRL augmentation and the increase in LAK cell activation, although it did not prevent the inhibition of NK cytotoxicity. The chronic oral administration of morphine (90 +/- 30 mg/day for 1 month) also resulted in higher PRL levels; the NK and LAK cell activities were, respectively, lower than or higher than those found in neoplastic patients untreated with morphine. The plasma levels of thyrotropin (TSH), adrenocorticotropic hormone (ACTH) and cortisol were not significantly modified in either short- or long-term experiments. The absolute number and the percentages of lymphocyte populations, as well as the percentage of IL-2 receptors, were not modified after short-term morphine administration whereas little changes of T lymphocyte populations and NK cell number were observed after oral treatment with morphine. In vitro morphine did not affect the development of LAK cell activity. In conclusion, our findings indicate that morphine reduces NK cytotoxicity and increases the development of LAK cell cytotoxicity after short- and long-term administration. The effect of morphine on LAK cell activation but not on NK cell reduction is related to the modulation of PRL levels determined by the opioid drug.

Positive and negative immunomodulation by opioid peptides

The data that follow review part of the existing evidence concerning the neuroimmune functions mediated by opioid peptides, with particular regard to dual immunomodulatory effects. Limited references to substances other than opioid peptides are included, mainly to emphasize the possible similarities in the mediation of neuroimmune interactions by different informational substances, while the interactions directed from the immune to the nervous system have deliberately been omitted.

Immunotoxicological screening of morphine and methadone in an extended 28 day study in rats

Drug addicts are prone to infection with viruses including hepatitis-B and HIV. Besides indirect effects as a consequence of lifestyle, heroin and methadone may also enhance the risk of infections by a direct immunotoxic effect affecting resistance. In addition to general toxicological screening, we therefore performed a screening for potential immunotoxicity of morphine and methadone. Rats treated orally with different dosages of morphine or methadone for 6 weeks showed only a minor effect of overt toxicity on liver and spleen at the high dose, whereas at lower doses an increase in the relative weight of the mesenteric lymph nodes and an increase in cell density in the medullary cords were observed histopathologically, indicating a specific effect on humoral immunity. This specific immunotoxic effect was corroborated by an increased IgG concentration in serum (significant for the methadone-treated group). Further immunotoxicological research is needed aimed at revealing the potential risk of opiate use with respect to immune function. In conclusion, the present paper showed the toxicological profile of morphine and methadone in an extended 28 day subchronic study. Specific immunotoxicological effects were observed at doses where no effects were seen in routine toxicological evaluation, suggesting that the immune system is sensitive to opiates.

Suppression of immune parameters in animal models of morphine dependence

Implantation of pellets containing 75 mg of morphine induced short term (4 day) morphine dependence and markedly reduced total number of spleen cells of BALB/c mice, without affecting total body or liver weight. Polyclonal responses induced by anti-CD3 antibodies, Concanavalin A or Escherichia coli lipopolysaccharide in the remaining spleen cells of morphine-treated mice were also inhibited. Cytofluorimetric analysis indicated that the proportion of major functional lymphocyte populations (Ig+, CD3+, CD4+ and CD8+ lymphocytes) were not significantly changed in the spleen from morphine-dependent mice. Furthermore, expression levels of surface Ig, CD3, CD4, and CD8, were similar in spleen cells from control or morphine-treated mice. So, morphine dependence in BALB/c mice under these controlled conditions results in a specific defect in lymphoid cell number and function, with no incidence on body weight or particular lymphocyte subsets.

Opioid receptor-mediated suppression of humoral immune response in vivo and in vitro: involvement of kappa opioid receptors

The selective kappa opioid receptor agonist MR 2034 exerted pronounced suppression of plaque-forming cell (PFC) response following intraperitoneal (i.p.) administration in the rat. Pretreatment with preferential kappa and mu opioid receptor antagonists MR 2266 and naloxone, respectively, revealed that this effect was mediated mainly by kappa, and to a low extent by mu opioid receptors. Intracerebroventricular (i.c.v.) administration of quaternary naltrexone (QNtx) moderately attenuated, whereas i.p. given QNtx completely prevented the suppressive effect of MR 2034, suggesting a peripheral mechanism of action, and only minor involvement of brain opioid receptors. MR 2034 markedly decreased the PFC response of spleen cells obtained from in vivo immunized rats, treated in vitro with the opiate. The immunosuppressive action of MR 2034 in vitro was completely and partially blocked by equimolar concentrations of MR 2266 and naloxone, respectively. Antagonists alone produced stimulation of PFC following i.p. administration in the rat, but did not affect PFC response upon in vitro treatment. These results suggest that peripheral kappa opioid receptors down-regulate primary humoral immune response in the rat, and that this effect may be produced by direct interference with plasma cell activity.

