Benzodiazepines reduce the tolerance to reward delay in rats

Abstract

This study investigated whether benzodiazepines reduce the capacity of animals to wait for food reward. Rats trained in a T-maze were allowed to choose between two magnitudes of reward: immediate, but small (two pellets) vs delayed, but large (eight pellets). The rats learned within ten sessions to select (80-100%) the arm leading to the largest reward. Separate groups of rats were then confined for 15, 30 or 60 s in the arm associated with the largest reward before gaining access to the spacially contiguous goal-box. The choice of the other arm was not followed by a period of waiting. Under these conditions, the frequency with which the small-reward arm was chosen increased linearly as a function of the duration of the waiting period. Diazepam (2-4 mg/kg IP) dose-dependently increased the number of times the small-reward arm was chosen during the sessions for which the waiting period was fixed at 15 or 30 s. Nitrazepam (2 mg/kg IP), chlordiazepoxide (16 mg/kg IP) and clobazam (16 mg/kg IP) had similar effects. The action of diazepam was counteracted by simultaneous administration of flumazepil (Ro 15-1788, 8 mg/kg PO). In the absence of confinement, these benzodiazepines, diazepam (4 mg/kg) excepted, did not modify selection of the large-reward arm. Conversely, the serotonin uptake blockers indalpine (2-4 mg/kg IP) and zimelidine (8-16 mg/kg IP) dose-dependently increased preference for the arm leading to the delayed (25 s) but large reward. These results suggest that benzodiazepines, perhaps by increasing impulsivity, render the animals less prone than controls to tolerate delayed access to reward.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective Serotonin Reuptake Inhibitors Decrease Impulsive Behavior as Measured by an Adjusting Delay Procedure in the Pigeon

“…This decrease was maintained over a period of five days of drug administration but promptly returned to the predrug control values upon cessation of alprazolam administration. These data are consistent with the suggestion that benzodiazepines increase impulsive behavior by dampening the serotonergic system (Thiebot et al 1985). Benzodiazepines reportedly decrease 5-HT turnover (Saner and Pletscher 1979), decrease the firing rate of 5-HT neurons (Trulson et al 1982), and reduce the amount of 5-HT released from nerve endings (Soubrie et al 1983).…”

“…Benzodiazepines have been reported to decrease tolerance of reward delay in rats (Thiebot et al 1985) although some discrepancies have been reported with respect to alprazolam (Bizot et al 1999). Furthermore, chronic benzodiazepine use increased aggressive, violent, and impulsive behavior in some patients (Mathew et al 2000;Gardner and Cowdry 1985).…”

“…In other operant paradigms that were designed to study the ability of an animal to wait for reinforcement (Evenden and Ryan 1996;Charrier and Thiebot 1996), acute administration of SSRIs was also ineffective. However in the T-maze, acute administration of SSRIs was sufficient to increase the number of choices of a large delayed reward (Bizot et al 1988;Thiebot et al 1985).…”

“…Neuropharmacological manipulations that affect the concentration of 5-HT in the brain modify the effec-tiveness of a reward when its delivery is delayed (Soubrie 1986). For example, administration of 5-HT reuptake inhibitors increased responding for a delayed reward (Thiebot et al 1985), whereas lesions of the 5-HT system decreased the willingness of rats to respond for a delayed reward (Wogar et al 1993).…”

Sexual Impulsivity in Hypersexual Men

“…It seems unlikely that such disparate behaviors reflect a unitary underlying behavioral process; however, deficits in behavioral inhibition [34], waiting capacity [35], timing [36,37], behavioral switching [38], and tolerance of delay of gratification [33,39] have been proposed to encompass many of these behavioral phenomena [40]. Further, given the diversity of behaviors most often characterized by impulsivity (e.g., violence, gambling, spending sprees, substance abuse, hypersexual behavior, and self-injurious behavior), it seems it cannot be best understood as a product of a single appetitive or a particular consumed substance.…”