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Title: Obesity-resistant S5B rats showed great cocaine conditioned place preference than the obesity-prone OM rats

Abstract

Dopamine (DA) and the DA D2 receptor (D2R) are involved in the rewarding and conditioned responses to food and drug rewards. Osborne-Mendel (OM) rats are genetically prone and S5B/P rats are genetically resistant to obesity when fed a high-fat diet. We hypothesized that the differential sensitivity of these two rat strains to natural rewards may also be reflected in sensitivity to drugs of abuse. Therefore, we tested whether OM and S5B/P rats showed a differential preference to cocaine using conditioned place preference (CPP). To also evaluate whether there is specific involvement of the D2R in this differential conditioning sensitivity, we then tested whether the D2R agonist bromocriptine (BC) would differentially affect the effects of cocaine in the two strains. OM and S5B/P rats were conditioned with cocaine (5 or 10 mg/kg) in one chamber and saline in another for 8 days. Rats were then tested for cocaine preference. The effects of BC (0.5, 1, 5, 10, 20 mg/kg) on cocaine preference were then assessed in subsequent test sessions. OM rats did not show a significant preference for the cocaine-paired chamber on test day. Only the S5B/P rats showed cocaine CPP. Later treatment with only the highest dose of BC resultedmore » in reduced cocaine CPP in S5B/P rats when treated with 5 mg/kg cocaine and in OM rats treated with 10 mg/kg cocaine. Our results indicated that obesity-resistant S5B rats showed greater cocaine CPP than the obesity-prone OM rats. These findings do not support a theory of common vulnerability for reinforcer preferences (food and cocaine). However, they show that BC reduced cocaine conditioning effects supporting at least a partial regulatory role of D2R in conditioned responses to drugs.« less

Authors:
; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1014346
Report Number(s):
BNL-94741-2011-JA
Journal ID: ISSN 0031-9384; PHBHA4; R&D Project: MO-085; KP1602010; TRN: US201111%%299
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physiology and Behavior; Journal Volume: 101; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; COCAINE; DIET; DOPAMINE; FOOD; METABOLIC DISEASES; SENSITIVITY; STRAINS; VULNERABILITY; Addiction; Psychostimulant; Bromocriptine; Conditioned place preference; PET

