Effect of electrical stimulation of central nucleus of the amygdala on morphine conditioned place preference in male rats

Document Type : Original Article


1 Department of Biology, Kazerun Branch, Islamic Azad University, Kazerun, Iran

2 Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran


Objective(s): The central nucleus of the amygdala (CeA) is one of the most important areas for the morphine reward system. This study investigated the effect of electrical stimulation of CeA on morphine conditioned place preference (CPP) in male rats.  
Materials and Methods: After anesthetizing male Wistar rats, both electrode and cannula were implanted into CeA for stimulating (low intensity: 25 μA, and high intensity: 150 μA) and injecting (lidocaine and dopamine D2 receptor antagonist), respectively. Then, CPP induced by effective (5 mg/kg) and ineffective (0.5 mg/kg) doses of morphine was evaluated for five consecutive days (n = 6 / group).
Results: The low electrical stimulation intensity of 25 μA suppressed both acquisition and expression phases, but the high intensity of 150 µA attenuated only the expression phase. On the other hand, intra-CeA administration of dopamine D2 receptor antagonist, eticlopride (2 µg/rat), with the effective dose of morphine, decreased CPP. In addition, infusion of lidocaine into the CeA inhibited morphine-induced CPP in both acquisition and expression phases with the effective dose of morphine.
Conclusion: Electrical stimulation of the CeA may play an important role in attenuating morphine induced CPP via possible changes in neurotransmitters involved in the reward system such as dopamine (DA) and gamma-aminobutyric acid (GABA).


