The role of opioid peptides in memory and learning

Izquierdo, I; Dias, Regina Davison; Souza, Dércio Bernardes de; Carrasco, M. Angélica; Elisabetsky, Elaine; Perry, Marcos L. S.

doi:10.1016/s0166-4328(80)80079-9

Cited by 4 publications

(4 citation statements)

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“…In the CPA paradigm, animals associate spontaneous pain with the environment of a compartment. Opioids play an important role in learning and memory (Izquierdo et al., ). There is a possibility that morphine interfered with the acquisition of this relationship, thus confounding data interpretation.…”

Section: Discussionmentioning

confidence: 99%

Electroacupuncture alleviates affective pain in an inflammatory pain rat model

Meng

Xin

et al. 2012

European Journal of Pain

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Pain has both sensory-discriminative and emotional-affective dimensions. Previous studies demonstrate that electroacupuncture (EA) alleviates the sensory dimension but do not address the affective. An inflammatory pain rat model, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a conditioned place avoidance (CPA) test to determine whether EA inhibits spontaneous pain-induced affective response and, if so, to study the possibility that rostral anterior cingulate cortex (rACC) opioids underlie this effect. Male Sprague-Dawley rats (250–275g, Harlan) were used. The rats showed place aversion (i.e. affective pain) by spending less time in a pain-paired compartment after conditioning than during a preconditioning test. Systemic non-analgesic morphine (0.5 and 1.0 mg/ kg, i.p.) inhibited the affective reaction, suggesting that the affective dimension is underpinned by mechanisms different from those of the sensory dimension of pain. Morphine at 0.5 and at 1 mg/kg did not induce reward. Rats given EA treatment before pain-paired conditioning at GB 30 showed no aversion to the pain-paired compartment, indicating that EA inhibited the affective dimension. EA treatment did not produce reward or aversive effect. Intra-rACC administration of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr amide (CTOP), a selective mu opioid receptor antagonist, but not norbinaltorphimine (nor-BNI), a selective kappa opioid receptor antagonist, blocked EA inhibition of the affective dimension. These data demonstrate that EA activates opioid receptors in the rACC to inhibit pain-induced affective responses and that EA may be an effective therapy for both the sensory-discriminative and the affective dimensions of pain.

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Section: Discussionmentioning

confidence: 99%

Electroacupuncture alleviates affective pain in an inflammatory pain rat model

Meng

Xin

et al. 2012

European Journal of Pain

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“…Several studies have shown the important role of opioid transmission in learning and memory (Izquierdo et al 1980;McGaugh and Baratti 1985;Ragozzino and Gold 1994;Vaccarino et al 1998), and several studies have focused on the effects of morphine on memory. In most of these studies, pretraining administration of this opiate induced learning/ memory deficits in rodents tested in avoidance paradigms that use foot shocks as unconditioned stimuli (Izquierdo 1979;Ragozzino et al 1992;Gold 1994, 1995;McNay and Gold 1998;Aguilar et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Effects of morphine on the plus-maze discriminative avoidance task: role of state-dependent learning

et al. 2005

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“…In the present work, we attempted to develop another quantitative method, for the assay of a different GE (namely GE-B5). GE-B5 is very similar in structure to Leu-enkephalin (L-ENK, Tyr-Gly-Gly-Phe-Leu), an endogenous opioid with profound effects on CNS [11,12], differing only at the second amino acid residue. Interestingly, this variation causes, compared to L-ENK, a reduction of GE-B5 opioid activity on the μ and Δ receptors (1.2 and 4.2 times lower, respectively) and opioid affinity (1.2 and 1.7 times lower, respectively) [1].…”

Section: Discussionmentioning

confidence: 99%