Alcohol and drug use disorders, HIV status and drug resistance in a sample of Russian TB patients

SETTING

Alcohol use, tuberculosis (TB) drug resistance and human immunodeficiency virus (HIV) risk behavior are of increasing concern in Russian TB patients.

DESIGN

A prevalence study of alcohol use and HIV risk behavior was conducted in a sample of 200 adult men and women admitted to TB hospitals in St Petersburg and Ivanovo, Russia.

RESULTS

Of the subjects, 72% were men. The mean age was 41. Active TB was diagnosed using a combination of chest X-ray, sputum smears and sputum cultures. Sixty-two per cent met DSM-IV criteria for current alcohol abuse or dependence. Drug use was uncommon, with only two patients reporting recent intravenous heroin use. There was one case of HIV infection. The mean total risk assessment battery score was 3.4. Depression was present in 60% of the sample, with 17% severely depressed. Alcohol abuse/dependence was associated with an eight-fold increase in drug resistance (OR 8.58; 95% CI 2.09-35.32). Patients with relapsing or chronic TB were more likely to meet the criteria for alcohol abuse/dependence (OR 2.56; 95% CI 1.0-6.54).

CONCLUSION

Alcohol use disorders are common in patients being treated for active TB, and are associated with significant morbidity. Additional surveys are needed to examine the relationship between alcohol use disorders and anti-tuberculosis drug resistance.

The onset of HIV infection in the Leningrad region of Russia: a focus on drug and alcohol dependence

OBJECTIVES

Within 5 years, 5 million Russians may be infected with HIV. Currently, injection drug use is the major risk factor for HIV. As Russia's alcohol consumption per capita is among the highest in the world, alcohol-associated behaviours may be an important contributor to the HIV epidemic. Our objective was to examine the prevalence of HIV infection among drug- and alcohol-dependent patients in a regional narcology hospital and in the general population in Leningrad.

METHODS

All patients in the Narcology Hospital, Leningrad Regional Center of Addictions (LRCA), were tested for HIV antibody between 1997 and 2001. We reviewed these clinical records (i.e. serostatus, gender, age, and addiction) and data from the HIV/AIDS Center in the Leningrad Region (1997-2001).

RESULTS

From 1997 to 2001, HIV prevalence at the LRCA increased from 0 to 12.7% overall, 33.4% among drug-dependent patients and 1.2% among alcohol-dependent patients. During the same 5-year period (1997-2001), 2826 persons were registered at the HIV/AIDS Center: 6, 6, 51, 780, and 1983 persons in 1997, 1998, 1999, 2000 and 2001, respectively.

CONCLUSIONS

HIV infection is exploding in the Leningrad Region, currently in injection drug users (IDUs) but potentially more broadly. The known high per capita alcohol intake in Russia heightens concern regarding the sexual transmission of HIV. Interventions to prevent such a development should include use, and assessment of the effectiveness, of known HIV prevention measures for at-risk and infected individuals.

Effects of abused drugs on thresholds and breaking points of intracranial self-stimulation in rats

The present study aimed to compare the effects of various abused drugs on threshold current intensities and the breaking points of intracranial self-stimulation. Effects of morphine (1-10 mg/kg, s.c.), d-amphetamine (0.3-3.2 mg/kg, i.p.), nicotine (0.1-3.2 mg/kg, s.c.), ethanol (0.6-2.4 g/kg, p.o.), caffeine (1-20 mg/kg, i.p.) and phencyclidine (0.3-5.6 mg/kg, i.p.) were studied in male Wistar rats trained to lever-press for electrical stimulation of ventral tegmental area. Morphine and d-amphetamine were the only two drugs that both decreased threshold currents and increased the maximal ratio of reinforced and non-reinforced responses. Nicotine (1 mg/kg) and ethanol (1.2 g/kg) lowered threshold currents while both decreases and increases in threshold current were seen after administration of low (5 mg/kg) and high (20 mg/kg) doses of caffeine, respectively. Nicotine, ethanol and caffeine had no effects in the progressive ratio procedure. Effects of phencyclidine did not reach levels of statistical significance in either procedure although high doses of phencyclidine disrupted performance in the progressive ratio procedure.

