Immunomodulation by cocaine--a neuroendocrine mediated response

Role of the gut-brain axis in HIV and drug abuse-mediated neuroinflammation

Drug abuse and related disorders are a global public health crisis affecting millions, but to date, limited treatment options are available. Abused drugs include but are not limited to opioids, cocaine, nicotine, methamphetamine, and alcohol. Drug abuse and human immunodeficiency virus-1/acquired immune deficiency syndrome (HIV-1/AIDS) are inextricably linked. Extensive research has been done to understand the effect of prolonged drug use on neuronal signaling networks and gut microbiota. Recently, there has been rising interest in exploring the interactions between the central nervous system and the gut microbiome. This review summarizes the existing research that points toward the potential role of the gut microbiome in the pathogenesis of HIV-1-linked drug abuse and subsequent neuroinflammation and neurodegenerative disorders. Preclinical data about gut dysbiosis as a consequence of drug abuse in the context of HIV-1 has been discussed in detail, along with its implications in various neurodegenerative disorders. Understanding this interplay will help elucidate the etiology and progression of drug abuse-induced neurodegenerative disorders. This will consequently be beneficial in developing possible interventions and therapeutic options for these drug abuse-related disorders.

The Effects of Anesthetics and Perioperative Medications on Immune Function: A Narrative Review

Preclinical and clinical studies have sought to better understand the effect of anesthetic agents, both volatile and intravenous, and perioperative adjuvant medications on immune function. The immune system has evolved to incorporate both innate and adaptive components, which are delicately interwoven and essential for host defense from pathogens and malignancy. This review summarizes the complex and nuanced relationship that exists between each anesthetic agent or perioperative adjuvant medication studied and innate and adaptive immune function with resultant clinical implications. The most commonly used anesthetic agents were chosen for review including volatile agents (sevoflurane, isoflurane, desflurane, and halothane), intravenous agents (propofol, ketamine, etomidate, and dexmedetomidine), and perioperative adjuvant medications (benzodiazepines, opioids, nonsteroidal anti-inflammatory drugs [NSAIDs], and local anesthetic agents). Patients who undergo surgery experience varying combinations of the aforementioned anesthetic agents and adjuncts, depending on the type of surgery and their comorbidities. Each has unique effects on immunity, which may be more or less ideal depending on the clinical situation. Further study is needed to better understand the clinical effects of these relationships so that patient-specific strategies can be developed to improve surgical outcomes.

Cocaine enhances HIV-1 replication in CD4+ T cells by down-regulating MiR-125b

The main objective of this study was to examine effects of cocaine on HIV-1 replication in primary CD4+ T cells. Cocaine a commonly used drug among HIV-1 positive individuals serves as a cofactor for HIV-1 infection and progression to acquired immunodeficiency syndrome (AIDS). Accumulating evidence suggest that cocaine increases HIV-1 replication in cell cultures, peripheral blood mononuclear cells (PBMCs) and animal models. Intriguingly, there are no studies on cocaine-induced alterations in HIV-1 replication in primary CD4+ T cells that serve as the main targets for HIV-1 replication in vivo. In this report, we demonstrate cocaine-induced enhancement of HIV-1 replication in primary CD4+ T cells isolated from human PBMCs. To decipher a potential mechanism, we examined whether cocaine targets the innate antiviral immunity of CD4+ T cells mediated by cellular microRNAs (miRNAs). This is because recently a network of anti-HIV miRNAs in CD4+ T cells is highlighted to suppress viral replication. Our genome wide miRNA expression analysis indicated downregulation of several anti-HIV miRNAs (miR-28, miR-125b, miR-150, miR-223, and miR-382) in cocaine treated CD4+ T cells. However, our real-time quantitative PCR analysis revealed significant downregulation of miR-125b only. Our results illustrated that miR-125b knockdown enhances HIV-1 replication, whereas overexpression of miR-125b decreases HIV-1 replication in these cells. Therefore, we believe miR-125b is a key player for the cocaine induced enhancement of HIV-1 replication in CD4+ T cells. Since, miR-125b targets the 3′ UTR regions of HIV-1 transcripts and inhibits viral protein translation, our data suggest modulation of post entry steps of HIV-1 by cocaine. Given that a plethora of studies suggest that cocaine regulates HIV entry, our results implicate a potentially novel mechanism by which cocaine can increase viral replication in CD4+ T cells.

Effect of Ocimum sanctum, ascorbic acid, and verapamil on macrophage function and oxidative stress in mice exposed to cocaine

OBJECTIVE

To investigate the effect of Ocimum sanctum, ascorbic acid, and verapamil on macrophage function and oxidative stress in experimental animals exposed to cocaine.

MATERIALS AND METHODS

Mice were used in this study and were divided randomly into different groups of six animals each. They were either treated with intraperitoneal injection of saline or cocaine hydrochloride or an oral feeding of oil of Ocimum sanctum, ascorbic acid or verapamil, or both (ascorbic acid and verapamil), and were evaluated for a respiratory burst of macrophages, superoxide and nitric oxide (NO) production, estimation of TNF-alpha in the serum and supernatant of cultured macrophages, estimation of lipid peroxidation (malondialdehyde- MDA) in the serum, and superoxide dismutase activity in the erythrocytes.

RESULTS

Unstimulated respiratory burst as well as superoxide production was enhanced on treatment with cocaine and all the three drugs were found to attenuate this enhancement. The bactericidal capacity of macrophages decreased significantly on chronic cocaine exposure, as it was associated with decreased respiratory burst and superoxide production. There was a significant decrease in NO production by macrophages on chronic cocaine exposure and all the test drugs were found to restore nitrite formation to a normal level. There was an increase in the malonylodialdehyde (MDA) level and decrease in the superoxide dismutase level on chronic cocaine exposure, and all the three drugs effectively decreased the MDA level and increased superoxide dismutase level. There was an increase in serum TNF-alpha on chronic cocaine exposure, which was decreased significantly by ascorbic acid and verapamil.

CONCLUSION

O. sanctum, ascorbic acid, and verapamil were equally effective in improving the macrophage function and reducing oxidative stress. These findings suggested that O. sanctum, ascorbic acid, and verapamil attenuated acute and chronic cocaine-mediated effects.