Citation Formats

Thanos, P.K., Wang, G., Thanos, P.K.., Kim, R., Cho, J., Michaelides, M., Anderson, B.J., Primeaux, S.D., Bray, G.A., Wang, G.-J., Robinson, J.K., and Volkow, N.D. Obesity-resistant S5B rats showed great cocaine conditioned place preference than the obesity-prone OM rats. United States: N. p., 2010. Web. doi:10.1016/j.physbeh.2010.08.011.
Thanos, P.K., Wang, G., Thanos, P.K.., Kim, R., Cho, J., Michaelides, M., Anderson, B.J., Primeaux, S.D., Bray, G.A., Wang, G.-J., Robinson, J.K., & Volkow, N.D. Obesity-resistant S5B rats showed great cocaine conditioned place preference than the obesity-prone OM rats. United States. doi:10.1016/j.physbeh.2010.08.011.
Thanos, P.K., Wang, G., Thanos, P.K.., Kim, R., Cho, J., Michaelides, M., Anderson, B.J., Primeaux, S.D., Bray, G.A., Wang, G.-J., Robinson, J.K., and Volkow, N.D. 2010. "Obesity-resistant S5B rats showed great cocaine conditioned place preference than the obesity-prone OM rats". United States. doi:10.1016/j.physbeh.2010.08.011.
@article{osti_1014346,
title = {Obesity-resistant S5B rats showed great cocaine conditioned place preference than the obesity-prone OM rats},
author = {Thanos, P.K. and Wang, G. and Thanos, P.K.. and Kim, R. and Cho, J. and Michaelides, M. and Anderson, B.J. and Primeaux, S.D. and Bray, G.A. and Wang, G.-J. and Robinson, J.K. and Volkow, N.D.},
abstractNote = {Dopamine (DA) and the DA D2 receptor (D2R) are involved in the rewarding and conditioned responses to food and drug rewards. Osborne-Mendel (OM) rats are genetically prone and S5B/P rats are genetically resistant to obesity when fed a high-fat diet. We hypothesized that the differential sensitivity of these two rat strains to natural rewards may also be reflected in sensitivity to drugs of abuse. Therefore, we tested whether OM and S5B/P rats showed a differential preference to cocaine using conditioned place preference (CPP). To also evaluate whether there is specific involvement of the D2R in this differential conditioning sensitivity, we then tested whether the D2R agonist bromocriptine (BC) would differentially affect the effects of cocaine in the two strains. OM and S5B/P rats were conditioned with cocaine (5 or 10 mg/kg) in one chamber and saline in another for 8 days. Rats were then tested for cocaine preference. The effects of BC (0.5, 1, 5, 10, 20 mg/kg) on cocaine preference were then assessed in subsequent test sessions. OM rats did not show a significant preference for the cocaine-paired chamber on test day. Only the S5B/P rats showed cocaine CPP. Later treatment with only the highest dose of BC resulted in reduced cocaine CPP in S5B/P rats when treated with 5 mg/kg cocaine and in OM rats treated with 10 mg/kg cocaine. Our results indicated that obesity-resistant S5B rats showed greater cocaine CPP than the obesity-prone OM rats. These findings do not support a theory of common vulnerability for reinforcer preferences (food and cocaine). However, they show that BC reduced cocaine conditioning effects supporting at least a partial regulatory role of D2R in conditioned responses to drugs.},
doi = {10.1016/j.physbeh.2010.08.011},
journal = {Physiology and Behavior},
number = 5,
volume = 101,
place = {United States},
year = 2010,
month =
}
  • Methylphenidate (MP) and amphetamine (AMPH) are the most frequently prescribed medications for the treatment of attention-deficit/hyperactivity disorder (ADHD). Both drugs are believed to derive their therapeutic benefit by virtue of their dopamine (DA)-enhancing effects, yet an explanation for the observation that some patients with ADHD respond well to one medication but not to the other remains elusive. The dopaminergic effects of MP and AMPH are also thought to underlie their reinforcing properties and ultimately their abuse. Polymorphisms in the human gene that codes for the DA D4 receptor (D4R) have been repeatedly associated with ADHD and may correlate with themore » therapeutic as well as the reinforcing effects of responses to these psychostimulant medications. Conditioned place preference (CPP) for MP, AMPH and cocaine were evaluated in wild-type (WT) mice and their genetically engineered littermates, congenic on the C57Bl/6J background, that completely lack D4Rs (knockout or KO). In addition, the locomotor activity in these mice during the conditioning phase of CPP was tested in the CPP chambers. D4 receptor KO and WT mice showed CPP and increased locomotor activity in response to each of the three psychostimulants tested. D4R differentially modulates the CPP responses to MP, AMPH and cocaine. While the D4R genotype affected CPP responses to MP (high dose only) and AMPH (low dose only) it had no effects on cocaine. Inasmuch as CPP is considered an indicator of sensitivity to reinforcing responses to drugs these data suggest a significant but limited role of D4Rs in modulating conditioning responses to MP and AMPH. In the locomotor test, D4 receptor KO mice displayed attenuated increases in AMPH-induced locomotor activity whereas responses to cocaine and MP did not differ. These results suggest distinct mechanisms for D4 receptor modulation of the reinforcing (perhaps via attenuating dopaminergic signalling) and locomotor properties of these stimulant drugs. Thus, individuals with D4 receptor polymorphisms might show enhanced reinforcing responses to MP and AMPH and attenuated locomotor response to AMPH.« less
