Anti-Alcohol and Anxiolytic Properties of a New Chemical Entity, GET73

N-[(4-trifluoromethyl)benzyl]4-methoxybutyramide (GET73) is a newly synthesized compound structurally related to the clinically used, alcohol-substituting agent, gamma-hydroxybutyric acid (GHB). The present study was designed to assess whether GET73 may share with GHB the capacity to reduce alcohol intake in rats. Additionally, the effect of treatment with GET73 on anxiety-related behaviors and cognitive tasks in rats was investigated. A series of in vitro binding assays investigated the capacity of GET73 to bind to the GHB binding site and multiple other receptors. GET73 (10−9–10−3 M) failed to inhibit [3H]GHB binding at both high- and low-affinity GHB recognition sites in rat cortical membranes. GET73 displayed minimal, if any, binding at dopamine, serotonin, GABA, and glutamate receptors in membranes from different rat brain areas. Acute treatment with low-to-moderate, non-sedative doses of GET73 (5–50 mg/kg, i.g. or i.p.) (a) reduced alcohol intake and suppressed “alcohol deprivation effect” (a model of alcohol relapse) in selectively bred, Sardinian alcohol-preferring (sP) rats, (b) exerted anxiolytic effects in Sprague-Dawley (SD) and sP rats exposed to the Elevated Plus Maze test, and (c) tended to induce promnestic effects in SD rats exposed to a modified water version of the Hebb–Williams maze test. Although the mechanism of GET73 action is currently unknown, the results of the present study suggest that GET73 has a multifaceted pharmacological profile, including the capacity to reduce alcohol drinking and anxiety-related behaviors in rats

Reduction by the Positive Allosteric Modulator of the GABAB Receptor, GS39783, of Alcohol Self-Administration in Sardinian Alcohol-Preferring Rats Exposed to the “Sipper” Procedure

The present study was designed to evaluate (a) alcohol self-administration behavior of selectively bred, Sardinian alcohol-preferring (sP) rats exposed to the so-called “sipper” procedure (characterized by the temporal separation between alcohol-seeking and -taking phases), and (b) the effect of the positive allosteric modulator of the GABAB receptor, GS39783, on alcohol self-administration in sP rats exposed to this procedure. To this end, sP rats were initially trained to lever-respond under a reinforcement requirement (RR) 55 (RR55) for alcohol. Achievement of RR55 resulted in the 20-min presentation of the alcohol (15%, v/v)-containing sipper bottle. Once stable levels of lever-responding and alcohol consumption were reached, rats were treated with 0, 25, 50, and 100 mg/kg GS39783 (i.g.) 60 min before the self-administration session. Rats displayed robust alcohol-seeking (as suggested by relatively short latencies to the first lever-response and high frequencies of lever-responding) and -taking (as suggested by alcohol intakes averaging approximately 1.5 g/kg) behaviors. Pretreatment with GS39783 inhibited both alcohol-seeking (the number of rats achieving RR55 and the mean RR value were virtually halved) and -taking (the amount of self-administered alcohol was reduced by approximately 60%). The results of the present study suggest the power of the “sipper” procedure in triggering high levels of alcohol-seeking and -taking behavior in sP rats. Further, these results extend to this additional procedure of alcohol self-administration the capacity of GS39783 to reduce the motivational properties of alcohol and alcohol consumption in sP rats

Activation of the GABAB Receptor Prevents Nicotine-Induced Locomotor Stimulation in Mice

Recent studies demonstrated that activation of the GABAB receptor, either by means of orthosteric agonists or positive allosteric modulators (PAMs), inhibited different nicotine-related behaviors, including intravenous self-administration and conditioned place preference, in rodents. The present study investigated whether the anti-nicotine effects of the GABAB receptor agonist, baclofen, and GABAB PAMs, CGP7930, and GS39783, extend to nicotine stimulant effects. To this end, CD1 mice were initially treated with baclofen (0, 1.25, and 2.5 mg/kg, i.p.), CGP7930 (0, 25, and 50 mg/kg, i.g.), or GS39783 (0, 25, and 50 mg/kg, i.g.), then treated with nicotine (0 and 0.05 mg/kg, s.c.), and finally exposed to an automated apparatus for recording of locomotor activity. Pretreatment with doses of baclofen, CGP7930, or GS39783 that did not alter locomotor activity when given with nicotine vehicle fully prevented hyperlocomotion induced by 0.05 mg/kg nicotine. These data extend to nicotine stimulant effects the capacity of baclofen and GABAB PAMs to block the reinforcing, motivational, and rewarding properties of nicotine. These data strengthen the hypothesis that activation of the GABAB receptor may represent a potentially useful, anti-smoking therapeutic strategy