Immunomodulation by cocaine and ketamine in postnatal rats

The abuse of cocaine (COC) in combination with ketamine (KET) among pregnant women was shown to be high. Transplacental exposure is not the only route by which a newborn may be exposed to these agents, but they can also distribute into breast milk. Chronic COC exposure is associated with immunological modulation in human and animal models. The effect of sub-chronic exposure to COC and KET alone and in combination on the developing immune system was assessed in neonatal male Sprague-Dawley (SD) rats. To simulate the route of exposure during lactation, newborn male rats were treated orally with saline, COC alone (20 mg/kg), KET alone (50 mg/kg), or KET (50 mg/kg) followed 15 min later by COC (20 mg/kg) from days 1 to 21 of life. Pups were sacrificed 30 min following the last treatment. Total circulating leukocyte and lymphocyte counts were decreased with relative neutrophilia, while spleen/body weight ratio and IgM antibody response to sheep red blood cells (SRBCs) were increased in animals treated with COC. Moreover, treatment with COC alone increased serum interleukin 10 (IL-10) concentration; however, it did not affect serum interferon gamma (IFN-gamma) concentration. On the other hand, KET treatment did not produce any significant change of any of these parameters. However, when co-administered with COC, the immunomodulatory effects of COC were prevented. COC caused a significant increase in serum corticosterone concentration that KET effectively prevented. Lack of significant change of plasma and tissue concentrations of norcocaine (NC) suggested no role for COC metabolism in COC-induced immunomodulation. However, the results of this study indicate that COC-induced immunomodulatory reactions and their prevention by KET most likely occurred through neuroendocrinal mechanisms.

IL-10 mediates sigma 1 receptor-dependent suppression of antitumor immunity

Sigma receptors are unique endoplasmic reticulum proteins that mediate signaling for a variety of drugs. We determined the effect of sigma(1) receptor agonists on immune responses in a syngeneic lung cancer model. Sigma(1) receptor agonists, including cocaine, up-regulated splenocyte IL-10 mRNA and protein production in vitro in a sigma receptor-dependent, pertussis toxin-sensitive manner. In vivo, sigma(1) receptor agonists promoted tumor growth and induced IL-10 at the tumor site. Increased tumor growth was prevented by administration of specific Abs to IL-10 or by administration of specific sigma(1) receptor antagonists. We report that sigma(1) receptor ligands, including cocaine, augment tumor growth through an IL-10 dependent mechanism.

Cardiovascular disorders associated with cocaine use: myths and truths

Cocaine produces a pattern of cardiovascular responses that are associated with apparent myocardial ischemia, arrhythmias, and other life-threatening complications in some individuals. Despite recent efforts to better understand the causes of cocaine-induced cardiovascular dysfunction, there remain a number of unanswered questions regarding the specific mechanisms by which cocaine elicits hemodynamic responses. This review will describe the actions of cocaine on the cardiovascular system and the evidence for the mechanisms by which cocaine elicits hemodynamic and pathologic responses in humans and animals. The emphasis will be on experimental data that provide the basis for our understanding of the mechanisms of cardiovascular toxicity associated with cocaine. More importantly, this review will identify several controversies regarding the causes of cocaine-induced cardiovascular toxicity that as yet are still debated. The evidence supporting these findings will be described. Finally, this review will outline the obvious deficits in our current concepts regarding the cardiovascular actions of cocaine in hope of encouraging additional studies on this grave problem in our society.

Embryonic "binge" cocaine exposure alters neural-immune and neural-endocrine interactions in young chickens: involvement of serotonin(2) receptors

As part of our characterization of the developmental consequences of prenatal cocaine exposure, cocaine was injected into eggs containing viable chicken embryos on embryonic day (E) 18 and the fever response to the endotoxin lipopolysaccharide (LPS) and a delayed-type hypersensitivity response to phytohemagglutinin (PHA) were assessed postnatally. E18 cocaine exposure did not affect basal body temperature. LPS induced a fever in the chicks at 4 h post-injection on post-hatch day (D) 4 and 2 h post-injection on D24. E18 cocaine exposure suppressed the peak LPS-induced fever by 50% at both ages. E18 cocaine exposure also suppressed the hypersensitivity reaction to an intradermal injection of PHA on D17, while having no effect on the response to a saline injection. To determine the importance of serotonin(2) (5-HT(2)) receptors in the developmental toxicity of cocaine, varying doses of the 5-HT(2) antagonist ritanserin were injected on E17 followed by cocaine on E18. Ritanserin, like cocaine, did not alter basal temperature, but it dose-relatedly attenuated or blocked cocaine's effect on LPS-induced fever on both D4 and D24. Ritanserin pretreatment was also able to block the blunted isolation stress response seen in D16 chicks following E18 cocaine exposure. Thus, late prenatal cocaine exposure significantly alters adaptive fever and hypersensitivity responses, and embryonic 5-HT(2) receptors played a mediating role in the fever effect.

Cocaine injection and coxsackievirus B3 infection increase heart disease during murine AIDS

Coxsackievirus initiates myocarditis especially in the immunologically deficient or immature. To test whether Coxsackievirus B3 (CVB3) induced pronounced cardiomyopathy during severe immune dysfunction of murine AIDS, female C57BL/6 mice were infected with LP-BM5 retrovirus and superinfected with CVB3. Some were also injected daily with cocaine hydrochloride in 0.9% saline solution (30 mg/kg) intraperitoneally, because cocaine also suppresses cellular immune response. Heart tissue was analyzed histopathologically. Mice experiencing concurrent retrovirus and Coxsackievirus infection had a high degree of cardiac lesions consistent with myopathy compared with findings in uninfected animals (p <.05). Cocaine injection during murine retrovirus infection greatly exacerbated the pathogenesis of Coxsackievirus infection. C57BL/6 mice, essentially resistant to Coxsackievirus-induced cardiomyopathy, became susceptible during the immune dysfunction in murine AIDS. This suggests that retrovirus infection causes conditions favoring Coxsackie-induced cardiac lesions. Interleukin (IL)-2 and IL-4 expression by splenocytes from the dually infected retrovirus and Coxsackievirus group showed no significant differences when the animals were also cocaine treated. However tumor necrosis factor TNF-alpha production was significantly decreased in dually infected retrovirus + Coxsackievirus mice treated with cocaine, compared with findings in various controls (p <.05).

Cocaine causes increased type I interferon secretion by both L929 cells and murine macrophages

Cocaine has been demonstrated to have a number of different effects on immune cell functions. We have reported alterations of cellular functions by macrophages (Mphi) exposed to cocaine in vitro, including the inhibition of mouse hepatitis virus replication. Here, we present evidence that cocaine stimulates the secretion of an antiviral product that is neutralized by anti-interferon (anti-IFN). A dose-dependent increase in the secretion of IFN by both Mphi and L929 cells incubated with cocaine, with a concomitant decrease in virus replication, is also reported. The increase in IFN secretion was most pronounced when cells were cultured in the presence of the IFN inducer poly(I.C). The effect of cocaine on IFN production was found to be primarily at the transcript level in both Mphi and L929 cells. These findings further support our previous research demonstrating an antiviral activity of cocaine in vitro. The relevance of this activity to viral infections in general remains to be determined.

