Effects of Strain, Behavior and Age on the Self-Administration of Ethanol, Nicotine, Cocaine and Morphine by Two Rat Strains

Abstract

Two genetically different strains, Brown Norway rats (BNR) and Wistar Kyoto rats (WKR), with the latter showing higher emotionality and lower plasma stress catecholamine responses, were compared for their voluntary intake of ethanol, nicotine, cocaine and morphine. Younger BNR self-administered the same amounts of all 4 substances as did the younger WKR suggesting a similar genetic basis for all drugs at this age. Older BNR consumed less ethanol and nicotine but equal amounts of cocaine and morphine as compared to older WKR, and older BNR were more sensitive to the effects of ethanol than WKR suggesting a different genetic basis for different drugs at an older age. Forcing both strains to consume one of the drugs did not affect a subsequent voluntary consumption of ethanol and morphine but reduced nicotine intake in WKR and decreased cocaine intake in both strains suggesting that drug use is determined by individual preferences and not drug exposure per se. The behavioral characteristics of both strains coincide only with the self-administration of ethanol and nicotine supporting a possible genetic linkage between anxiety/stress and ethanol and nicotine use.

Self-Administration of both Ethanol and Nicotine in Rats

“…This study more closely resembles the situation in humans who may use both drugs at the same time. This two-or three-bottle freechoice method has been used widely for ethanol, but has now been shown to be also valid for nicotine and other drugs as well [e.g., 5,8,9,[26][27][28][29].…”

Nicotine addiction: insights from recent animal studies

“…They also examined age as an important mediating 107 variable. Both strain and age differences were found, with the WKR consuming more ethanol and nicotine than the BNR, and the older BNR consumed less nicotine and ethanol than the younger (Todte et al 2001). These and other Stolerman et al 1999) recent studies therefore support future investigation of the influence of genetic factors in nicotine SA.…”

“…Lastly, in an attempt to look at the interplay between genetics and the SA of drugs of abuse, Todte et al (2001) examined the propensity of Brown-Norway rats (BNR) and Wistar-Kyoto rats (WKR) to orally self-administer ethanol, nicotine, cocaine, and morphine. The WKR strain is known for its higher emotionality and its lower plasma stress catecholamine responses (Todte et al 2001).…”

“…The WKR strain is known for its higher emotionality and its lower plasma stress catecholamine responses (Todte et al 2001). They also examined age as an important mediating 107 variable.…”

Sex differences in response to nicotine in C57Bl/6:129SvEv mice

“…Two-bottle choice has been reported to demonstrate both aversion and preference for nicotine in mice depending on nicotine concentration ( Adriani, Macri, Pacifi ci, & Laviola, 2002 ;Agatsuma et al, 2006 ;Klein, Stine, Pfaff, & Vandenbergh, 2003 ;Klein, Stine, Vandenbergh, Whetzel, & Kamens, 2004 ;Lee, Chen, Shih, & Hiroi, 2004 ;Meliska, Bartke, McGlacken, & Jensen, 1995 ;Robinson, Marks, & Collins, 1996 ;Zhu et al, 2005 ). In a twobottle choice paradigm, mice are exposed to two bottles: one containing water and the other nicotine, the locations of which are switched every few days to prevent conditioned place associations from masking drug effects ( Klein, 2001 ;Klein et al, 2004 ;Shaham, Alvares, Nespor, & Grunberg, 1992 ;Todte et al, 2001 ).…”