Comparison of Direct and Indirect Detection of Toxoplasma gondii in Ovine Using Real-Time PCR, Serological and Histological Techniques.

Toxoplasma gondii is a zoonotic pathogen and the ingestion of tissue cysts by consumption of lamb or mutton has been identified as a possible cause of infection in humans. Many serological surveys in sheep have been performed, showing relevant serological rates; however, while the detection of antibodies indicates an exposure to T. gondii, this does not necessarily imply the presence of tissue cysts in edible tissue. The current study aims to provide further understanding on the occurrence of T. gondii in sheep muscles and the strength of correlation between serological positivity and presence of the parasite in sheep. From 349 sheep, samples (i.e., blood, heart and diaphragm) were collected and subjected to ELISA tests, real-time PCR and histological tests. Despite the high seroprevalence, T. gondii DNA was detected in the heart and/or the diaphragm from 13 out of the 349 tested sheep (3.7%); all were adults (13/191). Furthermore, the histological tests did not reveal the presence of T. gondii tissue cysts in any of the examined portions of interventricular septum. It should be considered that the likelihood of detecting genetic material of the parasite is probably influenced by the uneven distribution of the tissue cysts in the carcass as well as the methodology applied. The findings of this study support the importance of describing the uncertainty associated with the data used for risk assessment to reduce inaccurate estimation or risk overestimation.

Toxoplasma gondii in sheep: Serological occurrence at slaughterhouse level in Italy and environmental risk factors.

Toxoplasmosis is a parasitic disease affecting a wide range of species, including humans, and can be responsible for important clinical manifestations such as abortion and neurological signs. Sheep show a remarkable susceptibility to its causative agent, Toxoplasma gondii, and zoonotic transmission may occur in case of consumption of undercooked meat obtained from infected animals. Toxoplasma gondii seroprevalence in sheep can significantly vary on a geographical basis, as shown by numerous surveys conducted worldwide. To investigate environmental and climate conditions that may affect the likelihood of ovine infection, 405 serum samples from selected sheep raised in 91 farms were collected from two abattoirs, with each abattoir receiving animals from two regions (1/Tuscany-Latium and 2/Campania-Basilicata). The seroprevalence of infection in all examined animals was 53.8%. Young animals (n = 165) had a lower likelihood of being T. gondii positive compared to the adults (OR = 0.21), and the seropositive rate of animals slaughtered in abattoir 2 was significantly higher than that of animals slaughtered in abattoir 1 (60.5 vs. 43.2%, p < 0.01). The significant bioclimatic variables (p < 0.05) associated with the presence of T. gondii antibodies were related to areas with a lower range of temperature and higher precipitation. In conclusion, this study expands on the interpretation of serological data, with the inclusion of environmental and climatic variables, as possible risk factors in the spread of toxoplasmosis in the study area. These findings provide novel insights to support public health measures, such as risk-based control plan, and contribute to a "One Health" approach, taking into account the environmental and climatic perspectives.

Primary Gliosarcoma of the Cerebellum in a Young Pregnant Woman: Management Challenges and Immunohistochemical Features.

BACKGROUND: Gliosarcoma (GS) represents a rare, high-grade (WHO Grade IV), central nervous system neoplasm, characterized by a very poor prognosis. Similar to other high-grade gliomas, GS affects mainly adults in the 5th-7th decade of life and presents a higher incidence in males. The most reported locations of GS are the temporal lobe and the frontal lobe, while only eight cases of GS originating from the posterior cranial fossa are reported in the literature. CASE DESCRIPTION: We report the first case occurring during pregnancy in a 33-year-old patient. Diagnosis was obtained on the 15th week of gestation when patient presented with signs and symptoms of life-threatening raised intracranial pressure. Surgical excision was followed by early recurrence and eventually disease progression because the patient refused adjuvant treatment to save her fetus. CONCLUSIONS: GS should be considered in the differential diagnosis of posterior cranial fossa tumors with radiological features of meningioma or glioblastoma, even in young patients. To this regard, sarcomas, solitary fibrous tumors, and even metastases should be considered, especially in light of the tendency of GS to give rise to extracranial localizations. Whenever an aggressive management with radical excision and adjuvant treatment is not safely achievable, disease progression is likely to be unavoidable.

Prevalence of prothrombotic polymorphisms in a selected cohort of cryptogenic and noncryptogenic ischemic stroke patients.