Phantom Tooth Pain: A New Look at an Old Dilemma

The aim of this paper is to review the current knowledge of phantom tooth pain, a neuropathic facial pain disorder, thought to result from peripheral nerve injury. Phantom tooth pain is a deafferentation pain disorder of persistent toothache in teeth that have been denervated (usually by root canal treatment) or pain in the area formerly occupied by teeth prior to their extraction. The pain usually extends to the facial structures adjacent to tissues that have undergone deafferentation. The clinical characteristics, differential diagnosis, epidemiology, and treatment of phantom tooth pain are reviewed. Suggestions for further research include the need for controlled treatment trials and modification of current criteria.

CONCLUSIONS

Phantom tooth pain has much in common with other phantom pain disorders. In the absence of controlled clinical trials specifically directed to phantom tooth pain, treatment should be guided by standards used for other neuropathic pain disorders. Revised diagnostic criteria for phantom tooth pain are proposed.

Cytokine pattern secretion by murine spleen cells after inactivated Candida albicans immunization. Effect of cocaine and morphine treatment

In the present work we have analyzed: i) the effect of heat-inactivated Candida albicans immunization on the cytokine production by murine spleen cells; ii) the effect of a subchronic cocaine and morphine treatment on this production. The treatment with a single dose of inactivated Candida blastospores induced interleukin-2(IL-2), interferon-gamma (IFNgamma) and interleukin-4 (IL-4) production at 24 h after in vitro restimulation of splenocytes. In this model, the exposure to morphine (25 mg/kg, 5 days before, during and 5 days after inoculation with the yeast) significant decreased IL-2 and IL-4 levels, while secretion of IFN-gamma was unaltered. The same cocaine treatment (10 mg/kg) resulted in unchanged levels of the three cytokines tested. The results showed that non-viable Candida cells of this strain induce a predominant Th0 response. This immune effect is in part impaired only by a subchronic administration of morphine.

Effects of cocaine administration to influenza virus-immunized mice on cytokine profiles of individual splenic CD4+ and CD8+ T cells

We have analysed the effects of cocaine, administered to mice during the in vivo differentiation of effector T cells stimulated by antigen (influenza virus) recognition, on the frequency of IL-2-, IL-4- and interferon-gamma (IFN-gamma)-expressing CD4+ and CD8+ T cells. Each animal was injected intraperitoneally with 10 mg/kg of cocaine 6, 24, 48 and 72 h after immunization with A/PR8 influenza virus (PR8). This enabled the determination of the pharmacological effects of cocaine on T cells during the initial step of the immune response, which is characterized by the production of large amounts of immunoregulatory cytokines. The distribution of IL-2-, IL-4- and IFN-gamma-producing CD4+ and CD8+ T cells was assayed on unseparated PR8-immune spleen cells, obtained from mice treated with cocaine or vehicle, and restimulated in vitro with UV-inactivated PR8 virus. The frequency of T cells singly or co-expressing the above three cytokines was determined at single-cell level by simultaneous flow cytometric analysis of intracellular cytokines and surface antigen expression. In parallel, the levels of IL-2, IL-4 and IFN-gamma in the culture supernatants were quantified by ELISA. The results showed that cocaine, administered during the in vivo virus-induced differentiation of T cells, caused an increase of both the frequencies of CD8+ T cells singly and co-expressing IL-2 and IFN-gamma and the levels of these cytokines in virus-restimulated spleen cell culture supernatants, compared with those of untreated controls. In contrast, no effect was found on IL-4-positive CD8+ T cells and on IL-2-, IFN-gamma- and IL-4-positive CD4+ T cells. Our findings suggest that the immunomodulatory effects of cocaine may be due to the up-regulation of the production of IL-2 and IFN-gamma by CD8+ T cells with a type 0 cytokine profile.

Effect of short-term cocaine administration on the immune system of young and old C57BL/6 female mice

It has been shown that either cocaine or aging alone can alter the immune system. Our objective was to study if the immune system of aging mice was more susceptible to the effect of cocaine than the immune system of young mice. We used a short term (20 days) cocaine daily administration protocol. Cocaine only decreased the absolute number of Thy 1+, CD4+, CD8+, IL-2R+, Mac 1+ and B cells, in the spleen of old mice. Old untreated mice had a lower number of Thy 1+ cells in the thymus, and a higher number of cells expressing IL-2R. Cocaine decreased the number of Thy 1+ cells in the thymus of both age groups. Old mice showed a lower number of IgA+ plasma cells in the intestinal lamina propria (ILP) than young mice. Short term cocaine administration provoked a decrease in the number of CD4+ cells in young mice ILP and of CD8+ cells in old mice ILP. Our data suggest that cocaine can potentiate the effect of aging on the thymus and on the mucosal immune system. Taken together, our findings indicate that aging and cocaine can potentiate each other to impairing the host immune system.

Cocaine effects on immunocompetent cells: an observation of in vitro cocaine exposure

This study investigated in vitro effects of cocaine on the function of T and B lymphocytes, natural killer cells and macrophages in a mouse model. In mature C57BL/6J mice (60-90 day-old), splenocytes were cultured with cocaine at different concentrations ranging from 4 to 64 microg/ml for 24 h. The exposure to cocaine in vitro was found to affect (1) T cell function, with reduced responses to stimulation of Con-A, PHA and Interleukin 2, and decreased production of gamma-IFN; (2) B cell function, with reduced response to LPS; (3) natural killer cell function, with attenuated killing capacity; (4) monocyte-macrophage function, with decreased ability to inhibit the growth of tumor cells. The results of the study indicated a direct cocaine effect on four major immune competent cells, and the generally suppressive effects of in vitro cocaine exposure may be related to its in vivo action on the immune system.

Differential effects of acute morphine administrations on polymorphonuclear cell metabolism in various mouse strains

This paper shows that an acute morphine treatment dose-dependently alters the energetic and oxidative metabolism of polymorphonuclear leukocytes obtained from BALB/c and DBA/2 mice, while phagocytic cells from C57BL/6 were not affected. In sensitive mouse strains, i.e. BALB/c and DBA/2, morphine decreased both ATP concentration and energy charge potential. At the same time, ATP catabolic products, i.e. nucleosides (inosine+adenosine) and oxypurines (hypoxanthine+xanthine+uric acid), significantly increased, indicating an imbalance between energy production and consumption. Morphine treatment also induced malondialdehyde and superoxide anions production in leukocyte cells from sensitive mice. The opiate antagonist naloxone blocked morphine-induced modifications by the lower morphine dose. The same parameters in cells from C57BL/6 mice were not affected. These findings confirm that: i) the phagocytic cells are an important target for the in vivo effects of morphine, and ii) the genotype-dependent variation influences the immunological responsiveness to opiates.

