Leishmania donovani amastigote component-induced colony-stimulating factor production by macrophages: modulation by morphine

Nitric oxide and hormesis

This present paper provides an assessment of the occurrence of nitric oxide (NO)-induced hormetic-biphasic dose/concentration relationships in biomedical research. A substantial reporting of such NO-induced hormetic effects was identified with particular focus on wound healing, tumor promotion, and sperm biology, including mechanistic assessment and potential for translational applications. Numerous other NO-induced hormetic effects have been reported, but require more development prior to translational applications. The extensive documentation of NO-induced biphasic responses, across numerous organs (e.g., bone, cardiovascular, immune, intestine, and neuronal) and cell types, suggests that NO-induced biological activities are substantially mediated via hormetic processes. These observations are particularly important because broad areas of NO biology are constrained by the quantitative features of the hormetic response. This determines the amplitude and width of the low dose stimulation, affecting numerous biomedical implications, study design features (e.g., number of doses, dose spacing, sample sizes, statistical power), and the potential success of clinical trials.

Toxoplasma gondii: Preventive and therapeutic effects of morphine and evaluation of treatment parameters of tachyzoites and infected macrophages in vitro and in a murine model

Common medicines for the treatment of toxoplasmosis have limited efficacy and unwanted side effects. Opiates can effect both innate and cell-mediated immunity and stimulate the immune responses in different parasitic infections. In this work, preventive and therapeutic effects of morphine were evaluated on the tachyzoites of Toxoplasma gondii and infected macrophages in vitro and in a murine model. Different concentrations of morphine (0.1 and 0.01 μg/ml) were evaluated on mortality rate of T. gondii by direct counting after 3 and 24 hours. The cytotoxic and apoptotic effects of these drugs were measured by the MTT assays and flow cytometry analysis, respectively. The same procedures were assessed in T. gondii-infected macrophages. The parasite loads were determined using quantitative polymerase chain reaction (qPCR). For in vivo assessment, BALB/c mice treated with morphine before or after infection with tachyzoites. The survival rate of animals, parasite load in the spleen, and the IFN-γ and IL-4 cytokines levels were measured. Morphine was effective on tachyzoites of T. gondii and had a reverse relationship with its concentration. The results of flow cytometry showed that the toxic effects of morphine on tachyzoites after 3 hours was not statistically significant (p<0.05). Also, apoptosis in infected MQs rose with a decreasing concentration of morphine. The parasitic load in MQs treated with morphine before infection was lower than that in cells treated after infection and the differences were statistically significant (p<0.01). In mice that received morphine before infection, survival rate, parasite load and the IFN-γ level were significantly lower than in mice treated after infection (p<0.01). The results of this study have shown that morphine in the pre-treatment group had higher anti-Toxoplasma activity than morphine in post-treatment in vitro and in murine model.

Effect of morphine on Mycobacterium smegmatis infection in mice and macrophages

The immunomodulatory effects of opioids are known in various infections. However, little is known about the effects of opioids in tuberculosis (TB). In the present study, we report the effects of morphine in Mycobacterium smegmatis infection in mice and macrophages. Morphine exerted a dose-dependent suppression of infection in vivo: 50 and 100 mg/kg morphine exerted significant (P<0.05) suppression whereas 5 mg/kg morphine showed no effect. Analogous to the in vivo effects, incubation of M. smegmatis-infected mouse peritoneal macrophages with morphine (100 μM) showed significant reduction in intramacrophage CFU counts. However, morphine did not show any direct antimycobacterial activity in broth dilution assay upto 100 μM concentration. Further, morphine-induced intramacrophage killing of M. smegmatis was abrogated by naloxone and aminoguanidine indicating the involvement of opioid-receptor activation and nitric oxide production in protective effects of morphine. In conclusion, morphine suppressed the progression of experimental TB in both mice and macrophage models.

Leishmanicidal effect of LLD-3 (1), a nor-triterpene isolated from Lophanthera lactescens

Leishmanicidal activity of 6alpha, 7alpha, 15beta, 16beta, 24-pentacetoxy-22alpha-carbometoxy-21beta,22beta-epoxy-18beta-hydroxy-27,30-bisnor-3,4-secofriedela-1,20 (29)-dien-3,4 R-olide (LLD-3 (1)) isolated from Lophanthera lactescens Ducke, a member of the Malpighiaceae, was demonstrated against intramacrophage amastigote forms (IC(50) of 0.41mug/mL). The in vitro leishmanicidal effect of Glucantime, the first choice drug for leishmaniasis treatment, was increased by LLD-3 (1) association. The leishmanicidal effect of LLD-3 (1) was not due to stimulation of nitric oxide production by macrophages. LLD-3 (1) was also not cytotoxic for mouse peritoneal macrophages or B cells as assessed by the XTT and Trypan blue exclusion assays. LLD-3 (1) was unable to affect proliferation of naïve or activated B and T cells, as well as the B cells immunoglobulin synthesis. Cellularity of different tissues, liver and kidney functions were not altered in mice treated with LLD-3 (1), as well as the histology pattern of different organs. Our results add LLD-3 (1) as a potential drug candidate for treatment of leishmaniasis.