Immunologic analyses of peripheral leukocytes from workers at an ethical narcotics manufacturing facility

Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds. We have previously reported opiate-specific IgG antibodies, positive epicutaneous tests, and pulmonary function decrements in workers exposed occupationally to opiates. In the present work, we extended these findings to investigate the effect of occupational opiate exposure on lymphocyte subpopulations and mitogen-induced lymphoblastogenesis. Thirty-three opiate-exposed workers and 8 nonexposed control workers were evaluated for lymphocyte subpopulation absolute numbers and percentages, by evaluating cell surface antigen expression with flow cytometry. A complete blood count with differential, common clinical chemistry parameters, and serum immunoglobulin levels were also evaluated. Opiate-exposed workers showed significantly (p < .05) increased absolute numbers and percentages of HLA-DR+ cells (MHC class II histocompatibility antigen), significantly (p < .01) decreased percentages of T helper-inducer (CD4+) cells, and significantly (p < .05) decreased numbers of basophils, compared with nonexposed opiate workers from the same factory. A trend toward reduction in the T helper-inducer (CD4+)/T cytotoxic-suppressor (CD8+) lymphocyte ratio was also evident. There was also a significant decrease in lymphocyte activity stimulated by pokeweed mitogen (p < .05) in opiate-exposed workers. These data indicate that occupational opiate exposure may change the number and types of circulating peripheral blood leukocytes, or alternatively, alter the expression of receptors on the surface of these cells. In addition, occupational opiate exposure appears to decrease the sensitivity of B-cells to pokeweed mitogen stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrophage functions in drugs of abuse-treated mice

The in vivo effect of morphine, methadone and cocaine on murine peritoneal macrophage-mediated cytostasis and macrophage supernatant mediated cytostasis was investigated. In addition, the activity of drugs of abuse was studied on IL-1 alpha and TNF production by activated murine macrophages. A highly depressive effect on macrophage-mediated cytostatic activity and a decrease of IL-1 alpha and TNF levels were found in the supernatants of activated macrophages observed in morphine- and cocaine-treated mice. Conversely, a significant impairment of macrophage functions was not observed in methadone-treated mice. Our results suggest that the inhibition of macrophage defensive functions caused by drugs of abuse may be an important cofactor in the pathogenesis of infectious diseases.

Effect of total parenteral nutrition plus morphine on bacterial translocation in rats

OBJECTIVE

This study tested the hypothesis that gut stasis induced by parenteral morphine sulfate (MS) leads to enhanced bacterial translocation in rats on total parenteral nutrition (TPN).

SUMMARY BACKGROUND DATA

TPN and MS are common adjuncts in the care of critically ill patients. TPN is known to provoke a variable degree of translocation. MS induces gut stasis with an accompanying bacterial overgrowth. The effect of these two treatments in combination on translocation is not known.

METHODS

Rats were provided with central and subcutaneous lines for the continuous infusion of nutrients and drugs, respectively. Intestinal transit was assessed by the caudal movement of a fluorescent marker intubated into the proximal duodenum. Quantitative bacteriology was carried out from various segments of the gut and from ileocecal mesenteric lymph nodes (MLN), spleen, liver, and systemic blood obtained by cardia puncture on sacrifice at 96 hours.

RESULTS

Transit was unchanged by TPN alone but prolonged when given in combination with MS. Bacterial overgrowth was also enhanced by MS and increased the bacterial translocation to MLN from 50% of animals with TPN, to 100% in those receiving both TPN and MS; the colony-forming units per MLN increased from 33 +/- 14 with TPN alone to 2079 +/- 811 (STD) with TPN plus MS. Furthermore, no bacteria were found at systemic sites with TPN alone, but in 93.3% of animals receiving TPN and MS. In a subgroup of rates provided with glutamine in TPN, the TPN plus MS effects on translocation were not reversed.

CONCLUSIONS

These observations demonstrate the important role that morphine plays in promoting translocation, presumably by disrupting fasting motility and enhancing bacterial overgrowth.

