This study investigated the role of opioid, adenosine, bradykinin, and calcitonin-gene related peptide (CGRP) receptors, and potential ‘cross-talk’ among suspected G-protein coupled receptors in a humoral model of remote ischemic preconditioning (rIPC) cardioprotection. Compared to Control dialysate (from non-preconditioned donor rabbit blood), rIPC dialysate (from remotely preconditioned blood) reduced cell death in rabbit cardiomyocytes following simulated ischemia and reperfusion. Non-selective, δ-, or κ-opioid receptor blockade and non-selective adenosine receptor blockade abolished rIPC dialysate protection; whereas, bradykinin B2 and CGRP receptor blockade had no effect. Non-selective adenosine receptor blockade fully and partially abolished protection by κ- and δ-opioid receptors, respectively. Multiple reaction monitoring mass spectrometry detected low levels of adenosine, and other preconditioning substances, in the dialysate. An increase in extracellular adenosine was not detected during opioid-induced preconditioning to explain this cross-talk. These results suggest that δ-opioid, κ-opioid, adenosine receptors, and opioid-adenosine cross-talk are involved in rIPC of freshly isolated cardiomyocytes.

This study investigated the role of opioid, adenosine, bradykinin, and calcitonin-gene related peptide (CGRP) receptors, and potential ‘cross-talk’ among suspected G-protein coupled receptors in a humoral model of remote ischemic preconditioning (rIPC) cardioprotection. Compared to Control dialysate (from non-preconditioned donor rabbit blood), rIPC dialysate (from remotely preconditioned blood) reduced cell death in rabbit cardiomyocytes following simulated ischemia and reperfusion. Non-selective, δ-, or κ-opioid receptor blockade and non-selective adenosine receptor blockade abolished rIPC dialysate protection; whereas, bradykinin B2 and CGRP receptor blockade had no effect. Non-selective adenosine receptor blockade fully and partially abolished protection by κ- and δ-opioid receptors, respectively. Multiple reaction monitoring mass spectrometry detected low levels of adenosine, and other preconditioning substances, in the dialysate. An increase in extracellular adenosine was not detected during opioid-induced preconditioning to explain this cross-talk. These results suggest that δ-opioid, κ-opioid, adenosine receptors, and opioid-adenosine cross-talk are involved in rIPC of freshly isolated cardiomyocytes.

Les récepteurs couplés aux protéines G forment des complexes multimériques comprenant protéines G et effecteurs. Nous cherchons à caractériser de tels complexes comprenant les récepteurs opioïdes delta (DOR) et les canaux Kir3, qui nous sont d’intérêt vu leur implication dans l’analgésie des opioïdes. Des expériences d’immunopurification, de BRET et de liaison GTPgS ont été réalisées à l’intérieur de cellules HEK293 transfectées. Les canaux Kir3 ont été co-immunopurifiés avec les DOR, suggérant une interaction spontanée entre récepteur et effecteur. Des essais BRET ont corroboré que l’interaction était présente dans des cellules vivantes et nous ont permis d’identifier une interaction spontanée et spécifique entre DOR/Gg et Gg/Kir3, indiquant leur coexistence en un même complexe. Puisque l’activation du récepteur implique la présence de changements conformationnels à l’intérieur de celui-ci, nous étions intéressés à vérifier si l’information conformationnelle circule à partir du récepteur lié au ligand jusqu’à l’effecteur en aval. Ainsi, nous avons déterminé l’effet de différents ligands sur le signal BRET généré par les paires suivantes : DOR/Gbg, DOR/Kir3 et Kir3/Gbg. Nous avons constaté une modulation de l’interaction DOR/Gbg et Gbg/Kir3 suivant l’ordre d’efficacité des ligands à stimuler la protéine G, ce que nous n’avons pas observé entre DOR et Kir3. Donc, nous concluons que l’information conformationnelle circule du récepteur au canal Kir3 via la protéine Gbg. Ces résultats nous ont permis de développer un biosenseur BRET (EYFP-Gg2/Kir3.1-Rluc) qui pourrait être utilisé dans le criblage à haut débit afin de détecter de nouvelles molécules ayant une grande efficacité à activer les canaux Kir3. / G protein-coupled receptors form multimeric complexes comprising G protein and effectors. We want to characterize such complexes comprising delta opioid receptors (DOR) and Kir3 channels, which interest us due to their involvement in opioid analgesia. Immunopurification, BRET and GTPgS binding experiments were done in transfected HEK293 cells. Kir3 channels were co-immunopurified with DOR, implying a spontaneous interaction between the receptor and effector. BRET assays corroborated the presence of this interaction in living cells and allowed us to identify a spontaneous and specific interaction between DOR/Gg and Gg/Kir3, indicating their co-existence within the same complex. Since the activation of the receptor implies it undergoes conformational changes, we were interested in evaluating if the conformational information flows from the ligand-bound receptor until the downstream effector. Hence, we determined the effect of different ligands on the BRET signal that was generated by the following pairs: DOR/Gbg, DOR/Kir3 and Kir3/Gbg. We noticed a modulation of the DOR/Gbg and Gbg/Kir3 interactions that followed the order of efficacy of the ligands to activate the G protein, which we did not observe between DOR and Kir3. Therefore, we concluded that the conformational information flows from the receptor to the Kir3 channel via the Gbg protein. These results allowed us to develop a BRET biosensor (EYFP-Gg2/Kir3.1-Rluc), which could be used in high throughput screening to detect new molecules that activate Kir3 channels with high efficacy.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.