1. Hemati K, Pourhanifeh MH, Dehdashtian E, Fatemi I, Mehrzadi S, Reiter RJ, et al. Melatonin and morphine: potential beneficial effects of co‐use. Fundam Clin Pharmacol 2021; 35:25-39.
2. Ueda H, Ueda M. Mechanisms underlying morphine analgesic tolerance and dependence. Front Biosci 2009; 14:5260-5272.
3. Volkow ND, Fowler J, Wang G, Baler R, Telang F. Imaging dopamine’s role in drug abuse and addiction. Neuropharmacol 2009; 56:3-8.
4. Wang TR, Moosa S, Dallapiazza RF, Elias WJ, Lynch WJ. Deep brain stimulation for the treatment of drug addiction. Neurosurg Focus 2018; 45:1-19.
5. Perlmutter JS, Mink JW. Deep brain stimulation. Annu Rev Neurosci 2006; 29:229-257.
6. Okun MS. Deep-brain stimulation for parkinson’s disease. N Engl J Med 2012; 367:1529-1538.
7. Kisely S, Li A, Warren N, Siskind D. A systematic review and meta‐analysis of deep brain stimulation for depression. Depress Anxiety 2018; 35:468-480.
8. Baldermann JC, Schueller T, Huys D, Becker I, Timmermann L, Jessen F, et al. Deep brain stimulation for tourette-syndrome: a systematic review and meta-analysis. Brain Stimul 2016; 9:296-304.
9. Alonso P, Cuadras D, Gabriëls L, Denys D, Goodman W, Greenberg BD, et al. Deep brain stimulation for obsessive-compulsive disorder: a meta-analysis of treatment outcome and predictors of response. PloS one 2015; 10:1-16.
10.    Alaei H, Pour MG. Stimulation and transient inactivation of ventral tegmental area modify reinstatement of acquisition phase of morphine-induced conditioned place preference in male rats. Brain Res Bull 2021; 176:130-141.
11.    Amohashemi E, Reisi P, Alaei H. Lateral habenula electrical stimulation with different intensities in combination with GABAB receptor antagonist reduces acquisition and expression phases of morphine-induced CPP. Neurosci Lett 2021; 759:135996-136001.
12.    Kargari A, Ramshini E, Alaei H, Sedighi M, Oryan S. Different current intensities electrical stimulation of prelimbic cortex of mPFC produces different effects on morphine-induced conditioned place preference in rats. Behav Brain Res 2012; 231:187-192.
13.    Batra V, Tran TLN, Caputo J, Guerin GF, Goeders NE, Wilden J. Intermittent bilateral deep brain stimulation of the nucleus accumbens shell reduces intravenous methamphetamine intake and seeking in Wistar rats. J Neurosurg 2017; 126:1339-1350.
14.    Creed M, Pascoli VJ, Lüscher C. Refining deep brain stimulation to emulate optogenetic treatment of synaptic pathology. Science 2015; 347:659-664.
15.    SABET KM, Masoudnia F, Khansefid N, BEHZADI Z. Opioid receptors of the central amygdala and morphine-induced antinociception. Iran Biomed J 2007; 11:75-80.
16.    Freedman L, Cassell M. Distribution of dopaminergic fibers in the central division of the extended amygdala of the rat. Brain Research 1994; 633:243-252.
17.    Bie B, Wang Y, Cai Y-Q, Zhang Z, Hou Y-Y, Pan ZZ. Upregulation of nerve growth factor in central amygdala increases sensitivity to opioid reward. Neuropsychopharmacology 2012; 37:2780-2788.
18.    Baxter MG, Murray EA. The amygdala and reward. Nat Rev Neurosci 2002; 3:563-573.
19.    Bardo MT, Horton DB, Yates JR. Conditioned place preference as a preclinical model for screening pharmacotherapies for drug abuse. Nonclinical Assessment of Abuse Potential for New Pharmaceuticals: Elsevier; 2015; 151-196.
20. Prus AJ, James JR, Rosecrans JA. Conditioned Place Preference. 2nd ed. 2009.
21.    Ghavipanjeh GR, Pourshanazari AA, Alaei H, Karimi S. The influence of electrical stimulation on dorsal raphe nucleus with different current intensities on morphine-induced conditioned place preference in male rats. Pharmacol Rep 2015; 67:832-836.
22.    Ghavipanjeh GR, Pourshanazari AA, Alaei H, Karimi S, Nejad MA. Effects of temporary inactivation and electrical stimulation of the dorsal raphe nucleus on morphine-induced conditioned place preference. Malays J Med Sci 2015; 22:33-40.
23.    Yan N, Chen N, Zhu H, Zhang J, Sim M, Ma Y, et al. High-frequency stimulation of nucleus accumbens changes in dopaminergic reward circuit. PLoS One 2013; 8:79318-79325.
24.    Radahmadi M, Ramshini E, Hosseini N, Karimi S, Alaei H. Effect of electrical stimulation of nucleus accumbens with low, median and high currents intensities on conditioned place preference induced by morphine in rats. Adv Biomed Res 2014; 3:14-19.
25.    Paxinos G, Watson C. The Rat Brain in Stereotaxic Coordinates: Hard Cover. 6th ed. 2006.
26.    Hao Y, Yang J, Sun J, Qi J, Dong Y, Wu CF. Lesions of the medial prefrontal cortex prevent the acquisition but not reinstatement of morphine-induced conditioned place preference in mice. Neurosci Lett 2008; 433:48-53.
27.    Shi X-D, Wang G-B, Ma Y-y, Ren W, Luo F, Cui C-L, et al. Repeated peripheral electrical stimulations suppress both morphine-induced CPP and reinstatement of extinguished CPP in rats: accelerated expression of PPE and PPD mRNA in NAc implicated. Mol Brain Res 2004; 130:124-133.
28.    Koob G, Volkow N. Neurocircuitry of addiction. Neuropsycopharmacology 2010; 35:217–238.
29.    Tzschentke TM. Review on CPP: measuring reward with the conditioned place preference (CPP) paradigm: update of the last decade. Addict Biol 2007; 12:227-462.
30.    Ardjmand A, Rezayof A, Zarrindast M-R. Involvement of central amygdala NMDA receptor mechanism in morphine state-dependent memory retrieval. Neurosci Res 2011; 69:25-31.
31.    Madhavan A, Bonci A, Whistler JL. Opioid-induced GABA potentiation after chronic morphine attenuates the rewarding effects of opioids in the ventral tegmental area. J Neurosci 2010; 30:14029-14035.
32.    Zhang Z, Tao W, Hou Y-Y, Wang W, Lu Y-G, Pan ZZ. Persistent pain facilitates response to morphine reward by downregulation of central amygdala GABAergic function. Neuropsychopharmacology 2014; 39:2263-2271.
33.    Everitt BJ, Parkinson JA, Olmstead MC, Arroyo M, Robledo P, Robbins TW. Associative processes in addiction and reward the role of amygdala‐ventral striatal subsystems. Ann N Y Acad Sci 1999; 877:412-438.
34.    Conzales C, Chesselet MF. Amygdalonigral pathway: an anterograde study in the rat with Phaseolus vulgaris leucoagglutinin (PHA‐L). J Comp Neurol 1990; 297:182-200.
35.    Leshan RL, Opland DM, Louis GW, Leinninger GM, Patterson CM, Rhodes CJ, et al. Ventral tegmental area leptin receptor neurons specifically project to and regulate cocaine-and amphetamine-regulated transcript neurons of the extended central amygdala. J Neurosci 2010; 30:5713-5723.
36.    Nikolaus S, Wittsack H-J, Beu M, Antke C, De Souza Silva MA, Wickrath F, et al. GABAergic control of nigrostriatal and mesolimbic dopamine in the rat brain. Front Behav Neurosci 2018; 12:38-50.
37.    Rezayof A, Zarrindast M-R, Sahraei H, Haeri-Rohani A. Involvement of dopamine D2 receptors of the central amygdala on the acquisition and expression of morphine-induced place preference in rat. Pharmacol Biochem Behav 2002; 74:187-197.
38.    Beninger RJ. The role of dopamine in locomotor activity and learning. Brain Res Rev 1983; 6:173-196.
39.    Beninger RJ, Miller R. Dopamine D1-like receptors and reward-related incentive learning. Neurosci Biobehav Rev 1998; 22:335-345.
40.    Li H-B, Matsumoto K, Yamamoto M, Watanabe H. NMDA but not AMPA receptor antagonists impair the delay-interposed radial maze performance of rats. Pharmacol Biochem Behav 1997; 58:249-253.
41.    Chesworth R, Corbit L. The contribution of the amygdala to reward-related learning and extinction. The Amygdala-Where Emotions Shape Perception, Learning and Memories. 2017;1:13.
42.    Ono T, Nishijo H, Uwano T. Amygdala role in conditioned associative learning. Prog Neurobiol 1995; 46:401-422.
43.    Khatami L, Khodagholi F, Motamedi F. Reversible inactivation of interpeduncular nucleus impairs memory consolidation and retrieval but not learning in rats: a behavioral and molecular study. Behav Brain Res 2018; 342:79-88.