  • Dopamine (DA) and DAD{sub 2} receptors (D2R) have been implicated in obesity and are thought to be involved in the rewarding properties of food. Osborne-Mendel (OM) rats are susceptible to diet induced obesity (DIO) while S5B/P (S5B) rats are resistant when given a high-fat diet. Here we hypothesized that the two strains would differ in high-fat food self-administration (FSA) and that the D2R agonist bromocriptine (BC) would differently affect their behavior. Ad-libitum fed OM and S5B/P rats were tested in a FSA operant chamber and were trained to lever press for high-fat food pellets under a fixed-ratio (FR1) and amore » progressive ratio (PR) schedule. After sixteen days of PR sessions, rats were treated with three different doses of BC (1, 10 and 20 mg/kg). No significant differences were found between the two strains in the number of active lever presses. BC treatment (10 mg/kg and 20 mg/kg) increased the number of active lever presses (10 mg/kg having the strongest effect) whereas it decreased rat chow intake in the home cage with equivalent effects in both strains. These effects were not observed on the day of BC administration but on the day following its administration. Our results suggest that these two strains have similar motivation for procuring high fat food using this paradigm. BC increased operant responding for high-fat pellets but decreased chow intake in both strains, suggesting that D2R stimulation may have enhanced the motivational drive to procure the fatty food while correspondingly decreasing the intake of regular food. These findings suggest that susceptibility to dietary obesity (prior to the onset of obesity) may not affect operant motivation for a palatable high fat food and that differential susceptibility to obesity may be related to differential sensitivity to D2R stimulation.« less
  • Acetone is a component in many inhalants that have been widely abused. While other solvents have addictive potential, such as toluene, it is unclear whether acetone alone contains addictive properties. The locomotor, relative glucose metabolism and abusive effects of acetone inhalation were studied in animals using the conditioned place preference (CPP) paradigm and [18F]2-fluorodeoxy-D-glucose (18FDG) imaging. The CPP apparatus contains two distinct conditioning chambers and a middle adaptation chamber, each lined with photocells to monitor locomotor activity. Adolescent Sprague-Dawley rats (n=16; 90-110 g) were paired with acetone in least preferred conditioning chamber, determined on the pretest day. The animals weremore » exposed to a 10,000 ppm dose for an hour, alternating days with air. A CPP test was conducted after the 3rd, 6th and 12th pairing. In these same animals, the relative glucose metabolism effects were determined using positron emission tomography (PET) imaging with 18FDG. Following the 3rd pairing, there was a significant aversion to the acetone paired chamber (190.9 ± 13.7 sec and 241.7 ± 16.9 sec, acetone and air, respectively). After the 6th pairing, there was no significant preference observed with equal time spent in each chamber (222 ± 21 sec and 207 ± 20 sec, acetone and air-paired, respectively). A similar trend was observed after the 12th pairing (213 ± 21 sec and 221 ± 22 sec, acetone and air-paired, respectively). Locomotor analysis indicated a significant decrease (p<0.05) from air pairings to acetone pairings on the first and sixth pairings. The observed locomotor activity was characteristic of central nervous system (CNS) depressants, without showing clear abusive effects in this CPP model. In these studies, acetone vapors were not as reinforcing as other solvents, shown by overall lack of preference for the acetone paired side of the chamber. PET imaging indicated a regionally specific distribution of 18FDG uptake following acetone exposure. Further studies using different concentrations are required to better understand the locomotor and behavioral effects of acetone. This study confirms that the combination of microPET and the CPP paradigm can be used to elucidate the effects of abused solvents vs. non-abused solvents in inhalants.« less
  • Deficits in dopamine D2/D3 receptor (D2R/D3R) binding availability using PET imaging have been reported in obese humans and rodents. Similar deficits have been reported in cocaine-addicts and cocaine-exposed primates. We found that D2R/D3R binding availability negatively correlated with measures of body weight at the time of scan (ventral striatum), at 1 (ventral striatum) and 2 months (dorsal and ventral striatum) post scan in rats. Cocaine preference was negatively correlated with D2R/D3R binding availability 2 months (ventral striatum) post scan. Our findings suggest that inherent deficits in striatal D2R/D3R signaling are related to obesity and drug addiction susceptibility and that ventralmore » and dorsal striatum serve dissociable roles in maintaining weight gain and cocaine preference. Measuring D2R/D3R binding availability provides a way for assessing susceptibility to weight gain and cocaine abuse in rodents and given the translational nature of PET imaging, potentially primates and humans.« less
  • Both copper (Cu) nutriture and cocaine (Coc) ingestion have been shown to affect cardiovascular integrity. Therefore, the purpose of these studies was to determine if Cu status affects the acute toxicity of Coc. 20 weanling male rats (45 {plus minus} 5 g) were randomly assigned to 2 groups, 1 fed a copper deficient (CuD) (<1ppmCu) and the other a copper supplemented (CuS) diet (ca.6ppm, Cu). After 7 wks, the rats, paired for Cu status, were injected (ip) with Coc-HCl at reported LD{sub 50} doses ranging from 80-90 mg/kg bw. The CuD was established by cardiac hypertrophy, depressed hematocrit, lowered serum,more » liver and heart Cu compared to the CuS controls. The acute toxicity resulted in tachycardia and hyperactivity followed by ataxia with isolated muscle twitchings and violent grand-mal type seizures. For those animals that died, death was apparently due to respiratory arrest followed by ventricular fibrillation; animals that survived were killed by exsanguination. The severity of toxicity was greater for the CuD rats as evidenced by 100% exhibiting seizures compared to 80% for the CuS group. In addition, the incidence of death was 60% for the CuD group compared to 20% for the CuS rats. Although these results suggest that CuD exacerbates the toxic effects of Coc, it is not established that the effects are specific for this essential nutrient.« less