Reducing Effect of Saikosaponin A, an Active Ingredient of Bupleurum falcatum, on Intake of Highly Palatable Food in a Rat Model of Overeating

Recent lines of experimental evidence have indicated that saikosaponin A (SSA)—a bioactive ingredient of the medicinal plant, Bupleurum falcatum L.—potently and effectively reduced operant self-administration of chocolate and reinstatement of chocolate-seeking behavior in rats. The present study was designed to assess whether the protective properties of SSA on addictive-like, food-related behaviors generalize to a rat model of overeating of palatable food. To this end, rats were habituated to feed on a standard rat chow for 3 h/day; every 4 days, the 3-h chow-feeding session was followed by a 1-h availability of highly palatable, calorie-rich Danish butter cookies or Oreo chocolate cookies. Even though fed, rats consumed large amounts of cookies; intake of calories from cookies (consumed in 1 h) was even larger than that of calories from chow (consumed in 3 h). SSA (0, 0.25, 0.5, and 1 mg/kg, i.p.) was administered 10 min before cookie presentation. Treatment with SSA resulted in a dose-related decrease in intake of both butter and chocolate cookies. Administration of the cannabinoid CB1 receptor antagonist/inverse agonist, rimonabant (0, 0.3, 1, and 3 mg/kg, i.p.; tested as reference compound), produced a similar reduction in intake of butter cookies. These results (a) contribute to the set-up and validation of a rat model of overeating, characterized by the intake of large amounts of unnecessary calories and (b) provide an additional piece of evidence to the anorectic profile of SSA in rats

Suppression by gamma-hydroxybutyric acid of alcohol deprivation effect in rats: Preclinical evidence of its anti-relapse properties

Gamma-hydroxybutyric acid (GHB) reduces (a) alcohol intake and alcohol motivational properties in alcohol-preferring rats and (b) alcohol drinking and craving for alcohol in human alcoholics. The present study was designed to extend to relapse-like drinking the capacity of GHB to suppress different alcohol-related behaviors in alcohol-preferring rats. The alcohol deprivation effect, defined as the temporary increase in alcohol intake occurring in laboratory animals after a period of alcohol deprivation, was used as model of alcohol relapse. Acute administration of non-sedative doses of GHB (0, 100, 200, and 300 mg/kg, i.p.) resulted in the complete suppression of the extra-amount of alcohol consumed by Sardinian alcohol-preferring (sP) rats during the first hour of re-access to alcohol after a 14-day period of deprivation. These data demonstrate that GHB suppressed relapse-like drinking in a rat model of excessive alcohol consumption

High alcohol intake in female Sardinian alcohol-preferring rats

Sardinian alcohol-preferring (sP) rats have been selectively bred for high alcohol preference and consumption. When exposed to the standard, home cage 2-bottle “alcohol (10%, v/v) vs. water” choice regimen with continuous access, male sP rats consume daily approximately 6 g/kg alcohol. Conversely, when exposed to the intermittent (once every other day) access to 2 bottles containing alcohol (20%, v/v) and water, respectively, male sP rats display marked increases in daily alcohol intake and signs of alcohol intoxication and “behavioral” dependence. The present study was designed to assess alcohol intake in female sP rats exposed, under the 2-bottle choice regimen, to (a) 10% (v/v) alcohol with continuous access (CA10%), (b) 10% (v/v) alcohol with intermittent access (IA10%), (c) 20% (v/v) alcohol with continuous access (CA20%), and (d) 20% (v/v) alcohol with intermittent access (IA20%). Male sP rats (exposed to CA10% and IA20% conditions) were included for comparison. Over 20 daily drinking sessions, daily alcohol intake in female CA10% and IA20% rats averaged 7.0 and 9.6 g/kg, respectively. The rank of alcohol intake was IA20% > IA10% ¼ CA20% > CA10%. Conversely, daily alcohol intake in male CA10% and IA20% rats averaged 6.0 and 8.2 g/kg, respectively. Comparison of female and male rats yielded the following rank of alcohol intake: female IA20% > male IA20% > female CA10% male CA10%. An additional experiment found that alcohol drinking during the first hour of the drinking session produced mean blood alcohol levels of 35e40 mg% and 85e100 mg% in the CA10% and IA20% rats, respectively. These results (a) extend to female sP rats previous data demonstrating the capacity of the IA20% condition to markedly escalate alcohol drinking, and (b) demonstrate that female sP rats consume more alcohol than male sP rats. This sex difference is more evident under the IA20% condition, suggesting that female sP rats are highly sensitive to the promoting effect of the IA20% condition on alcohol drinking. These data contribute to the characterization of sP rats as a model of excessive alcohol consumption

