Alcohol administration blocks stress-induced impairments in memory and anxiety, and alters hippocampal neurotransmitter receptor expression in male rats

Abstract

Chronic exposure to stress has many deleterious effects on behavior, which can often lead to self-medication with anxiolytics, antidepressants, or alcohol. We determined the effects of alcohol administration following a stressor on established behavioral, physiological, and neural responses to stress. Male Sprague-Dawley rats received: No alcohol / No stress (CON), Alcohol alone (ALC), Stress alone (STR), or Stress plus Alcohol (STR+ALC). For seven consecutive days, two cohorts received an oral dose of 2 g/kg of either 20% ethanol or saline. In Cohort 1, behavioral testing began after the final treatment (day-8). Memory was tested using the object recognition (OR) and Y-maze, anxiety on the plus maze, and depression on the forced swim task. Memory on OR and Y-maze tasks was impaired in the ALC and STR groups. This deficit was reversed in the STR+ALC group, which performed not differently from the CON group. Stress alone was associated with increased anxiety, which was alleviated with alcohol treatment. No treatment effects were found in the forced swim task. In Cohort 2, hippocampal GABAα4 was upregulated in the STR+ALC group and GluN2B was upregulated in the ALC and STR+ALC groups. The STR+ALC group in Cohort 1 showed enhanced corticosterone levels after forced swim. The STR+ALC group in Cohort 2 showed increased corticosterone levels on day-1 of treatment and a habituation by day-7. In conclusion, this study found a reversal of stress-induced deficits in cognition and anxiety when alcohol was given post-stress, and changes in neurotransmitter receptor expression may contribute to these behavioral effects.

The effects of gonadectomy and binge-like ethanol exposure during adolescence on open field behaviour in adult male rats

“…In the present study, chronic intake resulted in increases in depression, and the effects were often greater in females than in males [30]. Another study found that chronic alcohol increased depressive-like behaviours in females,which was an effect not observed in males [31]. Consistent with the experimental results, alcohol treatment increased immobility, a sign of depressive-like behaviour, in the GX-eth rats.…”

Sex differences in chronic stress effects on cognition in rodents

“…For object placement, one week of restraint stress did not affect memory in males while 3 weeks impaired memory (Beck and Luine, 2002; Gomez et al, 2012). In object recognition, either one or three weeks of stress impaired male memory (Beck and Luine, 1999; 2002; Gomez et al, 2013). Overall, the time course of stress effects on male cognition is consistent with the conclusions of Selye (1976) and others who showed that short-term stress elicits adaptive physiological responses but that continued stress exposure results in maladaptive responses.…”

“…In tests assessing spatial memory (not learning), chronic stress also generally impairs male performance (See Conrad, 2010 for review). Spatial memory in both the object placement (Beck and Luine, 1999; Bowman et al, 2009; Gomez et al, 2012; Beck and Luine, 2002) and the Y-maze task is impaired following 3 weeks of daily restraint (Conrad et al, 2003; Wright and Conrad, 2005; Gomez et al, 2013). As shown for the object placement task (left two bars of Fig.…”

Estradiol: Mediator of memories, spine density and cognitive resilience to stress in female rodents

“…Stressed male rats and mice are unable to significantly discriminate between known and new objects in the NOR test [41, 42] or on a test of temporal order recognition memory (TORM) [43 and Figure 5A]. Spatial memory in males is also impaired by chronic stress in NOP (Figure 4B) [41, 44, 45] and the Y-maze [46, 47, 48]. Thus, chronic stress impairs learning and memory in male rodents in a variety of tasks.…”