Submitted by JOSIMARÍ CRISTIANE TIEMANN ARAÚJO (marietiemannpharma@gmail.com) on 2018-07-30T15:47:21Z No. of bitstreams: 1 Disssertação_Josy PDF.pdf: 1879909 bytes, checksum: b868bf7a67063f92000e7e3e22b828b0 (MD5) / Approved for entry into archive by Laura Akie Saito Inafuko (linafuko@assis.unesp.br) on 2018-07-30T18:58:11Z (GMT) No. of bitstreams: 1 tiemann-araujo_jc_me_assis.pdf: 1879909 bytes, checksum: b868bf7a67063f92000e7e3e22b828b0 (MD5) / Made available in DSpace on 2018-07-30T18:58:11Z (GMT). No. of bitstreams: 1 tiemann-araujo_jc_me_assis.pdf: 1879909 bytes, checksum: b868bf7a67063f92000e7e3e22b828b0 (MD5) Previous issue date: 2018-03-04 / Fármacos antidepressivos como os inibidores seletivos de recaptação de serotonina são utilizados no tratamento da ansiedade, pânico e outros transtornos mentais. Os efeitos desejados ocorrem somente após administração crônica, em torno de 3 a 4 semanas após o início do tratamento, com aumento dos sintomas de ansiedade no início da terapia farmacológica, ocasionando a descontinuidade do uso desses fármacos. Além disso, há relatos de resistência a esse tipo de tratamento. Visando encontrar soluções para tais problemas, fundamentados em estudos que mostraram que mecanismos opioides favorecem a atividade inibitória da serotonina em neurônios da Substância Cinzenta Pereiaquedutal Dorsal que modulam a fuga/pânico, o presente estudo teve por objetivo investigar o efeito da Buprenorfina, um agonista parcial de receptores µ-opioide e antagonista de receptores κ-opioide, como agente ansiolítico e anti-pânico, como também avaliar se o efeito ansiolítico e antipânico da Fluoxetina seriam antecipados pela associação com a Buprenorfina. Foram realizados 3 experimentos utilizando ratos machos Wistar com peso médio de 200g no início das sessões experimentais: 1. Tratamento agudo com Buprenorfina IP nas doses (0,015mg/Kg, 0,03mg/Kg 0,3mg/Kg), tendo como controle positivo o Alprazolam IP (4mg/Kg); 2. Tratamento subcrônico 3 dias com Buprenorfina IP (0,3mg/Kg); 3. Tratamento agudo com Buprenorfina (0,3mg/Kg) - associado ao tratamento subcrônico com Fluoxetina 3 dias IP, (10mg/Kg). Após os tratamentos, os animais foram submetidos à avaliação comportamental no Labirinto em T Elevado (LTE) e, subsequentemente, ao Campo Aberto e no Teste de Transição Claro-Escuro. No experimento 1 o teste comportamental foi repetido 24 horas após a primeira avaliação comportamental. Os resultados mostraram que a Buprenorfina nas doses maiores diminuiu a latência das esquivas, sem alteração das fugas no LTE, diferentemente do que se constatou no tratamento agudo com o Alprazolam, o qual diminuiu também as esquivas, mas aumentou a latência nas fugas, efeitos esses interpretados respectivamente como, ansiolítico e panicolítico. Vinte e quatro horas depois não se constatou mais efeito do Alprazolam, e o efeito da Buprenorfina sobre as esquivas só foi identificado na maior dose e apenas na LB. Em nenhuma das duas situações houve aumento de atividade motora. No teste de Transição Claro-Escuro não se constatou efeito expressivo nas condições estudadas, apenas possibilitou a escolha da maior dose para a continuidade do estudo, já que a intermediária aumentou a atividade motora nesse teste 24h após a injeção. A Buprenorfina administrada subcronicamente também diminuiu as esquivas, sem afetar a latência das fugas e o comportamento motor no campo aberto. Também não se identificou alterações no Teste de Transição Claro-escuro. A Buprenorfina antecipou o efeito ansiolítico da Fluoxetina, sem afetar as respostas relacionadas com a manifestação do pânico. Entretanto não houve confirmação dos achados no outro teste de ansiedade. Conclui-se que a Buprenorfina, administrada de forma aguda e subcrônica, diminuiu os comportamentos defensivos relacionados com a ansiedade generalizada, e antecipou o efeito ansiolítico da Fluoxetina, podendo se constituir em uma opção relevante no tratamento dos transtornos de ansiedade na clínica, devido à sua baixa capacidade de causar efeitos adversos e também diante da possibilidade de antecipar os efeitos benéficos da fluoxetina, apenas com uma injeção / Antidepressant drugs such as selective serotonin reuptake inhibitors are used in the treatment of anxiety, panic and other mental disorders. The desired effects occur only after chronic administration, around 3 to 4 weeks after starting treatment, with increased anxiety