Cocaine induced T cell proliferation in the rat: role of amygdala dopamine D1 receptors

The immunomodulatory effects of local administration of cocaine into the amygdala were studied in the rat. Intra-amygdala infusion of cocaine significantly and dose-dependently increased the proliferative response of splenocytes to concanavalin A (Con A). A similar effect on the immune response was also observed in rats, microinfused into the central amygdala with the selective D1 receptor agonist SKF 38393. The increase of the proliferative response of splenocytes to Con A was inhibited by coinfusion within the central amygdala of the dopamine D1 receptor antagonist SCH 23390, together with cocaine, but not by coinfusion of the dopamine D2 receptor antagonist eticlopride. These results suggest that cocaine may produce at least some of its effects on the immune system through the activation of brain dopamine neurotransmission and that the central amygdala may represent a critical structure mediating cocaine-induced T cell proliferation.

Open-field and LPS-induced sickness behavior in young chickens: effects of embryonic cocaine and/or ritanserin

Exposure to drugs of abuse during embryogenesis may adversely affect nervous, immune, and endocrine systems development. We compared exposure on embryonic day 18 (E18) by single or multiple cocaine (COC) injections (56.25 mg/kg total dose for both) or saline on hatching and activity measures. In saline-exposed controls, repeated testing, age, and gender affected activity levels. A single or multiple COC injections increased the median latency to explore and multiple COC injections decreased the median number of lines crossed by female chicks in the open field. We also determined if pretreatment with the serotonin2 (5-HT2) receptor antagonist ritanserin could attenuate COC's effects on open-field behavior as well as behaviors sensitive to immune system stimulation (lipopolysaccharide (LPS)-induced sickness behavior). Eggs containing embryos were pretreated on E17 with 0.4 mg ritanserin/kg or its vehicle followed by multiple COC injections or saline on E18. E18 COC treatment decreased the median number of lines crossed and distress vocalizations in females. Ritanserin pretreatment mitigated the COC induced effects. E18 COC exposure also suppressed LPS-induced sickness behaviors in both males and females, increasing food consumption and the time spent awake and active, as well as decreasing the time spent sleeping. Ritanserin alone had no effect on the food consumed or time spent active, nor did this dose affect COC-induced alterations in sickness behavior. Ritanserin alone decreased time spent sleeping and also failed to affect the COC-induced suppression. Thus, embryonic COC exposure can suppress open field and LPS-induced sickness behavior in the young chick, and ritanserin pretreatment can block the former, but not the latter effects at the dose chosen for these experiments.

Peripheral human T lymphocyte maintenance of immune functional capacity and phenotypic characteristics following in vivo cocaine exposure

The effects of cocaine exposure upon the host's immune response is equivocal since a variety of studies have generated conflicting conclusions, often as the result of differences between in vitro and/or animal models and the actual conditions experienced in humans who are acutely abusing this drug. To further address this issue, we have studied a group of patients who were positive for cocaine or cocaine metabolites and we evaluated a variety of functional parameters of T-lymphocytes and other peripheral lymphoid cell populations, as well as immunophenotypic characteristics of these cells. When compared to normal controls and patients who were negative for cocaine, we found that the cocaine-positive patients had T-cell functional assays which were essentially normal, with the exception of a slight depression in PHA stimulation. Likewise, the immunophenotype of the peripheral blood lymphocytic populations showed normal percentages and numbers of their T cell subsets (CD4, CD8), NK cells, and B cells. Multicolor flow cytometry analysis revealed no difference in T cell subpopulations positive for the "memory" marker, CD62L. No correlation could be established between levels of cocaine or cocaine metabolites and any phenotypic, demographic, or functional parameter. In summary, these results demonstrate that individuals acutely exposed to cocaine do not show markedly altered T cell function or fluctuations in phenotypically identified cell populations. These studies imply that acute cocaine exposure does not predispose individuals to grossly apparent immunosuppression. However, the possibility that subtle, transient, or more specific changes in the immune system may be incurred by use of cocaine, particularly with chronic exposure, remains to be determined.

The thymolytic effect of cocaine and monoaminergic drugs in the mouse

Cocaine abuse is known to be associated with suppression of the immune system. In this experiment, animals treated with cocaine (CC) in their drinking water (200 mg/L) for 10 days resulted in a significant decrease in thymus weight in HSD-NDA male Swiss mice. A subsequent in-vitro experiment was designed to investigate the direct effect of cocaine and other dopaminergic agents on thymocyte proliferation. Thymus glands were aseptically removed from mice and thymocytes were isolated and then incubated in microtiter plates with various concentrations (10[-8]-10[-4] M) of CC, apomorphine (AM), haloperidol (HP), dopamine (DA) and epinephrine (EN) for 18 hrs. The results revealed that cocaine inhibits [3H]-thymidine uptake into DNA in a dose-dependent manner. Apomorphine, haloperidol and dopamine also exhibited a similar dose dependent inhibition of thymocyte proliferation. The IC25s for DNA synthesis inhibition were 8.2 x 10(-6) M, 4.3 x 10(-7) M, 2.5 x 10(-7) M, and 1.1 x 10(-7) M for CC, HP, DA and AM, respectively. EN was found not to have any significant effect on DNA synthesis. The results suggest that thymus gland atrophy, associated with use of CC may be related to the inhibition of thymocyte proliferation.

Suppression of splenic T lymphocyte proliferation by acute cocaine administration

We have recently demonstrated that cocaine administration has a limited effect on mitogen-stimulated T lymphocyte proliferation. The present study investigated the effect of cocaine on splenic T cell response to alloantigens. Rats received intraperitoneal injections of cocaine HCI, and splenocytes were isolated either thirty minutes or three hours post-administration. In the thirty minute exposure group, cocaine at 10.0 and 25.0 mg/Kg/B.Wt. suppressed (p<0.05) T cell proliferation in mixed lymphocyte cultures. Compared to control data, proliferation was decreased by 46.6% and 56.4%, respectively. However, this effect was not as pronounced in cells isolated three hours post-administration, indicating a transient inhibition of T cell function by cocaine. The decrease in splenic T cell proliferation in response to alloantigens in the thirty minute exposure group did not reflect alterations in calcium influx or IL-2 production. Although this study did not ascertain the exact mechanism of inhibition, these results demonstrate that short-term cocaine exposure can alter T cell reactivity to alloantigens, suggesting a reduction in the functional status of these cells.

