Sensitivity and Tolerance to Autonomic Effects of Ethanol in Adolescent and Adult Rats During Repeated Vapor Inhalation Sessions

Abstract

In contrast to results indicating that adolescents may be less sensitive than adults to ethanol's hypothermic effect when ethanol is administered via bolus injection/intubation, adolescents appear more sensitive and develop tolerance to ethanol's hypothermic effects more slowly than adults when ethanol is administered at a more moderate rate via vapor inhalation.

Chronic tolerance to the social consequences of ethanol in adolescent and adult Sprague-Dawley rats

“…Together, these results raise the possibility that greater amount of experimental perturbation/stress may foster greater expression of chronic tolerance in adolescents, whereas chronic tolerance may emerge similarly across age under less perturbing exposure/test circumstances. With a minimally invasive route of ethanol administration via vapor inhalation and indwelling telemetry probes for temperature recording, adolescents showed even less chronic tolerance to the hypothermic effects of ethanol than adults [25]. This finding is consistent with the postulation that age-related differences in ethanol adaptations (or the lack thereof) may be related, at least in part, to the degree of experimental perturbation/ stress involved.…”

“…To the extent that these data are applicable to humans, the results of the present study along with other research employing animal models of adolescence [e.g., 5,12,25,29,30,34,45,46] provide further evidence that adolescents may respond and adapt differently to repeated episodes of ethanol exposure than their more mature counterparts, with mechanisms underlying these adaptations also being age-specific. In addition to further characterizing adolescentspecific neurobehavioral alterations following repeated ethanol exposure, studies are needed to explore whether these adolescent-specific adaptations to and consequences of chronic ethanol might put them at higher risk for extensive alcohol use and the eventual emergence of alcohol abuse disorders.…”

“…Chronic exposure to high doses of ethanol (4 g/kg twice a day for 7 days) administered intragastrically was reported to induce more tolerance in adolescent than adult rats when indexed in terms of ethanol-induced hypothermia and sedation [34]. However, when animals were chronically exposed to ethanol via vapor inhalation, tolerance to hypothermic effects of ethanol was found to develop faster in adult rats than in their younger counterparts [25]. In a study equating initial functional motor impairment across age by dose adjustments, equivalent levels of tolerance were observed across the two ages [28].…”

Decreased sensitivity in adolescent vs. adult rats to the locomotor activating effects of toluene

“…Finally, adolescent animals have also been found to be differentially sensitive to the acute effects of other CNS depressants that do not share the same pharmacokinetic mechanisms as toluene. Indeed, previous studies have shown that the degree to which a specific drug will affect adolescents differently than adults may be affected by multiple factors, including the specific behavior measured [55], the exact age of the animal [59], and the route of administration [43]. For example, adolescent rodents are less sensitive to ethanol-induced motor disruption and loss of righting reflex than are adult rodents [23,33].…”

Ontogeny of Acute Tolerance to Ethanol‐Induced Social Inhibition in Sprague–Dawley Rats

“…On the other hand, when compared with their adult counterparts, adolescent rats are less sensitive to a variety of acute effects of ethanol, including ethanol-induced motor impairment (Hollstedt et al, 1980;Spear, 1998,2001;White et al, 2002), sedation (Little et al, 1996;Moy et al, 1998), and anxiolysis (Varlinskaya and Spear, 2002). Sensitivity to hypothermic effects of ethanol has been also reported to increase across ontogeny (Silveri and Spear, 2000), although findings with this measure are more mixed (Brasser and Spear, 2002;Ristuccia and Spear, 2005;Swartzwelder et al, 1998) and may be related to the amount of perturbation of the test circumstances (Ristuccia and Spear, under revision).…”