Effects of calcium channel blockade on intravenous self-administration of ethanol in rats

In the present study the involvement of voltage-operated calcium channels (VOCCs) in the acquisition and maintenance of operant i.v. ethanol (EtOH) self-administration was investigated in rats. Rats readily learned to self-administer EtOH (unit dose range: 0.5-4% v/v) within five daily 2-h sessions, when infusions were made contingent upon nose-poking in a hole containing infrared sensors. Response rate was related to the EtOH concentration in an inverted U-shaped manner, the maximal rate and intake being observed at a unit dose of 1% v/v (0.27 mg EtOH/infusion). Self-administration of EtOH appeared to be behaviorally specific, as responding in the reinforced hole did not coincide with increased responding in a nonreinforced hole. Daily treatment with the dihydropyridine VOCC blocker nimodipine (2.5-20 mg/kg, i.p., t-15 min) dose-dependently attenuated acquisition of EtOH self-administration; the 5 mg/kg dose resulting in a partial, and the 10 and 20 mg/kg doses in a complete prevention of i.v. self-administration behavior. The effects of nimodipine (2.5-5.0 mg/kg) were considered to be relatively specific, as an inhibition of the reinforced responding could be demonstrated in the absence of a significant effect on nonreinforced responding. When tested in rats showing stable self-administration behavior (unit dose: 1% v/v EtOH), nimodipine showed biphasic dose-response effects; with 2.5 and 5 mg/kg resulting in a mild increase, and 10 and 20 mg/kg resulting in a decrease of self-administration behavior, respectively. The present study suggests that blockade of VOCCs attenuates the reinforcing stimulus effects of EtOH; and, as such, the data may offer an explanation for the previously reported EtOH intake-reducing effects of dihydropyridine calcium channel ligands obtained in two-bottle choice paradigms. Dihydropyridine derivatives, such as nimodipine, may therefore offer an interesting approach to the pharmacotherapy of alcoholism.

Prolongation of morphine analgesia by competitive NMDA receptor antagonist D-CPPene (SDZ EAA 494) in rats

A possible future clinical application of NMDA receptor antagonists is the control of the development of opiate analgesic tolerance. Therefore, the ability of NMDA receptor antagonists to modify the acute analgesic effects of opiates becomes increasingly important. The present study sought to evaluate the analgesic potency of combined administration of morphine (5-20 mg/kg) and a competitive NMDA receptor antagonist D-CPPene (SDZ EAA 494; 3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid; 0.3-5.6 mg/kg) in the tail-flick and tail-pinch tests with rats. It was found that D-CPPene significantly increased the duration of morphine analgesia, but there was hardly any evidence for potentiation of morphine analgesia shortly after morphine administration. This effect could only in part be attributed to the D-CPPene-induced disruption of the development of 'learned hyperresponsiveness' (i.e., acquisition of decreased latencies to escape from repeated exposures to noxious stimulation). In addition, the plasma concentration of morphine was not affected by concurrent treatment with D-CPPene.

NMDA receptor antagonists prevent conditioned activation of intracranial self-stimulation in rats

Rats with bipolar electrodes implanted unilaterally into the ventral tegmental area were trained to lever-press for response contingent electrical stimulation (continuous reinforcement). After preliminary lever-press training, two types of daily sessions were held on 10 consecutive days: type T+, during which current intensity was set at the Threshold level and each response was accompanied by the visual signal (stimulus lights above the lever briefly went off); and type ST-, during which current was set at the SubThreshold level and there were no visual stimuli. On day 11, combination of the subthreshold current intensities and stimulus lights previously associated with the threshold stimulation (session type ST+) resulted in significantly elevated response rates compared to the performance under the subthreshold current without visual stimuli (session type ST-). This effect was dose dependently blocked by competitive NMDA receptor antagonist (+/-)-CPP ((+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid) and CGS 19755 (cis-4-(phosphonomethyl) piperidine-2-carboxylic acid). The present findings suggest that the activation of intracranial self-stimulation induced by a conditioned visual stimulus is dependent on the NMDA receptor functioning.