Ischemic stroke is a complex multifactorial disease and approximately 30%, especially in the young, are cryptogenic. In some of the patients with cryptogenic ischemic stroke the underlying risk factor may be a prothrombotic state. We studied 101 patients with ischemic stroke under 55 years of age. All the patients underwent an extensive diagnostic evaluation to determine the cause of stroke. Common variations in the genes encoding factor V, prothrombin, 5,10-methylenetetrahydrofolate reductase, plasminogen activator inhibitor-1, and human platelet alloantigens-1 were evaluated. Of the 101 patients with ischemic stroke, 28 patients had cryptogenic ischemic stroke. At least one of the different genetic polymorphisms investigated was present in 44% patients in the total group and in 48% of patients with cryptogenic ischemic stroke. In this study population under 55 years of age there was no significant difference in the prevalence of various genetic polymorphisms, factor V, prothrombin, 5,10-methylenetetrahydrofolate reductase, plasminogen activator inhibitor-1, and human platelet alloantigens) in patients with cryptogenic ischemic stroke and in patients with ischemic stroke of determined cause.

Long-term survival and outcome after first stroke in the Sicilian Aeolian Island Archipelago population.

BACKGROUND: Only a restricted number of population studies based on long-term prognosis after a stroke have been published. We analyzed long-term survival and outcome in insular first-ever stroke population from the Aeolian Archipelago. SUBJECTS AND METHODS: From 1 July, 1999 to 30 June 2002, 62 patients with first-ever stroke were recruited to evaluate short-term incidence and outcome. Information for every patient was collected by phone interviews after 3 months, 1 year, and 4 years. RESULTS: 30 days case fatality rate was 24.2% (95% C.I. 14.22 to 36.75). Fifty-one percent (95% C.I. 35.8 to 66.3) of patients died before last survey and 39.1% died during the first year of follow-up. Annual approximate death risk amounted to about 10%. The cerebrovascular causes were the most frequent causes of death (65.2%). A high level of invalidity at 4 years was present in many survivors (40%). None of the deceased had followed physio-kinesitherapy, or applied for equipment or services. CONCLUSION: More attentive medical care for stroke patients could help improve outcome, reducing mortality for patients from the Aeolian island, who already showed a low incidence.

The neuroanatomical plates of Guido da Vigevano.

Guido da Vigevano was an Italian physician and engineer who lived in the 13th and 14th centuries. He was the first scientist who used pictures to illustrate his anatomical descriptions, developing for the first time a close relationship between anatomical studies and artistic drawings. This was further developed in the Renaissance. In his textbook Anathomia are displayed six plates showing for the first time neuroanatomical structures and techniques: dissection of the head by means of trephination, and depictions of the meninges, cerebrum, and spinal cord. On the surface of the brain painting it is possible to recognize a vague patterning of cortical convolutions. Ventricles are also described and shown. This book constituted the first attempt in the history of neuroscience to illustrate an anatomical description with schematic pictures to achieve a better understanding of such complex structures.

Long-term evolution of EEG in Unverricht-Lundborg disease.

PURPOSE: Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy characterized by myoclonus, epilepsy, and ataxia, without major cognitive decline. There is no systematic study on the long-term evolution of EEG in this condition. PATIENTS AND METHODS: Twenty-five patients with ULD who came to our observation before 1995 and periodically followed in our Epilepsy Centres were included. All waking EEG traces were visually reviewed for the characterization background activity, with particular regard to the frequency of the posterior dominant rhythm (PR), and for the occurrence of spontaneous generalized spike or polyspike and wave discharges (GSWD) and photoparoxysmal response (PPR). Sleep recordings were analyzed with particular regard to the preservation of the physiological sleep patterns and the occurrence of GSWD and other epileptic abnormalities. RESULTS: PR was normal in 68% of patients at the beginning of the disease and kept stable over the years. GSWD were present in 92% of patients at the onset of the disease and gradually disappeared during the follow-up with a significant difference (p<0.001) after the 15th year of disease. PPR was present in 88% of patients at the disease onset and gradually disappeared with a significant difference (p<0.001) after the 10th year of disease. A gradual reduction of GSWD and a progressive disappearance of physiological sleep patterns were observed in sleep EEGs. CONCLUSION: In patients with ULD followed for an extended period of time, EEG shows no relevant deterioration of BA while a gradual reduction of GSWD and PPR is observed over time, well correlating with the good seizure outcome in this condition.

Baclofen-induced suppression of alcohol deprivation effect in Sardinian alcohol-preferring (sP) rats exposed to different alcohol concentrations.