symptoms at the beginning of pharmacological therapy, causing the discontinuation of the use of these drugs. In addition, there are reports of resistance to this type of treatment. Aiming to find solutions for such problems, based on studies that showed that opioid mechanisms favor the serotonin inhibitory activity in SCPD neurons that modulate scape / panic, the present study aimed to investigate the effect of Buprenorphine, a partial agonist of μ receptors - opioid and antagonist κ receptor - opioid as anxiolytic and anti-panic agents as well as assessing whether the anxiolytic and antipanic effect of Fluoxetine would be anticipated by association with Buprenorphine.Three experiments were performed using male Wistar rats weighing 200g at the beginning of the experimental sessions: 1. Acute treatment with Buprenorphine IP at doses (0,015mg / kg, 0,03mg / kg 0,3mg / kg) or Alprazolam IP (4mg / kg); 2. Subchronic treatment 3 days with Buprenorphine IP (0,3mg / kg); 3. Acute treatment with Buprenorphine (0,3mg / kg) - associated to the subchronic treatment with Fluoxetine 3 days IP, (10mg / kg). After the treatments, the animals were submitted to behavioral evaluation in the elevated T maze (LTE) and subsequently to the Open Field and the Light-Dark Transition Test. In experiment 1 the behavioral test was repeated 24 hours after the first behavioral evaluation. The results showed that Buprenorphine in the larger doses decreased the manifestation of the elusions, without alterations of the scapes in the LTE, differently from what was observed in the acute treatment with Alprazolam, which also reduced the elusive ones, but increased the latency in the scapes, interpreted respectively as anxiolytic and panicolitic. Twenty-four hours later no effect of Alprazolam was found, and the effect of Buprenorphine on the avoidance was only identified at the highest dose and only at LB. There was no increase in motor activity in either of the two situations. In the Light-Dark Transition test, no significant effect was observed in the conditions studied, it only allowed the choice of the highest dose for the continuity of the study, since the intermediary increased the motor activity in this test 24 hours after the injection.Subchronic administration of buprenorphine also decreased the avoidances without affecting the scapes and motor behavior in the open field. Also, no changes were identified in the Light-Dark Transition Test. Buprenorphine anticipated the anxiolytic effect of Fluoxetine, without affecting the responses related to the manifestation of panic. However, there was no confirmation of the findings in the other anxiety test. It was concluded that acute and subchronic administration of Buprenorphine decreased the defensive behaviors related to generalized anxiety, and anticipated the anxiolytic effect of Fluoxetine, which may constitute a relevant option in the treatment of anxiety disorders in the clinic due to the its low ability to cause adverse effects and also the possibility of anticipating the beneficial effects of fluoxetine with an injection alone

Morphine is a natural opioid which is used in medicine due to his potent analgesic and sedative effects. In the forefront of scientific interest is a chronic usage of opioids which can lead to a development of drug addiction. Morphine role in oxidative stress was described in last years. It was revealed its protective potencial by many studies. However, some studies described its pro-oxidative effect. The aim of this study was to determinate effect of chronic morphine on cell survival after oxidative stress caused by H202 analog - tBHP in the SH-SY5Y neuroblastoma cell line. The results verified morphine protective effect against oxidative stress. The highest protective effect of morphine was achieved in a concetration of 10 µM. It was desribed that morphine can induce activation of mu-opioid (MOR) and Toll-like 4 (TLR4) receptors signalling pathway on molecular level. The aim of this thesis was to evaluate the role of MOR a TLR4 in protective effect of morphine against oxidative stress by two methods. Firstly, it was used tests of oxidative stress on cell viability. The obtained results demonstrated majority role of TLR4 and minory role of MOR. Afterwards, we assesed changes in the expression of MOR a TLR4 after chronic morphine by SDS-PAGE electrophoresis. Results of these experiments did not...