Reducing effect of saikosaponin A, an active ingredient of Bupleurum falcatum, on alcohol self-administration in rats: Possible involvement of the GABAB receptor

Recent studies demonstrated that treatment with saikosaponin A (SSA) - an active ingredient of the medicinal herb, Bupleurum falcatum L. - selectively suppressed, likely via a GABAB receptor-mediated mechanism, intravenous self-administration of morphine and cocaine in rats [Yoon et al., 2012; 2013]. The present study was designed to investigate whether the capacity of SSA to suppress morphine and cocaine self-administration extends to oral alcohol self-administration. To this end, selectively bred Sardinian alcohol-preferring (sP) rats were trained to lever-respond on a Fixed Ratio (FR) 4 (FR4) schedule of reinforcement for alcohol (15%, v/v) in daily 30-min sessions. Once responding had stabilized, rats were tested under the FR4 (measure of alcohol reinforcing properties) and Progressive Ratio (PR; measure of alcohol motivational properties) schedules of reinforcement. The possible involvement of the GABAB receptor system was investigated testing the effect of (a) pretreatment with the GABAB receptor antagonist, SCH50911, and (b) combined treatment with the positive allosteric modulator of the GABAB receptor, GS39783. Treatment with SSA (0, 0.25, 0.5, and 1 mg/kg, i.p.) markedly reduced lever-responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). Pretreatment with 2 mg/kg SCH50911 (i.p.) resulted in a partial blockade of the reducing effect of 0.5 mg/kg SSA on lever-responding for alcohol and amount of self-administered alcohol. Combination of per se ineffective doses of GS39783 (5 mg/kg, i.g.) and SSA (0.1 mg/kg, i.p.) reduced lever-responding for alcohol and amount of self-administered alcohol. These results (a) extend to alcohol self-administration the capacity of SSA to suppress morphine and cocaine self-administration in rats and (b) suggest that the GABAB receptor system is likely part of the neural substrate underlying the reducing effect of SSA on alcohol self-administration

Tricyclic pyrazoles. Part 1: synthesis and biological evaluation of novel 1,4-dihydroindeno[1,2-<i>c</i>]pyrazol-based ligands for CB₁ and CB₂ cannabinoid receptors

Cannabinoids receptors, cellular elements of the endocannabinoid system, have been the focus of extensive studies because of their potential functional role in several important physiological and pathological processes. To further evaluate the properties of CB receptors, especially CB1 and CB2 subtypes, we have designed, using SR141716A as a benchmark, a new series of rigid 1-aryl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamides. Compounds 1 were synthesized from substituted 1-aryl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxylic acids and requisite amines. The various analogues were assayed for binding both to the brain and peripheral cannabinoid receptors (CB1 and CB2). Seven of the new compounds displayed very high in vitro CB2 binding affinities, especially 1a, 1b, 1c, 1e, 1g, 1h and 1j which showed Ki values of 0.34, 0.225, 0.27, 0.23, 0.385, 0.037 and 0.9 nM, respectively. Compounds 1a, 1b, 1c and 1h showed the highest selectivity for CB2 receptor with Ki(CB1) to Ki(CB2) ratios of 6029, 5635, 5814 and 9810, respectively. Noticeably, 1h exhibited the highest affinity and selectivity for CB2 receptors