Tone conditioning potentiates rather than overshadows context fear in adult animals following adolescent ethanol exposure

Abstract

We have shown that adults exposed to ethanol during adolescence exhibit a deficit in the retention of context fear, reminiscent of that normally seen in preweanling rats. However, preweanlings have been reported to exhibit a potentiation of context fear when they are conditioned in the presence of a tone. Therefore, this study examined context retention 24 hr after tone or context conditioning in male Sprague-Dawley rats exposed intragastrically to 4 g/kg ethanol or water every 48 hr (total of 11 exposures) during adolescence [Postnatal day (P) 28-48] or adulthood (P70-90). Approximately 3 weeks following exposure, retention of fear to the context in animals exposed to ethanol during adolescence was attenuated after context conditioning, but enhanced after tone conditioning. Comparable adult ethanol exposure groups showed typical overshadowing of context fear retention after tone conditioning. These data suggest that adolescent ethanol exposure may induce an immature pattern of cognitive processing.

Effects of ethanol exposure during adolescence or in adulthood on Pavlovian conditioned approach in Sprague-Dawley rats

“…2), ethanol- and water-treated animals were weighed and given their assigned exposure of either 4 g/kg (25% v/v) ethanol, or an equivalent volume of water intragastrically between 1100 and 1300 h every other day for a total of 11 intubations. This dose has been found to produce initial intoxication ratings in the slight (adolescents) to moderate (adult rats) range (Broadwater & Spear, 2013) and peak blood ethanol levels (BECs) of approximately 200 mg/dL (unpublished observations). Although above the threshold for binge drinking (i.e., > 80 mg/dL), these ethanol levels are well within the range of those reported in underage drinkers and in young drinkers of legal age in recent field studies (Day, Celio, Lisman, Johansen, & Spear, 2013).…”

“…For example, cognitive deficits (Coleman, He, Lee, Styner, & Crews, 2011; Pascual, Blanco, Cauli, Miñarro, & Guerri, 2007) and increased alcohol intake under certain circumstances (Broadwater & Spear, 2013; Matthews, Tinsley, Diaz-Granados, Tokunaga, & Silvers, 2008) have been seen in adulthood after AIE. Yet, the data are mixed with, for instance, reports of increased ethanol consumption, contrasting with other findings of decreased ethanol consumption in adulthood after AIE (Gilpin, Karanikas, & Richardson, 2012).…”

Adolescent alcohol exposure and persistence of adolescent-typical phenotypes into adulthood: A mini-review

“…Immature animals, in contrast, show the opposite, displaying potentiation of context conditioning when footshock is paired with a tone CS+ in that context during conditioning. After AIE, adults exhibited this immature potentiation effect, a consequence specific to ethanol exposure during adolescence, with adults showing the normal, adult-typical pattern of overshadowing when tested at the same period of time after CIE (Broadwater & Spear, 2014a). Clearly, more work is needed to determine the relative pervasiveness of AIE-associated retention of adolescent-typical baseline behavior and cognitive function into adulthood beyond the limited findings reported to date.…”

“…For instance, adolescent-like phenotypes have emerged after intragastric (ig) AIE exposure regimens of every other day administration of 3.5 or 4 g/kg ethanol in Sprague-Dawley rats (e.g., Broadwater & Spear, 2013a, b e.g., Broadwater & Spear, 2014a, b; Varlinskaya et al, 2014) as well as a two day on, two day off, exposure regimen to 5 g/kg ethanol in Sprague-Dawley rats (e.g., Fleming et al, 2007, 2012, 2013). Persistence of adolescent typical phenotypes have also been reported after AIE using every other day intraperitoneal injections of 3.0 g/kg ethanol in Sprague-Dawley rats (e.g., Alaux-Cantin et al, 2013) as well as when using intermittent (14 hrs.…”

Oxytocin and vasopressin modulation of social anxiety following adolescent intermittent ethanol exposure

“…during adolescence producing average peak blood ethanol concentrations (BECs) in the range of 130–200 mg/dL (see Kim et al, in press), similar to those estimated for binge drinking in early adolescents (Donovan, 2009). Adolescent exposure to ethanol in this range in rats has been shown to induce long-lasting behavioral and neural alterations that are not evident in controls receiving water i.g (Broadwater & Spear, 2014; Liu & Crews, 2017; Vetreno et al, 2017; Risher et al, 2015a,b; Swartzwelder et al, 2017). For instance, we have shown long-lasting and sex-dependent detrimental consequences of repeated intermittent i.g.…”