This study investigated the effect of the gamma-aminobutyric acid(B) (GABA(B)) receptor agonist, baclofen, on alcohol deprivation effect (the transient increase in alcohol intake occurring after a period of alcohol abstinence) in Sardinian alcohol-preferring (sP) rats exposed to 4 bottles containing water and 10%, 20%, and 30% (v/v) alcohol, respectively. Acute administration of baclofen (1 mg/kg, i.p.) suppressed both aspects of alcohol deprivation effect: the extra-intake of alcohol and the selection of the highest concentrated alcohol solution. These results suggest that the GABA(B) receptor is part of the neural substrate mediating alcohol deprivation in sP rats.

Identification of miltirone as active ingredient of Salvia miltiorrhiza responsible for the reducing effect of root extracts on alcohol intake in rats.

BACKGROUND: Previous work found that extracts from the roots of Salvia miltiorrhiza, a Chinese medicinal herb, reduced alcohol intake in selectively bred Sardinian alcohol-preferring (sP) rats. The present study was designed to evaluate whether miltirone, one of the possible active constituents of S. miltiorrhiza, might be responsible for the reducing effect of the extracts on alcohol intake. METHODS: An initial experiment assessed the effect of 100 mg/kg (intragastric, i.g.) of 4 extracts of S. miltiorrhiza, differing in miltirone content (0, 2, 3, and 7%, respectively), on alcohol intake in alcohol-experienced sP rats exposed to the 2-bottle "alcohol (10%, volume in volume) versus water" choice regimen. Subsequently, the effect of pure miltirone (2.5-10 mg/kg, i.g., i.e., a dose range comparable to its content in the effective doses of the active extracts) on acquisition and maintenance of alcohol-drinking behavior was evaluated in alcohol-naive and alcohol-experienced sP rats exposed to the 2-bottle choice regimen. The effect of miltirone (10 mg/kg, i.g.) on blood alcohol levels was assessed after the i.g. and intraperitoneal (i.p.) administration of alcohol. Finally, the effect of miltirone (30-100 mg/kg, i.g.) on the severity of alcohol withdrawal syndrome was evaluated in Wistar rats made physically dependent on alcohol by the repeated administration of intoxicating doses of alcohol. RESULTS: The reducing effect of 4 different extracts of S. miltiorrhiza on alcohol intake was positively and significantly correlated with their miltirone content. Pure miltirone reduced alcohol intake in alcohol-experienced rats and delayed acquisition of alcohol-drinking behavior in alcohol-naive rats. Similar to S. miltiorrhiza extracts, miltirone markedly reduced blood alcohol levels when alcohol was administered i.g. but not i.p., suggesting that miltirone hampered alcohol absorption from the gastrointestinal system. Finally, miltirone failed to affect the severity of alcohol withdrawal syndrome in alcohol-dependent rats. CONCLUSIONS: The results of the present study suggest that miltirone is the likely active constituent of S. miltiorrhiza responsible for the reducing effect of its extracts on alcohol intake in different experimental models of excessive alcohol consumption.

Baclofen-induced reduction of alcohol reinforcement in alcohol-preferring rats.

Recent studies have demonstrated that treatment with the gamma-aminobutyric acid (GABA(B)) receptor agonist, baclofen, reduces alcohol intake in selectively bred Sardinian alcohol-preferring rats tested under the homecage two-bottle "alcohol versus water" choice regimen. This study was designed to investigate whether baclofen also reduces alcohol-reinforcing effects in Sardinian alcohol-preferring rats. To this aim, sP rats were trained to lever press for oral alcohol (15%, vol/vol) or sucrose (0.3%, wt/vol; included as alternative reinforcer to evaluate the specificity of baclofen effect on alcohol reinforcement) under a fixed ratio schedule of 4. Once steady levels of alcohol or sucrose self-administration behavior were established, the effects of acutely administered baclofen (0, 1.7, and 3 mg/kg, intraperitoneal [ip]) and naloxone (0, 1, and 3 mg/kg, ip; included as reference compound) on alcohol- or sucrose-reinforced responding were evaluated. Baclofen administration dose dependently, although not specifically, reduced alcohol-reinforced responding to an extent comparable to that of naloxone. Baclofen also produced a dose-dependent and specific delay in the onset of alcohol-reinforced responding, suggesting that it suppressed the rats' motivation to start drinking alcohol. These data are discussed in terms of adding further support to the hypothesized involvement of the GABA(B) receptor in the neural system mediating alcohol reinforcement. These data are also in agreement with the results of recent preliminary clinical studies suggesting that baclofen may have therapeutic efficacy in the treatment of alcohol dependence.