Locus ceruleus and immunity. III. Compromised immune function (antibody production, hypersensitivity skin reactions and experimental allergic encephalomyelitis) in rats with lesioned locus ceruleus is restored by magnetic fields applied to the brain

This study deals with the relationship between the immunosuppression induced by electrolytic lesions placed into the nucleus locus cerules and the immunopotentiation produced by micromagnets implanted to the parietal area of the skull. The following groups of rats were set up: LC, rats with lesioned locus ceruleus; ShL, sham-lesioned animals bearing non-magnetic beads in the brain parietal region; M, rats with micromagnets of 60 mT influx density in the parietal part of the skull; LCM, animals with impaired locus ceruleus and magnetic beads placed in the parietal area of the skull; and IC, intact control rats. Animals of all groups were tested for plaque-forming cell response, circulating antibodies to sheep red blood cells and bovine serum albumin, Arthus and delayed hypersensitivity skin reactions to bovine serum albumin and old tuberculin, and experimental allergic encephalomyelitis. In LC-rats, humoral and cell-mediated immune reactions were compromised. On the other hand, immune responses in M-rats were significantly potentiated. In LCM-rats, however, the immunosuppression induced by destruction of the locus ceruleus was abrogated by prolonged exposure of the brain parietal region to the magnetic fields, i.e. immune reactivity of LCM-rats was quite similar to that of control IC- and ShL-animals. Several mechanisms may account for the immunomodulating effects produced by lesioning of the locus ceruleus and exposure of the brain to magnetic fields. Noradrenergic, serotoninergic, dopaminergic and peptidergic neurotransmitters, as well as growth hormones and immunopeptides, produced within the central nervous system or elsewhere, may be implicated as necessary for the interactions among the brain, immune apparatus and magnetic fields.

Differential effects of morphine and naltrexone on the antibody response in various mouse strains

Morphine treatment has been shown to suppress several immunologic parameters. In this study, we examined the effects of morphine pellet implantation in vivo on the primary antibody response measured in vitro in various mouse strains. Effects of mouse strain and sex on morphine-induced suppression of the plaque-forming cell response, as well as spleen weight and mortality were determined. Morphine suppressed the primary antibody response in C3HeB/FeJ, C3H/HeJ and C57Bl/6 mice, while Balb/cByJ and the mu-receptor-deficient strain CxBk/ByJ mice were not affected. There was no difference in the response to morphine between male and female C3HeB/FeJ mice. Naltrexone reversed the morphine-induced suppression in the C3H strains, but not in C57Bl/6 mice. In addition, naltrexone caused significant mortality in Balb/cByJ mice. Spleen weight was decreased by morphine treatment in all the strains, but only the C3H strains were sensitive to the lethal effects of morphine. Thus, immune suppression did not correlate with splenic atrophy or mortality. The strain differences in response to chronic morphine and naltrexone treatment suggest that morphine may be acting through both opioid and non-classical opioid (e.g., not blocked by naltrexone) mechanisms.

AIDS, drugs of abuse and the immune system: a complex immunotoxicological network

Two of the most interesting questions often asked about AIDS is why many people do not become immunodeficient or get complicating disease when first infected with Human Immunodeficiency Virus (HIV) and what are the "risk factors" making some individuals more susceptible to the disease. A large majority of people with AIDS have a well established history of drug and alcohol abuse. Both drugs of abuse and alcohol have immunotoxic properties as evidenced by a number of studies. These include marked changes in the cellular, humoral and other components of the immune defense mechanism. Such a compromise of the immune system can render it susceptible to the development of AIDS after HIV infection. This paper reviews the evidence suggesting possible links between substance abuse and its immunotoxicology, and their possible roles in the pathogenesis of AIDS.

Magnetic fields, brain and immunity: effect on humoral and cell-mediated immune responses

Magnetic fields (MF) can influence biological systems in a wide range of animal species and humans. We report here on the influence of static MF, locally applied to the brain area, on immune system performances in the rat. In the first series of experiments two AKMA micromagnets (M) with the influx density of 600 Gauss were bilaterally implanted (with "N" polarity facing the cranial bones) and fixed to the skull posterior to the fronto-parietal suture (parietal brain exposure). Rats implanted with iron beads (I) and sham-operated (SO) rats served as controls. Animals were exposed to MF or I during different periods of time before and after immunization with several soluble or cellular antigens. We report here on the in vivo immunoregulating effects of centrally applied MF on plaque-forming cell (PFC) response, local hypersensitivity skin reactions and experimental allergic encephalomyelitis. The selective influence of MF applied to different brain regions on PFC response was evaluated, as well. For this purpose, two M were bilaterally implanted in the area of (a) frontal, (b) parietal and (c) occipital brain regions. Rats were under the influence of MF for 20 days before and 4 days after immunization with sheep red blood cells. Groups of nonimmunized rats were exposed for 14, 24 and 34 days to parietally implanted M or I, and the number of peripheral blood CD4+ and CD8+ cells determined by mouse anti-rat W3/25 and MRC OX 8 monoclonal antibodies. The results show an overall in vivo immunopotentiation of humoral and cell-mediated immune responses in rats exposed to MF. Furthermore, these immunomodulating effects of centrally applied MF depend on at least two basic parameters, time of exposure and brain region exposed. The highest immune performance was obtained after exposure of the occipital brain region for a total period of 24 days. The results provide further evidence of the complex interrelationship between the environment, the central nervous system and the immune system.

