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

Abstract

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 [(3)H]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.

Keywords: GET73; Sardinian alcohol-preferring rats; alcohol deprivation effect; alcohol intake; anxiety-related behaviors; γ-hydroxybutyric acid.

Figure 1

Molecular structure of GHB and GET73.

Figure 2

The water maze apparatus and its different zones, coded as follows: (A) entry zone; (A–E) blind alleys (error zones); (F) exit zone.

Figure 3

Effect of the acute, intragastric administration of different doses of GET73 on spontaneous locomotor activity in Sprague-Dawley rats. GET73 was administered 30 min before the start of the 30-min session. Data were recorded in six 5-min bins; total distance traveled over the 30-min session is reported in the inset. Each point or bar is the mean ± SEM of n = 8. *P < 0.05 with respect to 0-mg/kg GET73-treated rat group at the corresponding time (Newman–Keuls test).

Figure 4

Effect of the repeated, intraperitoneal administration of different doses of GET73 on three measures of spatial memory in Sprague-Dawley rats exposed to the water maze (WM) test: number of alley errors [entries into blind alleys (A)], number of swimming reversals [defined as complete U-turns (B)], number of working-memory errors [re-entries in blind alleys already visited in the on-going session (C)], and distance traveled [in cm; (D)]. GET73 was administered 30 min before each WM session. Each WM session lasted for 5 min. Each point is the mean ± SEM of n = 10. *P < 0.05, **P < 0.01, and ***P < 0.001 with respect to 0-mg/kg GET73-treated rat group in the corresponding session (Kruskal–Wallis and Mann–Whitney test).

Figure 5

Effect of the acute, intragastric administration of different doses of GET73 on two measures of “anxiety” [number of entries into open arms (OAs; %EOAs; expressed as percent of total number of entries into arms (A))]; time spent in OAs [(%TOAs; expressed as percent of total time spent in arms (B)] in Sprague-Dawley rats exposed to the elevated plus maze (EPM) test. GET73 was administered 30 min before the EPM test. Exposure to the EPM lasted for 5 min. Entry into a given arm was scored once the rat had all four paws in that arm. Each bar is the mean ± SEM of n = 4–7. *P < 0.05 and **P < 0.01 with respect to 0-mg/kg GET73-treated rat group (Kruskal–Wallis and Mann–Whitney test).

Figure 6

Effect of the acute, intragastric administration of different doses of GET73 on two measures of “anxiety” [number of entries into open arms (OAs; %EOAs; expressed as percent of total number of entries into arms (A))]; time spent in OAs [(%TOAs; expressed as percent of total time spent in arms (B)] in Sardinian alcohol-preferring (sP) rats exposed to the elevated plus maze (EPM) test. GET73 was administered 30 min before the EPM test. Exposure to the EPM lasted for 5 min. Entry into a given arm was scored once the rat had all four paws in that arm. Each bar is the mean ± SEM of n = 12–14. *P < 0.05 and **P < 0.01 with respect to 0-mg/kg GET73-treated rat group (Newman–Keuls test).

Figure 7

Effect of the acute, intragastric administration of different doses of GET73 on alcohol (A–D), water (E–H), and food (I–L) intake in “alcohol-experienced” Sardinian alcohol-preferring (sP) rats. Alcohol (10% v/v, in water) was offered under the standard, homecage two-bottle “alcohol vs water” choice regimen with unlimited access for 24 h/day. GET73 was administered 30 min before lights off. Alcohol, water, and food intake was recorded 60, 120, 180, and 240 min after lights off. Each bar is the mean ± SEM of n = 10 rats. *P < 0.05, **P < 0.01, and ***P < 0.005 with respect to 0-mg/kg GET73-treated rat group (Newman–Keuls test).

Figure 8

Effect of the acute, intragastric administration of low (A), moderate (B), and high doses (C) of GET73 – tested in three independent experiments – on the “alcohol deprivation effect” (ADE) in Sardinian alcohol-preferring (sP) rats. Alcohol (10% v/v, in water) was offered under the standard, homecage two-bottle “alcohol vs water” choice regimen with unlimited access for 24 h/day. Alcohol-deprived rats were deprived of alcohol for 14 consecutive days; alcohol-non-deprived rats had continuous access to alcohol and water. Thirty minutes before representation of the alcohol bottle (which coincided with lights off), both alcohol-deprived and -non-deprived rats were treated acutely with GET73. Alcohol intake was registered 60 min after lights off. Each bar is the mean ± SEM of n = 7–18. *P < 0.05 with respect to alcohol-non-deprived rats receiving 0 mg/kg GET73 (Newman–Keuls test); ^+P< 0.05 with respect to alcohol-deprived rats receiving 0 mg/kg GET73 (Newman–Keuls test).