Prevalence and characteristics of epilepsy in the Aeolian islands.

PURPOSE: To estimate the prevalence and define the clinical characteristics of epileptic disorders in the 13,431 residents of the Sicilian Aeolian archipelago, on June 1, 1999. METHODS: All established or suspected cases were identified by the neurologists of our working group from available medical information sources. Possible epilepsy cases were then evaluated by the epileptologists by using a standardized questionnaire. The patients were further reviewed by the whole research team to confirm the clinical diagnosis. For a more detailed syndromic definition, some patients underwent EEG or neuroradiologic investigations or both. RESULTS: The crude point prevalence rate of active epilepsy was 3.13 (95% confidence interval, 2.2-4.2). The prevalence rate age-adjusted to the 2001 Italian population was 3.01. Females had a slightly higher prevalence rate than did males. The highest age-specific prevalence was found in patients aged 5 to 14 years (5.05) and in those aged 65 to 74 years (5.41). Partial seizures with or without secondary generalization were more common (61.7%) than were generalized seizures. Eighty-three percent of cases had symptomatic or cryptogenic localization-related epilepsies, and 8.5% had idiopathic (generalized or partial) epilepsies. Epilepsy was unclassified in 8.5% of cases. CONCLUSIONS: The prevalence of active epilepsy in the Aeolian islands is lower than that in other developed areas, including northern Italy, but is similar to that in Sicily. Partial seizures were the most common type, and localization-related symptomatic epilepsies were the largest syndromic category.

First-ever stroke incidence and 30-day case fatality in the Sicilian Aeolian archipelago, Italy.

BACKGROUND AND PURPOSE: Not many data on stroke epidemiology come from studies on islands. This is the first report on a Mediterranean archipelago population. METHODS: Using recommended criteria, from July 1, 1999, to June 30, 2002, information was collected on first-ever stroke and 30-day case fatality in Aeolian island residents (13,431). RESULTS: The overall crude incidence rate was 154 of 100,000 (95% CI, 118 to 197; 128 in men and 180 in women) or 180, 154, and 87, if adjusted to the Italian, European, and world populations, respectively. The 30-day case fatality rate was 24.2% (95% CI, 14.22 to 36.75). CONCLUSIONS: Besides genetic or dietary factors, our results may reflect local, limited possibilities of diagnosis and management for stroke patients.

Endocannabinoid system and alcohol addiction: pharmacological studies.

The present paper describes the results of recent pharmacological studies implicating the cannabinoid CB1 receptor in the neural circuitry regulating alcohol consumption and motivation to consume alcohol. Cannabinoid CB1 receptor agonists have been found to specifically stimulate alcohol intake and alcohol's motivational properties in rats. Conversely, the cannabinoid CB1 receptor antagonist, SR 141716, has been reported to specifically suppress acquisition and maintenance of alcohol drinking behavior, relapse-like drinking and alcohol's motivational properties in rats. More recent data indicate that opioid receptor antagonists a) blocked the stimulatory effect of cannabinoids on alcohol intake, and b) synergistically potentiated the suppressing effect of SR 141716 on alcohol intake and alcohol's motivational properties. Consistently, SR 141716 blocked the stimulatory effect of morphine on alcohol intake. These results suggest a) the existence of a functional link between the cannabinoid and opioid receptor systems in the control of alcohol intake and motivation to consume alcohol, and b) that novel and potentially effective therapeutic strategies for alcoholism may come from the combination of cannabinoid and opioid receptor antagonists.

Effect of the combination of naltrexone and baclofen, on acquisition of alcohol drinking behavior in alcohol-preferring rats.

Recent surveys suggest that positive outcomes in the pharmacotherapy of alcoholism may be obtained through drug combinations. The present study evaluated the effect of the combination of the opioid receptor antagonist, naltrexone, with the GABA(B) receptor agonist, baclofen, on the acquisition of alcohol drinking behavior in Sardinian alcohol-preferring (sP) rats. Rats were treated with either saline, 0.5 mg/kg naltrexone, 1mg/kg baclofen, or 0.5 mg/kg naltrexone plus 1mg/kg baclofen once a day for 10 days. Alcohol was offered immediately after the first drug injection under the 2-bottle regimen. Alcohol intake in saline-treated rats rose to 5-6 g/kg/day within a few days, indicative of a rapid acquisition of alcohol drinking behavior. Neither naltrexone nor baclofen, when given alone, affected alcohol drinking behavior. In contrast, the drug combination resulted in a significant reduction in daily alcohol intake and retardation in the acquisition of alcohol drinking behavior. These results suggest that combination of naltrexone plus baclofen may result in a synergistic reduction in alcohol intake in sP rats. These results are discussed in terms of naltrexone and baclofen exerting a concomitant and reciprocally potentiating inhibitory action on alcohol-induced activation of mesolimbic dopamine transmission.