Evaluation of NK and LAK cell activities in neoplastic patients during treatment with morphine

The cytotoxic activity of Natural Killer (NK) and Lymphokine Activated Killer (LAK) cells in neoplastic patients with or without antalgic treatment was studied. NK cell activity was found reduced in untreated neoplastic patients when compared to healthy subjects. The atalgic treatment with morphine (orally or intrathecally administered) was able to significantly reduce the mean values of NK cell activity found in cancer patients. In three patients the cytotoxicity of NK cells significantly decreased during transfer from oral to intrathecal administration of morphine. In contrast to the NK cell function, the development of LAK cell activity significantly increased in neoplastic patients when compared to healthy controls. Further increments were obtained during treatment with morphine. The oral treatment with morphine was able to determine a higher induction of LAK cells than the intrathecal administration of the drug. Besides providing new knowledge on the effect of morphine on immune system our findings suggest that, in order to include neoplastic patients in clinical trials of adoptive immunotherapy with LAK cells and interleukin-2 (IL-2), the antalgic therapy with oral administration of morphine may represent a better solution than the intrathecal administration of the drug.

Morphine-induced transactivation of HIV-1 LTR in human neuroblastoma cells

Infection by human immunodeficiency virus (HIV) is followed in many cases by a clinically quiescent or latent phase that appears to continue as long as host antiviral defense is intact. This has raised the possibility that certain host susceptibility factors (i.e., environmental cofactors) might influence the progression of the disease. In this study we demonstrate that morphine can function to activate HIV/LTR-CAT fusion gene (HIV-long terminal repeat-chloramphenicol acetyltransferase) when transfected into undifferentiated human SH-SY5Y neuroblastoma cells. The stimulatory effect of morphine is amplified in SH-SY5Y cells that have been induced to differentiate first with phorbol 12-myristate 13-acetate (PMA) and is much less in cells differentiated with retinoic acid (RA). Morphine does not appreciably activate HIV/LTR-CAT expression in human MOLT-3 and other T cells. Morphine activation of HIV/LTR-CAT in the SH-SY5Y cells is not reversible by naltrexone and appears to involve a Fos/Jun signaling system. Our results suggest that narcotics such as morphine may lead to activation of latent HIV infection. This may be particularly important in tissues, such as brain, which can host latent HIV infection and which is uniquely damaged in patients with acquired immunodeficiency syndrome (AIDS) as evidenced by neuronal degeneration and dementia. We also predict that these findings may have important implications for the pathogenesis of AIDS, particularly in opiate drug abusers.

Morphine inhibition of lymphocyte activity is mediated by an opioid dependent mechanism

The effects of acutely-administered morphine on mitogen stimulated lymphocyte proliferation and natural killer cell cytolytic activity were investigated. Two hours after a subcutaneous injection of morphine (25 mg/kg), blood lymphocyte proliferation was found to be 70% depressed, compared to saline-injected controls. This effect was partially antagonized in animals pretreated with naltrexone (10 mg/kg) and was present only in blood lymphocytes, since proliferative responses of splenic lymphocytes were not significantly altered. The administration of morphine, however, did result in a 30-40% inhibition of cytolytic activity of natural killer cells, which was completely antagonized in naltrexone-pretreated animals. Naltrexone alone was found to have no effect on either proliferation of blood and splenic lymphocytes or the cytolytic activity of splenic lymphocytes. Although naltrexone had no effect on the activity of lymphocytes, animals treated with either naltrexone or morphine alone, or their combination, had 4- to 8-fold increases in corticosterone in plasma. These results demonstrate that the effect of morphine on immune cells was dependent on the tissue source of lymphocytes. Furthermore, the suppression of blood lymphocyte proliferation and splenic cytolytic activity of natural killer cells by morphine was opiate receptor-mediated, as indicated by the reversibility by naltrexone of the observed effects of morphine. Finally, the accompanying increase in circulating levels of corticosterone most likely did not contribute to these effects.