The interactive effects of cocaine/gender on immune function in mice. An observation of in vivo acute cocaine exposure

The present experiments used a mouse model including both sexes to study the impact of acute cocaine exposure on the function of four major immunocompetent cell types (T, B cells, NK, and macrophages). Cocaine hydrochloride, 5 mg or 40 mg/kg, was administrated by i.p. injection to C57BL/6 mice. Thymocytes and splenocytes were obtained 24 h after injection. Acute in vivo cocaine exposure inhibited the proliferation of T lymphocytes in response to Con-A in both thymocytes and splenocytes. However, the attenuated IL-2 production was only seen in thymocytes. These effects on T cells were greater in male mice than in female mice. The function of macrophages was also impaired by acute cocaine exposure; however, the impact was greater in female than in male mice. In conclusion, the effects of acute cocaine exposure altered the functions of immunocompetent cells and the effects varied with gender.

Developmental immunotoxicity of cocaine and ethanol in postnatal Lewis rats

The immunomodulatory effect of cocaine (COC), ethanol (EtOH) and their combination was investigated in the developing immune system of postnatal Lewis rats. To simulate the route of exposure during lactation, newborn rats were orally treated with either saline, 20 mg COC/kg, and 0.6 g EtOH/kg or the coadministration of COC and EtOH from day 1 to 21 of life. Rat pups were sacrificed thirty minutes following the last treatment. Total lymphocytes and spleen/body weight ratios were decreased in animals exposed to COC. These immunotoxic effects were not enhanced by the coadministration of EtOH. However, pups exposed to both drugs had significantly decreased levels of serum immunoglobulin M (IgM) when compared to saline-treated rats. Plasma and tissue distribution studies revealed that the combination treatment group had a higher COC content in the brain and spleen as well as an increase in the metabolites benzoylecognine (BE) and norcocaine (NC) in the spleen. Ethylcocaine (EC) formation was not demonstrated in this model.

Immunologic effects of cocaine in prenatally exposed rats and mice

The immunotoxicity of prenatal cocaine exposure was investigated using Sprague-Dawley rats and C57B1/6 mice. Pregnant animals were injected twice a day with cocaine or saline from gestation day 5 until the day before parturition. The immune system of the rat offspring was evaluated at 8 weeks of age by measuring the antibody response to SRBC (plaque assay and serum IgM), delayed-type hypersensitivity response to KLH, and lymphocyte subpopulations in the spleen and thymus using flow cytometry. The immune system of the mice offspring was evaluated at 4 weeks of age by measuring spleen cell proliferation in response to KLH, LPS, and alphaCD3 and IgG production to KLH. From the differences observed between cocaine exposed animals and controls, we conclude that prenatal cocaine exposure does not cause lasting detrimental effects on the immune system, but instead, may enhance B-cell responsiveness.

Effect of sub-chronic cocaine and lidocaine exposure on the lymphoid tissues in neonatal rats

Illicit cocaine varies in purity and is often adulterated with local anesthetics such as lidocaine. Chronic cocaine exposure is associated with immunological modulation in humans and animal models. The effect of sub-chronic oral exposure to cocaine (COC) and lidocaine (LIDO) alone and in combination on the lymphoid organs was assessed in neonatal rats. Lewis rat pups were orally administered saline (SAL), COC, LIDO or both drugs in combination, 20 mg/kg each, from birth to day 21. Statistically significant (P < 0.05) decreases in lymphocyte and total leukocyte levels as well as decreases in spleen weight were observed in pups treated with COC alone. LIDO alone did not affect these parameters in comparison to SAL treated controls. Rats receiving COC and LIDO did not display a significant reduction in spleen weight or in the blood cell populations studied. However, rats treated with COC and LIDO in combination had significantly decreased serum immunoglobulin M (IgM) concentration. Quantitative plasma and tissue analyses ascertained the concentrations and tissue disposition of each drug following oral administration. The results suggest that the effect of COC on the lymphoid tissues and white blood cell parameters is modified in the presence of LIDO in the developing rat.

Cocaine/sex type effects on T lymphocytes: a preliminary report

The influence of gender on the effects of cocaine (5 or 40 mg/kg) on immune function of sexually immature (35-day-old) C57BL/6J mice was assessed. The proliferation of T cells in thymus and spleen stimulated with phytohemagglutinin (PHA) and concanavalin-A(Con-A) was determined by 3H thymidine incorporation 24 hours after cocaine injections. The drug produced a dose-dependent reduction (25-51%) of Con-A and PHA-stimulated T cell proliferation in thymus from both male and female mice. Additionally, the impairment occurred at a lower cocaine dose for female than for male mice when the T cells were challenged with PHA. Under the experimental conditions, cocaine did not alter weights or cell numbers of thymus and spleen or T cell proliferation in spleen.

Role of metabolism in ethyl carbamate-induced suppression of antibody response to sheep erythrocytes in female Balb/C mice

A possible role of metabolism by cytochrome P450 (P450) in ethyl carbamate-induced suppression of the antibody response to a T-cell-dependent antigen, sheep erythrocytes (SRBCs), was investigated in female Balb/C mice. When mice were treated with ethyl carbamate intraperitoneally for 14 consecutive days at 25, 50, 100, 200 and 400 mg/kg, the antibody response was significantly suppressed from 200 mg/kg. These doses also caused a decrease in thymus weight. An acute dosing of ethyl carbamate at 1 g/kg also caused not only a significant suppression of the antibody response, but also a decrease in thymus weight. The antibody response was most likely to be the IgM antibody response, which was demonstrated in a haemagglutination study. When mice were pretreated with phenobarbital (80 mg/kg) for 3 days to induce P450 enzymes, followed by administration of ethyl carbamate intraperitoneally for 7 consecutive days, the antibody response was more suppressed than in saline-pretreated controls. Moreover, a study using aminoacetonitrile, a P450 inhibitor, showed that the antibody response suppressed by ethyl carbamate was completely recovered by the inhibitor. The present results suggest that metabolism of ethyl carbamate by P450 may be the critical pathway to produce metabolites capable of suppressing the antibody response.