Effects of morphine during Mycobacterium tuberculosis H37Rv infection in mice

The effects of opiates in various infections are well known; however, very little is known about tuberculosis infection. Therefore, in the present study, we report for the first time, the effects of morphine during murine tuberculosis. Mice were infected intravenously with Mycobacterium tuberculosis H37Rv, administered morphine (0.1-100 mg/kg subcutaneously on day 0 and day +15) and sacrificed on day +30 for CFU enumeration in lungs and spleen. Morphine exerted maximum suppression of infection at 5 mg/kg, and sometimes completes elimination of infection; naloxone, silica and aminoguanidine blocked the protective effect of morphine. In vitro, morphine lacked direct antimycobacterial activity up to 1x10(-4) M concentration, as assessed by radiometric BACTEC method. In macrophage model of infection, morphine showed maximal killing at 1x10(-7) M concentration, the activity was blocked by naloxone and aminoguanidine. These observations suggest that morphine exerts a dose-dependent effect in murine tuberculosis, the protective effect being naloxone-reversible and may involve macrophage-mediated protective mechanisms. These results may be helpful in developing new opioid-like chemical entities against tuberculosis infection.

Morphine-induced neuroimmunomodulation in murine visceral leishmaniasis: the role(s) of cytokines and nitric oxide

Opioid modulation of host resistance to infectious diseases is well documented; however, not much is known during visceral leishmaniasis (VL). Low doses of morphine, administered subcutaneously in Leishmania donovani-infected BALB/c mice, on days 0 and +15, significantly (p < 0.05) suppressed (1 mg/kg/day) or even sterile-cleared (2 mg/kg/day) the infection; paradoxically, high doses (10 and 30 mg/kg/day) exacerbated the infection. In vitro, low concentration (1 x 10(-9) and 1 x 10(-11) M) morphine treatment of L. donovani-infected mouse peritoneal macrophages (PM), endowed them with significant (p < 0.05) leishmanicidal activity, whereas a high-concentration (1 x 10(-5) M) treatment augmented intramacrophage parasite growth. Naloxone pre-treatment of infected-mice (4 mg/kg x 2) and of infected-PM (1 x 10(-5) M), blocked only the morphine low dose/concentration-induced protective effect. The splenocytes from protected mice and morphine low concentration-treated infected-PM, elaborated significantly (p < 0.05) enhanced levels of interleukin-12, interferon-gamma, tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor and nitrite in the culture medium; a high dose/concentration suppressed their elaboration. Curiously, only morphine high dose/concentration-treated infected mice splenocytes and infected PM, produced significantly (p < 0.05) increased quantity of transforming growth factor-beta1. Aminoguanidine, significantly (p < 0.05) blocked the morphine low dose/concentration-induced protective effect, in vivo and in vitro. This first study demonstrates dose-dependent biphasic modulatory effects of morphine in L. donovani-infected mice and PM, in vitro, apparently via nitric oxide-dependent mechanisms. These results thus demonstrate the implications of opiate abuse on the efficacy assessment of antileishmanial drugs and vaccines, and on the reactivation of latent VL in areas where both drug abuse and VL are rampant.

Topical morphine for the treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a potentially disfiguring parasitic disease which is endemic in many parts of the world. The evidence for optimal treatment of CL is uncongenial. The development of a compound used for the topical treatment of CL is an attractive option for overcoming the problems of toxic and expensive currently used anti-leishmanial drugs. Easy application is another attraction of topical treatment compared to systemic therapy. Evidence is certainly about a variety of immune responses in the healing process of CL. The immune modulatory effect of morphine also has been known in clinical medicine for decades. Protection against leishmaniasis is dependent upon generation of CD4(+) helper T-cells immune response. There are some evidences that opioids could be members of the cytokine family and the regulation of immune and inflammatory responses is dependent on the functions of cytokines; therefore much effort should be placed on understanding the effect of morphine on cytokine activity. Based on a previous mentioned evidence we suggest that morphine as an immunomodulator could induce the healing process of cutaneous leishmaniasis through inducing the release of a number of cytokines.

Endogenous opiates and behavior: 2005

This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).