Effect of isradipine, a dihydropyridine-calcium antagonist on i.v. self-administration of morphine in rats

The effect of dihydropyridine calcium channel antagonist isradipine (PN 200-110) on morphine reinforcement has been investigated using i.v. self-administration test in rats. Rats were given the opportunity to self-administer a solution of morphine (1 mg/ml, i.v.) in a 1 hr limited access paradigm (FR = 1). Within 5-7 days rats had learned to self-administer approximately 1 mg of morphine in 1 hr as evidenced by a plateau of responding. The administration of isradipine (1.2, 2.5 and 5.0 mg/kg s.c.) 90 min before the morphine self-administration session, induced dose-dependent increase in the number of morphine self-infusions with respect to basal values. This response pattern was very similar to the one observed when morphine solution was substituted by saline in trained rats not treated with isradipine. The results indicate that isradipine inhibits partially the reinforcing properties of morphine in self-administration test.

Behavioral effects of MK-801 in morphine-dependent and non-dependent mice

The behavioral effects of MK-801 were compared in morphine-dependent and non-dependent mice. The dose of MK-801 selected for these studies was previously demonstrated to attenuate some of the morphine withdrawal signs. Subjects were repeatedly exposed to morphine (8 days, b.i.d., 10-100 mg/kg, s.c.). Twenty-four hours after last morphine injection mice received naloxone (0.1 mg/kg, s.c.) and the observation was commenced. Animals were pretreated with either MK-801 (0.1 mg/kg, i.p.) or saline 30 min prior to testing. It was found that the behavioral effects of MK-801 (decreased sociability, and increased rate of transitions between behavioral elements, locomotion, grooming) were less pronounced in morphine-dependent compared to non-dependent subjects. However, the intensified almost stereotypic eating possibly reflected increased psychotomimetic potency of MK-801 in morphine-withdrawn animals.

Isradipine inhibits nicotine intravenous self-administration in drug-naive mice

The effect of isradipine, a dihydropyridine calcium antagonist, on intravenous self-administration of nicotine in naive mice has been investigated. When nicotine injections were made contingent upon nose-poke response by naive mice, they increased their rate of nose poking with respect to animals receiving contingent saline injections or yoked control animals receiving noncontingent nicotine injections. Pretreatment of mice with mecamylamine (2.4 mg/kg) inhibited self-administration of nicotine contingent upon a nose-poke response. The same effect was observed with isradipine (0.5-1.0 mg/kg) in a dose-related manner and stereospecifically. These data suggest that isradipine suppresses the reinforcing properties of nicotine and might be useful for treatment of nicotine abuse.

Strain differences in the analgesic and reinforcing action of morphine in mice

The analgesic and reinforcing effects of morphine were compared in four strains of mice (C57BL/6, BALB/c, DBA, CBA). The analgesic action of morphine was measured in tail immersion (49 degrees C), hot plate (60 degrees C), and tail clip (four-point scale of nociceptive response) tests. The reinforcing action of morphine was studied in i.v. self-administration and conditioned place preference techniques. The results demonstrate strain differences in the analgesic and reinforcing action of morphine in mice. The relative rank order of the strains varied for the several tests as well as for the morphine effects. The lack of correlation between analgesic and reinforcing action of morphine in inbred strains supports the conclusion that analgesia and reinforcement are separate processes with different genetic control.

Excitatory amino acid receptor antagonist kynurenic acid attenuates rewarding potential of morphine

The effect of the non-selective antagonist of excitatory amino acid receptors kynurenic acid (50, 100 and 150 mg/kg, i.p.) on morphine-derived reward was studied in rats. Kynurenic acid dose dependently blocked the acquisition of morphine conditioned place preference when injected before conditioning. The expression of the previously established conditioned behavior was also blocked by the pretreatment with kynurenic acid (at the doses which do not reduce spontaneous locomotor activity) before testing. In the control experiments we failed to find that kynurenic acid alone exerts positive place preference conditioning or aversion. Kynurenic acid also attenuated the morphine-induced facilitation of responding in the intracranial self-stimulation test, causing a decrease in response rate and an increase in threshold current intensity. This effect was observed with doses at which kynurenic acid does not affect responding in the self-stimulation test by itself.