Role of metabolism in cocaine-induced immunosuppression in splenocyte cultures from B6C3F1 female mice

Cocaine has been reported to directly suppress the in vitro immune responses at very high concentrations. In the present study, the possible role of metabolism in cocaine-induced immunosuppression was investigated in splenocyte cultures isolated from B6C3F1 female mice. Since cocaine can be metabolized by both esterase and P-450 monooxygenase, we studied the direct effects of cocaine, benzoylecgonine and norcocaine on the in vitro T-dependent antibody response to SRBC. Direct exposure to cocaine only produced a modest (30%) but nonsignificant suppression of the antibody response, while benzoylecgonine, a primary product of metabolism by the esterase pathway, was devoid of activity. In contrast, direct exposure to norcocaine, the initial product of N-demethylation by the P-450 pathway, produced significant suppression at concentrations greater than or equal to 10 microM. Similar results were observed in studies measuring LPS and Con A mitogenicity. Furthermore, a significant suppression was observed when splenocytes were preincubated for 1 h with 1 mM cocaine in the presence of liver S-9 fractions isolated from phenobarbital-induced mice. Meanwhile, no suppression was obtained when splenocytes were preincubated in the presence of untreated S-9 fractions. To characterize the mechanism of our results, the capacity of both untreated and phenobarbital-induced microsomes to produce formaldehyde from cocaine was compared. The N-demethylation of cocaine was NADPH-dependent and phenobarbital-induced microsomes produced approx. 6-times higher amounts of formaldehyde, indicating a greater portion of cocaine could be metabolized through the P-450 pathway to its toxic metabolites. Finally, because benzoylecgonine shares with cocaine the presence of a methyl group on the tropane nitrogen, we also compared the ability of N-demethylation from cocaine and benzoylecgonine in mouse liver microsomes. Our results indicated that benzoylecgonine could not be demethylated as determined by a failure to generate any formaldehyde. These results offer further support that the N-demethylation pathway is a critical step to cause its immunotoxicity.

Effect of cocaine administration on concanavalin A-stimulated T-lymphocyte proliferation in rats

There is a high prevalence of cocaine abuse among Americans. There is an increasing concern over the rise of infectious diseases among individuals in this drug abuse population. This concern may be due, at least in part, to a direct effect of cocaine on the immune system. The present study investigated the effects of cocaine administration on optimal mitogen-induced proliferation in rats. Following cocaine administration, splenic lymphocytes were isolated and T-lymphocytes incubated with concanavalin A. When T-lymphocytes were isolated 30 minutes following cocaine administration, a significant enhancement of optimal mitogen-stimulated proliferation was observed at 0.1 mg/Kg cocaine. Enhancement of proliferation was seen 20 hours following cocaine administration at 0.1, 1.0 and 10 mg/Kg. However, these results were not statistically significant. Cocaine administered once daily for seven days had no effect on mitogen-induced proliferation. These results suggest that cocaine administration has a limited effect on optimal mitogen-stimulated proliferation.

Cocaine blunts human CD4+ cell activation

Cocaine is reported to be immunotoxic. The biochemical mechanisms responsible for the immunopharmacological outcomes of cocaine in vivo and in vitro remain, however, to be fully elucidated. Our experimental data confirm that exposure of normal human T cells to micromolar concentrations of cocaine modulates T-cell responses to stimulation by a variety of stimuli, and indicate that cocaine impairs early activation events during CD4+ but not CD4- T-cell stimulation. Pre-incubation of enriched CD4+ T-cell subpopulations that express the homing receptor CD62L with nanomolar concentrations of the endogenous opioid peptide beta-endorphin leads to a more severe impairment of activation than that noted following pre-incubation with micromolar concentrations of cocaine alone. These findings begin to elucidate the molecular and cellular mechanisms of the immunopathology of cocaine. Our data support the proposition that cocaine abuse may place cocaine-abuser HIV-seropositive individuals at increased risk of opportunistic infections.

The effect of alcohol consumption on nutritional status during murine AIDS

As alcohol (ETOH) abusers and AIDS patients have nutritional disorders, the influence of chronic ETOH consumption (5% v/v for 10 weeks) on levels of immunomodulatory nutrients (vitamins A and E, Zn, and Cu) in the serum, liver, small intestine, spleen, and thymus was determined during murine AIDS. The hepatic levels of vitamins A and E and Zn in both normal and LP-BM5 retrovirus-infected female C56BL/6 mice fed ETOH were significantly reduced compared to controls, whereas the level of Cu in the liver was not affected. Intestinal levels of vitamin A and Cu were not affected by ETOH, whereas vitamin E and Zn were significantly reduced in both normal mice and those with AIDS fed ETOH. The splenic levels of vitamin A and Zn in the normal mice were significantly reduced by ETOH compared to controls, but vitamin E and Cu were not. All splenic levels of nutrients measured were reduced in ETOH-fed mice with AIDS. The levels of vitamins A and E, Zn, and Cu in the thymus in murine AIDS were also significantly affected by ETOH consumption. The serum levels of vitamins A and E in both normal mice and murine AIDS were significantly decreased by dietary ETOH. These data produced evidence that chronic ETOH can directly aggravate undernutrition initiated by retrovirus infection. Such ETOH-induced malnutrition in AIDS may be a cofactor, accelerating development of AIDS via immunosuppression secondary to nutritional deficiencies.

Dietary vitamin E modulation of cytokine production by splenocytes and thymocytes from alcohol-fed mice

As vitamin E enhances immune responses, it may reduce dietary ethanol (EtOH)-induced immune suppression, thereby favorably affecting host disease resistance. The effects of dietary vitamin E at higher level in alcohol-fed female C57BL/6 mice was determined via in vitro cytokine production by splenocytes and thymocytes, and some other immune functions. A 15-fold increase of vitamin E (160 IU/liter) in a liquid diet (National Council Research), with or without EtOH (4.5%, v/v), was fed to mice for 10 weeks. Vitamin E supplementation restored production of interleukin-2, -5, -6, -10, and interferon-gamma by concanavalin A (Con A)-stimulated splenocytes and interleukin-6 and tumor necrosis factor-alpha by lipopolysaccharide-stimulated splenocytes, which were suppressed by dietary EtOH. However, it had no effect on interleukin-4 secretion, which was also reduced by splenocytes from EtOH-fed mice. Vitamin E supplementation also restored EtOH-suppressed, mitogen-induced splenocyte proliferation, but not thymocyte proliferation, although it slightly increased production of immunoglobulin A and G by lipopolysaccharide-stimulated splenocytes, which were suppressed by dietary EtOH. Dietary vitamin E, furthermore, significantly increased interleukin-2 and -6 secretion by Con A-stimulated thymocytes, which were suppressed by dietary EtOH, although it had no effect on interleukin-4 and interferon-gamma production by Con A-stimulated thymocytes from EtOH-fed mice. These data suggest that dietary vitamin E supplementation can modulate dysregulation of cytokines initiated by dietary EtOH and restore immune dysfunctions induced by EtOH ingestion.

Inhibition of cytokine release by cocaine

The influence of cocaine on cytokine release by mouse peritoneal macrophages has been investigated in vitro. LPS-stimulated TNF and IL-1 secretion were suppressed by cocaine in higher dosages. This suppression was shown to be dose-related. The synthesis of cAMP, however, was stimulated by cocaine. Though cAMP is generally considered a mediator for cytokine release, further studies are required to demonstrate whether cocaine directly affects cytokine release by macrophages or indirectly influences cytokine release through stimulating cAMP synthesis.

