Oral Self-Administration of Ethanol and Cocaine in Rats

Abstract

Most laboratory animal studies on self-administration of drugs of abuse use only one drug, whereas humans frequently engage in polydrug use. For this reason, we studied oral self-administration of ethanol (E) and cocaine (C) with the free choice bottle method using a single drug alone, a combination (E and C in separate bottles) or a mixture of both drugs in a single bottle. Young female rats (45 days) consumed similar amounts of C if offered alone (12.4 ± 7.5 mg/kg/day), in the presence of ethanol (10.6 ± 3.5) or as E/C mixture (8.0 ± 4.0). They also consumed similar amounts of E if offered alone (3.8 ± 1.6 ml/kg/day), in the presence of C (2.3 ± 0.8) or E/C mixture (2.4 ± 1.1). Voluntary consumption of both drugs varied markedly among animals but was consistent in a given rat. No correlation occurred between consumption of E and C. Young male rats behaved similarly and consumed similar amounts of E and C alone, in combination and as mixture. While E consumption was similar, C consumption was higher in female rats. Old male rats (180 days) were similar to young male rats. The presence of a saccharin solution as a distracter had no effect on intake of E or C in young females but reduced E intake only in young male rats. In young animals, prior voluntary consumption of either E or C had no effect on subsequent voluntary consumption of the same or other drug offered in combination. These results indicate that this model may be useful to study polydrug use in humans, that consumption of both E and C is strongly controlled by an individual animal, that prior exposure to one drug had no or little effect on a subsequent consumption of the same or other drug in combination and that intake of E or C seems to be independent of each other suggesting two independent reward centers.

Voluntary Self-Administration of Both Morphine and Cocaine by Rats

“…In contrast, we found that self-administration of ethanol and cocaine (in combination) did not affect each other [21]. Rats consumed the same amounts of either ethanol or cocaine whether these drugs were offered separately, together in 2 bottles or as a mixture.…”

Factors associated with the transition from abuse to dependence among substance abusers: Implications for a measure of addictive liability

“…One hypothesis was that LOTAD will be shorter for persons who initiate use of a drug at a young age than other users (Brook et al, 2002;DeWitt et al, 2000). A second hypothesis was based on the finding that, among animals primed for selfadministration of an addictive substance, females consume greater volumes of the substance than males (Cicero et al, 2000;Grathwohl et al, 2001). Hence, it was hypothesized that LOTAD will be shorter in women than men.…”

Cocaína prenatal y consumo de cocaína de ratones adultos jóvenes

“…Esta mayor fortaleza de las hembras a la exposición in útero a la cocaína se ha encontrado reiteradamente en diferentes estudios (Dow-Edwards et al, 2014;Grathwohl, Dadmarz, & Vogel, 2001;Hu, Crombag, Robinson, & Becker, 2004;Lynch, Roth, Mickelberg, & Carroll, 2001;Malanga et al, 2008;Peña-Oliver, 2007;Rocha, 2005;Rocha et al, 2002).…”

“…Esta situación puede obedecer a la diferenciación sexual del cerebro sumado a la relación con el estro; ya que cuando las hembras de rata/ratón están en su ciclo estral, adquieren la autoadministración más rápidamente y presentan mayor búsqueda de drogas (Grathwohl, Dadmarz, & Vogel, 2001;Hu, Crombag, Robinson, & Becker, 2004;Lynch et al, 2001). …”

“…O, que la naltrexona (antagonista opiáceo/opioide) reduce el consumo de alcohol, no de cocaína (Stromberg et al, 2002). Y que los ratones machos son poliadictos (consumieron alcohol y cocaína) a diferencia de las hembras que consumieron únicamente cocaína, aunque en mayor cantidad que los machos (Grathwohl, Dadmarz, & Vogel, 2001). …”