Suppressing effect of the cannabinoid CB1 receptor antagonist, SR147778, on alcohol intake and motivational properties of alcohol in alcohol-preferring sP rats.

AIMS: The present study investigated the effect of the newly synthesized cannabinoid CB(1) receptor antagonist, SR147778, on alcohol intake and the motivational properties of alcohol in selectively bred Sardinian alcohol-preferring (sP) rats. METHODS AND RESULTS: In Experiment 1, the repeated administration of SR147778 (0.3-3 mg/kg twice daily, i.p.) specifically suppressed the acquisition of alcohol drinking behaviour in alcohol-naive rats exposed to the two-bottle "alcohol vs water" choice regimen for 24 h/day. In Experiment 2, an acute administration of SR147778 (2.5-10 mg/kg, i.p.) specifically reduced alcohol intake in alcohol-experienced rats that were given alcohol and water under the two-bottle choice regimen in daily sessions of 4 h. In Experiment 3, an acute administration of SR147778 (0.3-3 mg/kg, i.p.) suppressed the "alcohol deprivation effect", i.e. the extra-intake of alcohol occurring after a period of alcohol abstinence. In Experiment 4, an acute administration of SR147778 (0.3-3 mg/kg, i.p.) specifically suppressed the extinction responding for alcohol, i.e. the maximal number of lever responses reached in the absence of alcohol in rats trained to lever-press for alcohol (measure of the motivational properties of alcohol). In Experiment 5, the combination of 3 mg/kg of SR147778 (i.p.) and 0.5 g/kg of alcohol (i.p.), a dose comparable with those usually consumed by sP rats in each drinking binge, failed to induce any conditioned taste aversion. CONCLUSION: Taken together, these results extend to SR147778 the anti-alcohol profile of the prototype cannabinoid CB(1) receptor antagonist, rimonabant (SR141716), and strengthen the hypothesis that the cannabinoid CB(1) receptor is part of the neural substrate mediating alcohol intake and the motivational properties of alcohol.

Role of GABA(B) receptor in alcohol dependence: reducing effect of baclofen on alcohol intake and alcohol motivational properties in rats and amelioration of alcohol withdrawal syndrome and alcohol craving in human alcoholics.

The present paper describes the results of recent preclinical and clinical studies conducted in this laboratory in order to characterize the anti-alcohol properties of the GABA(B) receptor agonist, baclofen. At a preclinical level, the repeated administration of non-sedative doses of baclofen dose-dependently suppressed the acquisition and maintenance of alcohol drinking behavior in selectively bred Sardinian alcohol-preferring (sP) rats tested under the homecage, 2-bottle "alcohol vs water" choice regimen. Acute injection of baclofen completely blocked the temporary increase in voluntary alcohol intake occurring after a period of alcohol abstinence (the so-called alcohol deprivation effect, which models alcohol relapses in human alcoholics). Acute treatment with baclofen also dose-dependently suppressed extinction responding for alcohol (an index of motivation to consume alcohol) in sP rats trained to lever-press for oral alcohol self-administration. Taken together, these results suggest the involvement of the GABA(B) receptor in the neural substrate mediating alcohol intake and alcohol motivational properties in an animal model of excessive alcohol consumption. Further, acutely administered baclofen dose-dependently reduced the severity of alcohol withdrawal signs in Wistar rats made physically dependent upon alcohol. Preliminary clinical surveys suggest that the anti-alcohol properties of baclofen observed in rats may generalize to human alcoholics. Indeed, a double-blind survey demonstrated that repeated daily treatment with baclofen was associated, when compared to placebo, with a higher percentage of subjects totally abstinent from alcohol and a higher number of days of total abstinence. Treatment with baclofen also suppressed the number of daily drinks and decreased the obsessive and compulsive components of alcohol craving. Finally, a single non-sedative dose of baclofen resulted in the rapid disappearance of alcohol withdrawal symptomatology, including delirium tremens, in alcohol-dependent patients. In both clinical studies, baclofen was well tolerated with minimal side effects. These results suggest that baclofen may represent a potentially effective medication in the treatment of alcohol-dependent patients.

