Comparison of Alcohol‐Preferring and Nonpreferring Selectively Bred Rat Lines. II. Operant Self‐Administration in a Continuous‐Access Situation

Abstract

Several rat lines have been developed using preference/nonpreference and daily ethanol intake in the homecage as criteria for selective breeding. Using these lines, behavioral and neural factors that may underlie the genetic basis for the control of ethanol consumption have been examined. In this paper, we report data from eight of these selected lines: the Alcohol-Preferring (P) and Alcohol-Nonpreferring (NP), the Alcohol-Accepting (AA) and Alcohol-Nonaccepting (ANA), and the High Alcohol Drinking (HAD1 and HAD2) and Low Alcohol Drinking (LAD1 and LAD2) rats. All lines were tested using operant procedures and the same protocols for both the ethanol self-administration initiation and measurement of continuous-access ethanol consumption. During continuous access, the animals were housed in operant chambers with access to 10% (v/v) ethanol after responses on one lever, food pellets (45 mg) after responses on a second lever, and water in a drinking tube that was connected to a drinkometer circuit. Under these procedures, both similarities and differences among the selected lines on continuous-access operant ethanol intake were observed. For example, overall total homecage ethanol drinking was similar for the AA and both HAD lines. When examined in the operant continuous-access situation, however, the AA rats displayed a different consumption pattem, compared with the HAD lines. Data suggest that the frequency of drinking bouts was a primary factor in the phenotypic homecage selection of the preferring lines that was revealed by the use of the continuous-access operant procedure. In general, data suggest that genes related to ethanol preference and intake in homecage continuous-access situations may not be identical to those related to ethanol's reinforcing function in operant continuous-access conditions. Because ethanol consumption appears to be controlled by different drinking patterns across lines, the selected lines provide for a variety of models to understand how varying genotypes can impact ethanol consumption.

Excessive Ethanol Drinking Following a History of Dependence Animal Model of Allostasis

“…Thus, the alcohol deprivation effect does not appear to be changed in any qualitative manner following dependence, but rather an overall increase in ethanol selfadministration has occurred. The level of ethanol selfadministration observed during protracted abstinence in this population of genetically heterogeneous rats is similar to that observed under similar conditions, but with no deprivation periods, in rats genetically selected for preference for alcohol (Li and McBride 1995;Files et al 1998;Samson et al 1998).…”

A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction

“…P rats operantly self-administer ethanol intragastrically for its post-ingestive effects (Murphy et al, 1988; Waller, McBride, Gatto, Lumeng, & Li, 1984). P rats will operantly self-administer ethanol using a dipper model, indicating these rats will work for access to ethanol (Files, Samson, Denning, & Marvin, 1998; Murphy, Gatto, McBride, Lumeng, & Li, 1989; Rodd et al, 2003; Rodd-Henricks et al, 2002a, 2002b; Samson, Files, Denning, & Marvin, 1998; Toalston et al, 2008) or sipper tube model (Beckwith & Czachowski, 2014; Bertholomey, Verplaetse, & Czachowski, 2013; Czachowski & Samson, 2002; Samson & Czachowski, 2003; Verplaetse, Rasmussen, Froehlich, & Czachowski, 2012; Verplaetse & Czachowski, 2015) indicating these rats will work for access to ethanol.…”

“…Ethanol is operantly self-administered, without using fading/adaptation techniques (i.e., P rats work for access to ethanol) (Files et al, 1998; Murphy et al, 1989; Rodd et al, 2003; Rodd-Henricks et al, 2002a, 2002b; Rodd-Henricks, McKinzie, Shaikh, et al, 2000; Samson et al, 1998; Toalston et al, 2008)…”

The alcohol-preferring (P) and high-alcohol-drinking (HAD) rats – Animal models of alcoholism

“…Also, the animals should be willing to work to obtain the alcohol. Several studies demonstrated that P rats will operant respond even with high workload (fixed-ratio) requirements (Ciccicioppo, Angeletti, & Weiss, 2001; Czachowski & Samson, 2002; Files, Samson, Denning, & Marvin, 1998; Murphy, Gatto, McBride, Lumeng, & Li, 1989; Rodd et al, 2003; Samson, Files, Denning, & Marvin, 1998), achieving estimated BACs in excess of 80 mg% (Rodd et al, 2003). Moreover, recently it has been demonstrated that P rats will exhibit ‘loss-of-control’ binge-like alcohol drinking and attain BACs of 200 mg% on a daily basis (McBride et al, 2013).…”