Ethanol, immune responses, and murine AIDS: the role of vitamin E as an immunostimulant and antioxidant

Excessive alcohol consumption is a major health problem in the United States. Prolonged consumption of alcohol results in alterations of immune responses, ultimately manifested by increasing susceptibility to infectious agents. Such changes can be due to the direct effects of alcohol or its metabolites on immune cells, as well as to nutritional deficiency, oxidative stress, and neutrophil dysfunctions. This ETOH-induced immunosuppression could be a potential cofactor in the progression to AIDS. As vitamin E supplementation has been associated with enhancement of immune response and improvement of host defense, it may provide a useful therapeutic approach for treatment of alcoholics to improve host defense. This article is a review of alcohol-related immunosuppression as a possible cofactor in the development of AIDS, and vitamin E-related immunoenhancing roles in animals and humans, showing why vitamin E supplementation could be used as a useful adjunct agent in alcoholics' treatment. Since there is little information available regarding nutritional therapy with alcohol users, our purpose is to provide evidence from animal models of the potential therapeutic role of vitamin E supplementation in the treatment of alcoholics.

In vivo and in vitro cocaine modulation on production of cytokines in C57BL/6 mice

In the present study we used both in vivo and in vitro murine models to investigate the effects of cocaine on the release of cytokines (IL-1 alpha, IL-6, and TNF-alpha by peritoneal macrophages and splenocytes, IL-2, IL-4, IL-5, IL-10, and IFN-gamma produced by splenocytes. In vitro cocaine (0.1, 1, 10, 100 micrograms/ml) exposure inhibited all cytokines produced by ConA-stimulated spleen cells and LPS-stimulated macrophages in a concentration dependent manner. Different effects of cocaine administration on cytokine production were observed when female C57BL/6 mice were injected intraperitoneally with cocaine (40 mg/kg body weight for six weeks). Secretion of IL-2 by splenocytes was significantly enhanced by cocaine administration, whereas IFN-gamma was not affected. Secretion of IL-4 and IL-10 by splenocytes was significantly inhibited by cocaine administration, while secretion of IL-5 by splenocytes was significantly enhanced. Secretion of IL-6 and TNF-alpha by splenocytes was significantly enhanced by cocaine administration. Secretion of IL-6 by peritoneal macrophages was also significantly enhanced by the cocaine, while production of IL-1 alpha was not affected. However, release of TNF-alpha by peritoneal macrophages was significantly reduced by the cocaine administration. Therefore use of cocaine may alter the balance of cytokine production, and thereby adversely affects immune response and host defense.

Effect of cocaine and murine AIDS on lamina propria T and B cells in normal mice

We developed an experimental model to study the effect of daily cocaine administration on the mucosal immune system during murine acquired immune deficiency syndrome (MAIDS). Mice were infected with LP-BM5 murine leukemia virus, a retrovirus which causes immunosuppression with development of functional murine AIDS. Mice were given cocaine by daily intraperitoneal injection for 11 weeks. Our objective was to investigate if cocaine treatment could alter the mucosal immune system at the level of the intestinal lamina propria (ILP) and if it could further modify the already altered mucosal immunity when it was administered to MAIDS-mice. Daily cocaine administration induced a significant decrease in the number of IgA+ cells with a concomitant increase in the number of CD8+ cells per villi in the ILP. Murine retrovirus infection alone decreased the number of IgA+ and CD4+ cells in the ILP, and this decreased was even more marked when MAIDS mice also received cocaine. These data indicate that cocaine administration could potentiate the dramatic effect that MAIDS infection has in the mucosal-associated lymphoid tissues.

Differential effects of short-term or prolonged cocaine exposure on peripheral blood cells in mice

The effects of cocaine on the number of murine peripheral blood cells and on phenotypic expression of lymphocyte subsets were examined using different regimens of drug exposure. Cocaine administered to mice for 7 consecutive days at 1 and 10 mg/kg/day reduced the absolute number of circulating white blood cells and the relative number of cells stained as lymphocytes, polymorphonuclear cells and monocytes. Cocaine did not modify the relative proportion between lymphocytes, polymorphonuclear cells and monocytes. Parallely, there were no changes in the percentage of circulating CD4+ and CD8+ lymphocytes, while the number of natural killer cells increased. In sharp contrast, we didn't observe any significant change in peripheral blood cells after 30 days of consecutive drug administrations.

Effect of synthetic thymic hormones on the cocaine-induced inhibition of the primary immune response in mice

The effects of thymosin alpha 1 (T alpha 1) and thymopentin (TP5) on the cocaine-induced impairment of the primary antibody response to sheep red blood cells (SRBC) was studied. The administration of cocaine from day -4 to the day of immunization (day 0) induced a significant impairment of the response to the T-dependent antigen SRBC, as evaluated on day 5 post-immunization by the Splenocyte-Induced SRBC Hemolysis (SIH) assay. The analysis of the responses to immunogen elicited from each single mouse indicated that, under the experimental conditions used, cocaine acted by exerting more an "all or nothing" effect rather than by modulating the strength of the immune response. Both T alpha 1 and TP5, injected into mice during cocaine administration and for 4 days after, induced a significant recovery of the response to SRBC. Our experiments did not show any great differences in the overall efficacy of the two drugs, although they showed quite a different dose-response effect. The results of the present investigation demonstrated the capability of TP5 and T alpha 1 to reverse the cocaine-induced impairment of the response to SRBC and suggested that the effect of the two peptides may be related to their immunomodulating activities on T-cell functions.

Cocaine reduces macrophage killing by inhibiting reactive nitrogen intermediates

The present study describes the inhibition of macrophage-mediated cytotoxicity (MMC) by cocaine and suggests a possible mechanism. Mice (C57BL/6) were injected i.p. with cocaine. At various intervals after exposure to cocaine, peritoneal macrophages (M phi) were removed, cultured in the presence of interferon gamma and LPS, then incubated with 51Cr labeled target cells. A single injection of > or = 10 mg/kg cocaine was sufficient to inhibit cytotoxicity to P815 cells. This inhibition was evident 3 h after exposure to cocaine and could still be demonstrated 24 h later. Since reactive nitrogen intermediates (RNI) have been reported to be one of the major mechanisms by which M phi kill, the amounts of NO2- produced by M phi from cocaine-injected animals were compared with that produced by equivalent controls. Cocaine reduced the level of NO2- in a dose-dependent manner which correlated with MMC. There was a significant reduction in NO2- produced by activated M phi, 3 h after i.p. injection of cocaine but not at 24 h, using > or = 5 mg/kg. At 12 h there were differences between M phi from control animals and animals receiving > or = 10 mg/kg cocaine. By 24 h there were no differences between control and cocaine-injected animals even at the highest dose employed (25 mg/kg). These results suggest that cocaine reduces the killing ability of murine M phi through a temporary reduction of RNI.

