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Andrade AK, Renda B, Sharivker M, Lambert K, Murray JE. Sex differences in the discriminative stimulus characteristics of a morphine occasion setter in rats. Pharmacol Biochem Behav 2021; 205:173173. [PMID: 33753118 DOI: 10.1016/j.pbb.2021.173173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/19/2021] [Accepted: 03/15/2021] [Indexed: 10/21/2022]
Abstract
The current study investigated whether the stimulus effects of morphine can function as a positive and negative feature in a Pavlovian occasion setting drug discrimination preparation in male and female rats. Sprague-Dawley rats were assigned to a feature positive (FP) or feature negative (FN) training group and all received intermixed morphine (3.2 mg/kg, IP) or saline injections 15 min before 20-min daily training sessions. For FP rats, on morphine sessions, each of eight 15-s white noise (WN) presentations was followed by 4-s access to sucrose (0.01 ml, 26% w/v); on saline sessions, sucrose was withheld. FN rats learned the reverse contingency. FP discrimination was acquired somewhat sooner than FN discrimination, and females, but not males, became sensitized to the locomotor effects of morphine, which did not influence conditioned responding. Rats then entered dose generalization testing. There was no sex difference in dose generalization for FN groups (ED50 1.26 for males and 1.57 for females). Yet for FP rats, the dose response curve for females was shifted to the right compared to males (ED50 0.54 for males and 1.94 for females). FP females exhibited enhanced responding at a dose higher than that of their original training. These findings reveal the need to reassess our notions of drug stimuli that guide appropriate associative behaviours from the perspective of sex differences.
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Affiliation(s)
- Allyson K Andrade
- Department of Psychology, University of Guelph, Guelph, ON, Canada; Collaborative Neurosciences Graduate Program, University of Guelph, Guelph, ON, Canada
| | - Briana Renda
- Department of Psychology, University of Guelph, Guelph, ON, Canada; Collaborative Neurosciences Graduate Program, University of Guelph, Guelph, ON, Canada
| | - Michael Sharivker
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Karlie Lambert
- Department of Psychology, University of Guelph, Guelph, ON, Canada
| | - Jennifer E Murray
- Department of Psychology, University of Guelph, Guelph, ON, Canada; Collaborative Neurosciences Graduate Program, University of Guelph, Guelph, ON, Canada.
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Mavanji V, Perez-Leighton CE, Kotz CM, Billington CJ, Parthasarathy S, Sinton CM, Teske JA. Promotion of Wakefulness and Energy Expenditure by Orexin-A in the Ventrolateral Preoptic Area. Sleep 2015; 38:1361-70. [PMID: 25845696 DOI: 10.5665/sleep.4970] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/07/2015] [Indexed: 12/25/2022] Open
Abstract
STUDY OBJECTIVES The ventrolateral preoptic area (VLPO) and the orexin/hypocretin neuronal system are key regulators of sleep onset, transitions between vigilance states, and energy homeostasis. Reciprocal projections exist between the VLPO and orexin/hypocretin neurons. Although the importance of the VLPO to sleep regulation is clear, it is unknown whether VLPO neurons are involved in energy balance. The purpose of these studies was to determine if the VLPO is a site of action for orexin-A, and which orexin receptor subtype(s) would mediate these effects of orexin-A. We hypothesized that orexin-A in the VLPO modulates behaviors (sleep and wakefulness, feeding, spontaneous physical activity [SPA]) to increase energy expenditure. DESIGN AND MEASUREMENTS Sleep, wakefulness, SPA, feeding, and energy expenditure were determined after orexin-A microinjection in the VLPO of male Sprague-Dawley rats with unilateral cannulae targeting the VLPO. We also tested whether pretreatment with a dual orexin receptor antagonist (DORA, TCS-1102) or an OX2R antagonist (JNJ-10397049) blocked the effects of orexin-A on the sleep/wake cycle or SPA, respectively. RESULTS Orexin-A injected into the VLPO significantly increased wakefulness, SPA, and energy expenditure (SPA-induced and total) and reduced NREM sleep and REM sleep with no effect on food intake. Pretreatment with DORA blocked the increase in wakefulness and the reduction in NREM sleep elicited by orexin-A, and the OX2R antagonist reduced SPA stimulated by orexin-A. CONCLUSIONS These data show the ventrolateral preoptic area is a site of action for orexin-A, which may promote negative energy balance by modulating sleep/wakefulness and stimulating spontaneous physical activity and energy expenditure.