Suppressing effect of the cannabinoid CB1 receptor antagonist, SR 141716, on alcohol's motivational properties in alcohol-preferring rats.

Administration of the cannabinoid CB(1) receptor antagonist, SR 141716 [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide], has been reported to reduce alcohol intake and alcohol self-administration in different models of excessive alcohol consumption, including the selectively bred Sardinian alcohol-preferring (sP) rats. The present study investigated whether SR 141716 was also capable of decreasing, in this rat line, alcohol's motivational properties. Extinction responding for alcohol, defined as the maximal number of lever responses reached in the absence of alcohol in rats trained to lever-press for alcohol, was used as index of alcohol's motivational properties. Rats were initially trained to lever-press for oral alcohol (15%, v/v) under a fixed ratio (FR) schedule of FR4. Once self-administration behavior was established, extinction sessions were conducted. SR 141716 (0, 0.3, 1 and 3 mg/kg; i.p.) was acutely administered before extinction sessions. In order to assess the specificity of SR 141716 action on extinction responding for alcohol, a separate group of sP rats was trained to lever-press for a 3% (w/v) sucrose solution under an FR4 schedule. SR 141716 administration produced a dose-dependent, virtually complete suppression of extinction responding for alcohol. In contrast, extinction responding for sucrose was not significantly altered by treatment with SR 141716. Further to the consummatory aspects, these results also extend the suppressing effect of SR 141716 to the appetitive aspects of alcohol drinking behavior in sP rats. The results also implicate the cannabinoid CB1 receptor in the neural substrate mediating alcohol's motivational properties in this rat line.

Suppression by baclofen of the stimulation of alcohol intake induced by morphine and WIN 55,212-2 in alcohol-preferring rats.

Administration of morphine and cannabinoids stimulates alcohol intake in rats. The present study investigated whether the promoting effect of morphine and of the cannabinoid receptor agonist, WIN 55,212-2 [(R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone], on alcohol intake was prevented by the gamma-aminobutyric (GABA)(B) receptor agonist, baclofen. Sardinian alcohol-preferring (sP) rats were given alcohol (10%, v/v) and water under the standard homecage two-bottle-free choice regimen with unlimited access for 24 h/day. Baclofen (0, 0.5 and 1 mg/kg; i.p.) was administered acutely 30 min before lights off. Morphine (0 and 1 mg/kg, s.c.) or WIN 55,212-2 (0 and 2 mg/kg, i.p.) was administered acutely 10 min after baclofen. Alcohol intake was recorded 60 min after lights off. As predicted, both morphine and WIN 55,212-2 produced a specific and marked increase in alcohol intake. Pretreatment with baclofen, which failed to alter alcohol intake when given alone, dose-dependently suppressed morphine- and WIN 55,212-2-induced promotion of alcohol drinking. These results suggest the involvement of the GABA(B) receptor in the neural circuitry mediating the stimulating effect of morphine and cannabinoids on alcohol consumption in sP rats.

Suppression of GABA(B) receptor function in vivo by disulfide reducing agent, DL-dithiothreitol (DTT).

RATIONALE: A recent in-vitro study demonstrated that the potent disulfide reducing agent, DL-dithiothreitol (DTT), may alter the structural stability of the GABA(B) receptor, probably inactivating the disulfide bonds between four cysteine residues located in the GABA(B1(a)) receptor structure. OBJECTIVES: The present study was designed to evaluate whether DTT treatment was capable of antagonizing some behavioral effects of pharmacological stimulation of the GABA(B) receptor. METHODS: Experiments on sedation/hypnosis induced by the GABA(B) receptor agonists baclofen, SKF 97541, CGP 44532 and gamma-hydroxybutyric acid (GHB) in DBA mice and selectively bred GHB-sensitive (GHB-S) rats, and a GHB drug discrimination study in Long Evans rats were conducted. Specificity of the DTT action on the GABA(B) receptor was investigated by assessing its effect on the sedative/hypnotic effect induced by diazepam, ketamine and ethanol. RESULTS: DTT prevented the sedative/hypnotic effect of all GABA(B) receptor agonists tested and also reversed baclofen-induced sedation/hypnosis. In contrast, DTT had no effect on, or even potentiated, sedation/hypnosis produced by diazepam, ketamine or ethanol. DTT completely blocked the discriminative stimulus effects of GHB. CONCLUSIONS: These results are discussed in terms of DTT altering the stability of the binding domain of the GABA(B) receptor, hindering the drug-receptor interaction.