Antibodies to morphine in workers exposed to opiates at a narcotics manufacturing facility and evidence for similar antibodies in heroin abusers

According to the International Narcotics Control Board, over 45,000 kg of morphine and 54,000 kg of codeine were ethically manufactured in 1986 at three facilities in the United States. Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds in this industry. Because there are no specific federal standards for workplace exposure to narcotic dusts, exposure-control defaults to the nuisance dust standard (10 mg/m3, as an 8 hr time-weighted average). Narcotics manufacturing workers were evaluated for anti-morphine IgG before and 10 mo. after the implementation of an improved respiratory protection program (RPP). Significantly elevated IgG levels were measured before the improved RPP (P less than 0.005). After the improved RPP, a significant reduction was observed (P less than 0.001), suggesting that specific antibody levels could be used as biomarkers of exposure. Inhibition studies showed that the antibodies were specifically directed against morphine with some cross reactivity with morphine derivatives. Preliminary results are also shown which indicate that similar anti-morphine antibodies are present in the sera of intravenous heroin abusers. Elevated levels (P less than 0.05) of anti-morphine antibodies were detected in sera from heroin abusers, providing evidence that similar antibodies may be produced from non-occupational exposure to opiates. These finding have potentially far-reaching implications for addiction research and drug testing.

Effects of cocaine and morphine on IgG production by human peripheral blood lymphocytes in vitro

Elevated serum levels of IgG are amongst the immunological abnormalities exhibited by intravenous drug addicts. We therefore addressed the hypothesis that cocaine and morphine (the major metabolite of heroin) exert a direct effect on human B cell function in vitro. Human peripheral blood mononuclear cells from normal individuals were incubated for 7 days with the T cell-dependent B cell activator pokeweed mitogen (PWM) and serial dilutions of either cocaine or morphine. At the end of this time total IgG was measured by use of a sandwich ELISA incorporating a biotin-labelled affinity-purified anti-IgG and streptavidin peroxidase. At concentrations relevant to those found in plasma, morphine and cocaine did not affect PWM-stimulated IgG synthesis in vitro. We suggest that these drugs of abuse do not directly influence human B cells, but in vivo exert immune modulatory effects via indirect mechanisms.

Comparison of propofol and midazolam for sedation in critically ill patients

101 critically ill patients admitted to five intensive-care units were allocated randomly to receive a continuous intravenous infusion of either propofol or midazolam for sedation for up to 24 h. In addition, morphine was given to provide analgesia. The mean duration of infusion was 20.2 h (range 3.0-24.5) in the propofol group and 21.3 h (4.0-47.0) in the midazolam group and infusion rates were 1.77 mg/kg/h (range 0.40-5.00) and 0.10 mg/kg/h (0.01-0.26), respectively. The infusion rates were adjusted as necessary, and the desired level of sedation was achieved easily in most patients in both groups. There were slight falls in arterial pressure, but there were no significant differences between the groups. Heart rate was lower in patients who received propofol. Some small changes occurred in biochemical and haematological variables in both groups, but they were not clinically significant. There was no indication that either drug substantially impaired adrenal steroidogenesis. When the infusion was discontinued, there was less variability in recovery of consciousness in patients who had received propofol. In a subgroup of patients, weaning from mechanical ventilation was achieved significantly faster after discontinuation of propofol than of midazolam. Propofol proved to be a satisfactory agent for sedation of these critically ill patients and compared favourably with midazolam.

The periaqueductal gray matter mediates opiate-induced immunosuppression

The periaqueductal gray matter of the mesencephalon (PAG) subserves a variety of diverse autonomic functions and also appears to be a site for opiate action in the induction of immunosuppression. Microinjections of morphine into the PAG, but not into other opiate receptor-containing neuroanatomical sites, result in a rapid suppression of natural killer (NK) cell activity. The NK cell suppression can be blocked by prior peripheral administration of the opiate antagonist naltrexone. These findings demonstrate that certain central actions of opiates that produce changes in NK cell function are mediated through opiate receptors in the PAG and identify a brain region involved in opiate regulation of immune function.