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Affiliation(s)
| | - Claudio E Perez-Leighton
- Center for Integrative Medicine and Innovative Science, Universidad Andres Bello, Santiago, Chile.,Escuela de Nutricion, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Catherine M Kotz
- Minneapolis VA Health Care System, Minneapolis, MN.,Geriatric Research Education and Clinical Center, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
| | - Charles J Billington
- Minneapolis VA Health Care System, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Medicine, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
| | - Sairam Parthasarathy
- Arizona Respiratory Center University of Arizona, Tucson, AZ.,Department of Medicine University of Arizona, Tucson, AZ
| | - Christopher M Sinton
- Arizona Respiratory Center University of Arizona, Tucson, AZ.,Department of Medicine University of Arizona, Tucson, AZ
| | - Jennifer A Teske
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ.,Minneapolis VA Health Care System, Minneapolis, MN.,Minnesota Obesity Center, University of Minnesota, Saint Paul, MN.,Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN
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Strickland JC, Rush CR, Stoops WW. Mu opioid mediated discriminative-stimulus effects of tramadol: an individual subjects analysis. J Exp Anal Behav 2015; 103:361-74. [PMID: 25664525 DOI: 10.1002/jeab.137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 01/02/2015] [Indexed: 11/12/2022]
Abstract
Drug discrimination procedures use dose-dependent generalization, substitution, and pretreatment with selective agonists and antagonists to evaluate receptor systems mediating interoceptive effects of drugs. Despite the extensive use of these techniques in the nonhuman animal literature, few studies have used human participants. Specifically, human studies have not routinely used antagonist administration as a pharmacological tool to elucidate the mechanisms mediating the discriminative stimulus effects of drugs. This study evaluated the discriminative-stimulus effects of tramadol, an atypical analgesic with monoamine and mu opioid activity. Three human participants first learned to discriminate 100 mg tramadol from placebo. A range of tramadol doses (25 to 150 mg) and hydromorphone (4 mg) with and without naltrexone pretreatment (50 mg) were then administered to participants after they acquired the discrimination. Tramadol produced dose-dependent increases in drug-appropriate responding and hydromorphone partially or fully substituted for tramadol in all participants. These effects were attenuated by naltrexone. Individual participant records indicated a relationship between mu opioid activity (i.e., miosis) and drug discrimination performance. Our findings indicate that mu opioid activity may mediate the discriminative-stimulus effects of tramadol in humans. The correspondence of generalization, substitution, and pretreatment findings with the animal literature supports the neuropharmacological specificity of the drug discrimination procedure.
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Affiliation(s)
- Justin C Strickland
- DEPARTMENT OF PSYCHOLOGY, UNIVERSITY OF KENTUCKY COLLEGE OF ARTS AND SCIENCES
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Wang C, Kotz CM. Urocortin in the lateral septal area modulates feeding induced by orexin A in the lateral hypothalamus. Am J Physiol Regul Integr Comp Physiol 2002; 283:R358-67. [PMID: 12121849 DOI: 10.1152/ajpregu.00558.2001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intermediate portion of the lateral septum (LSi) contains high levels of urocortin (UCN) peptide and type 2 corticotropin-releasing hormone (CRH) receptor (CRHR2) and has anatomic and functional connections with the lateral hypothalamus (LH). We tested the effect of UCN in the LSi on feeding. Injection of 10 or 30 pmol UCN into LSi significantly decreased feeding in food-deprived rats for 24 h without producing conditioned taste aversion (CTA). Pretreatment with a CRH receptor antagonist, alpha-helical CRH (alpha-hCRH), blocked the inhibitory effect of UCN on deprivation-induced feeding at 1 and 2 h postinjection. Furthermore, UCN in the LSi significantly decreased feeding induced by LH-injected orexin A at 2 and 4 h postinjection, and addition of alpha-hCRH blocked the inhibitory effect of UCN on orexin A-induced feeding. In conclusion, UCN significantly inhibits feeding induced by deprivation and LH-injected orexin A without producing a CTA, an effect that is mediated by CRHR2. These data define the LSi as an important site for UCN-induced anorexia and indicate that LSi UCN may influence orexin A feeding signals in the LH.
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Affiliation(s)
- Chuanfeng Wang
- Veterans Affairs Medical Center, Geriatric, Research, Education and Clinical Center and Research Service, Minneapolis 55417, USA
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Easterling KW, Holtzman SG. Central discriminative effects of morphine in rats: training via intracerebroventricular administration. Brain Res Bull 2001; 56:545-51. [PMID: 11786240 DOI: 10.1016/s0361-9230(01)00661-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
There have been studies of the discriminative effects of intracerebroventricularly (ICV)-administered morphine (MOR) in rats trained to discriminate MOR systemically, but the converse has not been done. In this study, rats were trained to discriminate between ICV (1-10 microg/3 microl, 1 h) or subcutaneous (SC) (3.0 mg/kg, 30 min) injections of MOR vs. saline/vehicle in a discrete-trial avoidance/escape procedure. On generalization testing, subjects in both the ICV- and SC-trained groups responded on the MOR-appropriate lever at ICV MOR doses < or =1-3 microg, and at SC MOR doses 2 to 3 orders of magnitude higher (vs. ICV). Naltrexone (SC) blocked the stimulus effects of MOR (ICV) equipotently in both training groups. In ICV-trained subjects, levorphanol (SC), the mu-opioid selective peptide [D-Ala2, NMePhe4, Gly-ol]-enkephalin (DAMGO) (ICV), and the enkephalinase inhibitor N-[L-(1-carboxy-2-phenyl)ethyl]-L-phenylalanyl-beta-alanine (SCH 32615) (ICV) produced complete MOR-appropriate responding, whereas the dextrorotary enantiomer of levorphanol dextrorphan (SC; < or = 3.0 mg/kg) and the delta-opioid selective peptide [D-Pen2, D-Pen5]-enkephalin (DPDPE) (ICV, < or = 0.03 mg) did not. SC-trained subjects did not generalize to SCH 32615, which suggests qualitative differences in the discriminative stimulus effects of novel drugs as a function of the route of administration of the training drug. These data demonstrate that it is feasible to train rats to discriminate an opioid administered by the ICV route, and to perform extended tests of generalization to novel drugs (SC or ICV) in rats so trained.
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Affiliation(s)
- K W Easterling
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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