A comparison of the effects of individual organic solvents and their mixture on brain stimulation reward

In spite of the prevalence of solvent abuse, there are only a few experimental investigations on the addictive potential of household organic solvents. In the present study we attempted to investigate the influence of glue thinner, a very popular glue used by glue-sniffing children, and the four organic solvents that compose this thinner (toluene, mixture of petroleum hydrocarbons, ethyl acetate, methylene chloride) on self-stimulation of the lateral hypothalamus (ICSS) in rats. Glue thinner, toluene, a mixture of petroleum hydrocarbons, and methylene chloride had a biphasic effect on ICSS, increasing frequency of self-stimulation at lower concentrations and decreasing it at higher concentrations. Ethyl acetate decreased frequency of self-stimulation at all concentrations. In contrast to classically abused drugs, solvents increased the threshold current of self-stimulation. The differences between concentration-response curves of ICSS for glue thinner and solvents permit the proposal that the mixture of solvents can be more dangerous than the individual components in potential for inducing solvent abuse.

Experimental estimation of addictive potential of a mixture of organic solvents

In the present study we investigated in rats the reinforcing properties of glue vapours which are a mixture of four organic solvents (toluene 25%, benzine fraction 37%, ethyl acetate 31% and methylene chloride 7%). This mixture is used as a glue thinner and is a very popular among glue-sniffing children. Immediately after inhalation at a concentration of 7200 ppm, the glue vapours increased locomotor activity in the open field and response rate of self-stimulation in the lateral hypothalamus. Contrary to classical drug abuse, glue vapours enhanced the threshold current of self-stimulation. While the response rate of self-stimulation decreased to the control level 30 min after inhalation, the threshold current was still enhanced. Increasing the concentration of the vapours produced a decrease in response rate of self-stimulation and locomotor activity. When glue vapours were inhaled at a concentration of 14,400 ppm and higher, the response rate of self-stimulation was completely suppressed. The discriminative stimulus effects of the glue vapours appeared to be similar to those of general anaesthetics such as ether and pentobarbital. At vapour concentrations of 7200 and 14,400 ppm, conditioned place preference was established. The ability of solvents to reinforce conditioning in the place preference paradigm and to activate the brain reward system in intracranial self-stimulation experiments may be useful for predicting the addictive potential of inhalants.

Isradipine is able to separate morphine-induced analgesia and place conditioning

The effect of isradipine, a dihydropyridine calcium antagonist, on morphine-induced place preference and analgesia in rats and mice was studied. Isradipine (0.6-5.0 mg/kg s.c.) inhibited an acquisition of morphine-induced place preference in rats and mice in a dose-related manner. Isradipine did not affect or strengthen morphine-induced analgesia as measured by tail-clip and hot-plate tests in mice and tail-clip and tail-flick tests in rats. The results suggest that analgesic and reinforcing effects of morphine might be pharmacologically separated by isradipine.

Calcium antagonists isradipine and nimodipine suppress cocaine and morphine intravenous self-administration in drug-naive mice

The effect of isradipine and nimodipine, two dihydropyridine calcium antagonists, on intravenous self-administration of cocaine and morphine in naive mice has been investigated. When morphine or cocaine injections were made contingent upon nose-poke response by naive mice, they increased their rate of nose-poking with respect to animals receiving contingent saline injections or yoked control animals, receiving noncontingent cocaine or morphine injections. Pretreatment of mice with isradipine (1.0-3.0 mg/kg, SC) or nimodipine (5-20 mg/kg, SC) inhibited in a dose-related manner self-administration both of cocaine and morphine contingent upon a nose-poke response. The ED50 of isradipine against cocaine and morphine self-administration was 1.7 and 2.1 mg/kg, respectively. The relative values for nimodipine were 14.5 and 11.4 mg/kg, respectively. These data suggest that nimodipine and, especially, isradipine suppress the reinforcing properties of morphine and cocaine and may be an effective pharmacotherapy for treatment of cocaine and heroin abuse.