Beta-endorphin suppresses rat plaque-forming cell response by a non-opioid mechanism

The opioid peptide beta h-endorphin 1-31 inhibited the plaque-forming cell (PFC) response to sheep red blood cells when rat splenocytes, immunized in vivo, were cultured in vitro with the peptide. The opioid antagonist naloxone failed to reverse the beta h-endorphin 1-31 suppression of the PFC response. Peptide fragments of beta h-endorphin 1-31, other opioid peptides, and alkaloids had no effect on the response. These data indicate that beta h-endorphin 1-31 suppresses antibody production or secretion by a specific, non-opioid receptor on the rat splenocytes.

Methionine-enkephalin and beta-endorphin levels in spleen and thymus gland of morphine tolerant-dependent and abstinent rats

The effect of chronic administration of morphine and abrupt and naloxone-precipitated withdrawal on the levels of beta-endorphin and methionine-enkephalin in spleen, adrenals and thymus glands of Sprague-Dawley rats was determined. Rats were made tolerant to and dependent on morphine by subcutaneous implantation of 6 morphine pellets (75 mg morphine in each) during a 7-day period. The tolerant-dependent (with pellets intact) and abstinent (pellets removed 18 hours earlier) rats were sacrificed. In another group, rats with pellets intact were injected with naloxone and sacrificed 10 min later (precipitated abstinence). The weights of the tissues under any of the above treatments did not change nor did the levels of methionine-enkephalin and beta-endorphin in adrenals. The level of beta-endorphin was elevated in the spleen and thymus of morphine tolerant-dependent rats, while the levels of methionine-enkephalin in rats undergoing abrupt or naloxone-precipitated abstinence were significantly higher than in their respective placebo controls. The levels of methionine-enkephalin in the thymus gland of rats with placebo and morphine pellets left intact did not differ. It is concluded that in morphine tolerant-dependent rats the levels of beta-endorphin in spleen and thymus are elevated. During abrupt and naloxone-precipitated abstinence, the levels of methionine-enkephalin in the thymus gland are significantly elevated possibly due to an inhibition of their release. Since these opioid peptides have been implicated in immunomodulation, and alterations were seen in organs controlling immune function, the present results may be helpful in explaining altered immune function in morphine dependent and abstinent states.

Morphine-induced immunomodulation is not related to serum morphine concentrations

Morphine pellets produced atrophy of the spleen and thymus and affected mitogen-induced lymphocyte proliferation in mice as characterized by marked suppression of concanavalin A-induced blastogenesis at 48 h, and mild stimulation at 120 h. Morphine blood levels in these animals indicated that changes in the immunomodulatory effects of morphine over time were not related to dramatic shifts in circulating morphine. Enclosure of the pellet in nylon mesh did not alter blood levels or morphine-induced immunomodulation.

Opioid peptides modulate immune functions. A review

In the past few years it has become evident that neuropeptides may be direct mediators in the modulation of the immune response and the unspecific defense by the brain. Lymphocytes have been thought to have opioid receptors and to respond to opioids with an increase in blastogenesis, cytotoxicity and factor release. Lymphocytes are said to release various neuropeptides. Furthermore, there are some unexplained effects of morphine on the immune system and of the immune system on morphine withdrawal. The purpose of this paper is to review what has been previously published in this field. The well established modulation of phagocyte functions by opioids will only be scanned.

Aggravation by morphine and D-aspartic acid of pyelonephritis induced by i.v. inoculation of Staphylococcus aureus in rats

Experimental pyelonephritis was induced by intravenous inoculation of Staphylococcus aureus in homozygous Brattleboro diabetes insipidus (Hom Brattleboro DI), heterozygous Brattleboro (Het Brattleboro) and Wistar rats. One group of rats from each strain was implanted with morphine-containing pellet three days before inoculation. Another series of groups received D-aspartic acid (D-ASP) intraperitoneally, starting three days before inoculation throughout the experiments. Owing to the inhibition by morphine or D-ASP of food intake, another control group from each strain was subjected to food restriction. Pyelonephritis development on the tenth day of inoculation was evaluated by the determination of viable bacteria in urine and total kidney tissue, and pathomorphological lesions in kidney. Hom Brattleboro DI rats appeared more resistant. Morphine or D-ASP significantly increased the findings in three strains of rat.

Immunomodulation by morphine and marijuana

The immunomodulatory effects of morphine and the active components of marijuana, particularly tetrahydrocannabinol, on various aspects of the host immune parameters include alterations in humoral, cell-mediated and innate immunity. Most studies have shown immunosuppressive effects due to use of these abused substances, although there are reports that they may not produce any deleterious effect and may even enhance some aspects of host immunity. They reduce resistance to cancer growth and microbial pathogens in animals.