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.

Alterations of corticotropin-releasing factor-like immunoreactivity in different brain regions after acute cocaine administration in rats

Corticotropin-releasing factor (CRF) may mediate some of the neuroendocrine and behavioral responses to cocaine. In this study, the distribution of CRF-like immunoreactivity (CRF-LI) was determined in the hypothalamus and in several extrahypothalamic brain regions after acute cocaine administration in handled rats. CRF-LI decreased dose-dependently with cocaine administration in the hypothalamus and in the basal-forebrain structures. A small dose of cocaine (7.5 mg/kg) decreased CRF-LI in the hippocampus and in the frontal cortex. A significant, selective, dose-dependent increase in CRF-LI was found in the amygdala after cocaine injection. None of the investigated doses of cocaine altered CRF-LI in the striatum. These results suggest that acute cocaine administration alters brain CRF systems to contribute behavioral and neuroendocrine responses to cocaine.

Entangled epidemics: cocaine use and HIV disease

Over the past decade, two epidemics have had a severe impact on public health in this country. These health problems involve cocaine abuse and AIDS (or HIV disease). The processes of these two conditions are clearly not independent of each other and may be quite complex. Understanding of this relationship has been hampered by a myriad of social, biological and behavioral variables that are entangled with the basic cocaine-HIV association. This article presents a paradigm for discussion of the interaction between cocaine exposure and HIV disease based on three mechanisms: the relationship between cocaine exposure and increased opportunity for HIV exposure, the direct role that cocaine plays in altering susceptibility to HIV infection, and the influence that cocaine use has on the progression of HIV disease. The goal of this structured approach is to enhance conceptual understanding of the cocaine-HIV relationship while recognizing the complexity of the issue and the limitations of current research efforts. This model will serve as a framework for the discussion of implications for future research, clinical practice, and public policy.

The effects of methadone on immune function among injecting drug users: a review

Methadone maintenance therapy is advocated as a major preventive strategy for the spread of the human immunodeficiency virus (HIV) and other blood-borne infectious agents among injecting drug users (IDUs) because of its effects in decreasing the frequency of injecting and presumably sharing of equipment. As an opioid agonist, methadone may share the direct and indirect immunoregulatory effects of other opioids, and thus affect susceptibility to, and the natural history of, HIV infection. Available evidence pertaining to methadone and immune function is reviewed. The long-term immunosuppression observed in heroin injectors on present (incomplete) evidence appears to be caused by factors associated with a drug-using lifestyle rather than by a direct action of heroin. Although data are conflicting, it is most likely that methadone does not significantly impair immune function and is safe for HIV-infected IDUs, possibly even allowing some improvement of immune function to occur. The increasing reliance placed on methadone maintenance to control the epidemic of HIV infection in IDUs requires that remaining uncertainties regarding methadone and immune function are clarified urgently.

Is phantom tooth pain a deafferentation (neuropathic) syndrome? Part I: Evidence derived from pathophysiology and treatment

Phantom tooth pain is a syndrome of persistent pain or paresthesia in teeth and other oral tissues that may follow dental or surgical procedures such as pulp extirpation, apicoectomy, tooth extractions, or exenteration of the contents of the maxillary antrum. It can also occur when nerves are injured after trauma to the face or even after routine inferior alveolar nerve blocks if the needle pierces the nerve sheath. In the case of tooth extraction, the pain is found in the edentate area. After periodontal surgery, pain or paresthesia is located in the gingiva. The incidence of phantom tooth pain after extirpation may be as high as 3% of cases. Clinically, phantom tooth pain is similar in many essential characteristics to deafferentation pain syndromes also known as phantom pain syndromes. A limitation to this taxonomy is the lack of definitive information with respect to the pathophysiology of deafferentation pain in the trigeminal nerve. This article amplifies previous clinical descriptions of phantom tooth pain. Current concepts in the pathophysiology of neuropathic pain are reviewed as they pertain to phantom tooth pain. Treatments are described that use three routes of drug administration: oral, nerve blocks by injections, and intranasal applications. Reasons are discussed for the high rates of morbidity after dental and neurosurgery in attempts to treat phantom tooth pain.

Effects of cocaine on the respiratory burst of murine macrophages

Cocaine is a central nervous stimulant with a major potential for abuse. It is used clinically as a local anesthetic and vasoconstrictor. The effects of cocaine on the immune system have not been studied in depth. In this study, we have investigated the effects of cocaine on the respiratory burst (RB) of murine macrophages (M phi). The RB was measured by determining the increase in chemiluminescence. Both peritoneal and alveolar M phi were isolated from cocaine-exposed mice and saline-exposed controls. Cocaine was administered by the intraperitoneal, intravenous, and intramuscular route. Both peritoneal and alveolar M phi from cocaine-exposed mice showed an increase in chemiluminescence when compared with M phi from matched controls. This effect was seen as early as one hour after cocaine exposure and lasted for up to 48 hours. Intraperitoneal injection of cocaine metabolites did not affect the RB. Macrophages exposed to cocaine in vitro failed to respond by an increase in RB. These findings indicate that cocaine induces the production of reactive oxygen intermediates (ROI) and suggests possible changes in M phi functions.

Cocaine facilitation of cryptosporidiosis by murine AIDS in male and female C57/BL/6 mice

As cocaine may affect progression of the Human Immunodeficiency Virus (HIV) infection to Acquired Immune Deficiency Syndrome (AIDS), we used a murine model of AIDS (MAIDS) induced by LP-BM5 murine leukemia virus to examine cocaine's possible role as a cofactor for secondary parasitic infections. Dissimilarities between the sexes were observed both in the absence and presence of the cocaine. The retrovirus-infected female mice had a much higher rate of Cryptosporidiosis than the retrovirus-infected male mice. Female, but not male, retrovirus-infected mice showed approximately 20-fold more Cryptosporidium per villus section than controls. Compared to respective gender controls, male and female animals infected with the retrovirus infection manifested a heightened Cryptosporidium oocysts count regardless of cocaine treatment. Overall, female groups incurred a higher incidence of infection compared to respective male groups. To determine the role of cocaine, groups of male and female C57BL-6 mice of similar age were treated with cocaine for 4 weeks followed by termination. Cocaine synergized with retrovirus infection in female mice to cause a 30-fold increase in the number of oocyst present. The spleen size and weight of female mice was significantly greater than uninfected controls or male mice. However, due to the very slow progression to murine AIDS in the males, parasite resistance was retained, including in cocaine treated C57BL-6 mice. Thymus cell number in the retrovirus-infected female mice decreased significantly in comparison to uninfected female controls. Continued resistance to the parasite in male mice and its loss in female mice was due to the rate of immunosuppression and thus development of retrovirus-induced murine AIDS.