Submitted by Ana Sant'Ana (ana.mattos@ufscar.br) on 2016-09-26T13:33:25Z No. of bitstreams: 1 DissCCS.pdf: 2483023 bytes, checksum: 3acdef41810eb8722e4f4c44f4ebb688 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-06T14:03:42Z (GMT) No. of bitstreams: 1 DissCCS.pdf: 2483023 bytes, checksum: 3acdef41810eb8722e4f4c44f4ebb688 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-06T14:03:54Z (GMT) No. of bitstreams: 1 DissCCS.pdf: 2483023 bytes, checksum: 3acdef41810eb8722e4f4c44f4ebb688 (MD5) / Made available in DSpace on 2016-10-06T14:04:00Z (GMT). No. of bitstreams: 1 DissCCS.pdf: 2483023 bytes, checksum: 3acdef41810eb8722e4f4c44f4ebb688 (MD5) Previous issue date: 2016-07-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The endogenous opioids are involved in analgesia, thermoregulation and physiological responses to various stressful stimuli such as infection, psychological stress and hypoxia. The mu and kappa receptors in the hypothalamus play a role in endotoxin-induced fever and hypoxia-induced anapyrexia (opposite response to fever), respectively. In addition, periaqueductal gray (PAG), which express both mu and kappa receptors, is involved in defence and thermoregulatory responses. Thus, our hypothesis is that mu and kappa opioid receptors in the PAG modulate the restraint-induced fever in rats by activating and inhibiting this response, respectively. To this end, body temperature (Tb) and heat loss index (HLI; inference for heat conservation/loss) and oxygen consumption (VO ; inference for thermogenesis) of unanesthetized Wistar rats submitted or not to restraint stress, was monitored before and after intra-PAG microinjection of the selective mu opioid receptor antagonist (CTAP; 1 and 10 μg/ 100 nL/ animal), the selective kappa-opioid receptor antagonist (nor-BNI; 1 and 4 μg/ 100 nL/ animal), or vehicle (saline; 100nL/ animal). CTAP and nor-BNI did not change the Tb or the HLI of the animals in euthermia. During the restraint stress, Tb increased in all groups of animals. However, this effect was significantly lower in animals treated with CTAP, and significantly higher in animals treated with nor-BNI. No treatment affected HLI, but CTAP decreased thermogenesis and nor-BNI increased thermogenesis. The results indicate that the mu and kappa opioid receptors in the PAG of rats play a pyrogenic and antipyretic role, respectively, during fever induced by restraint stress and these receptors in PAG may not be essential for the maintenance of Tb during euthermia. / Os opióides endógenos estão envolvidos na analgesia, termorregulação e respostas fisiológicas a vários estímulos estressantes, como infecção, estresse psicológico e hipóxia. Os receptores mu e kappa no hipotálamo desempenham um papel na febre induzida por endotoxina e anapirexia induzida por hipoxia (resposta oposta à febre), respectivamente. Além disso, a substância cinzenta periaquedutal (PAG), que expressa ambos os receptores mu e kappa, está envolvida na defesa e respostas de termorregulação. Assim, nossa hipótese é que os receptores opióides mu e kappa na PAG modulam a febre induzida por contenção em ratos, ativando e inibindo esta resposta, respectivamente. Para este fim, a temperatura corporal (Tc) e o índice de perda de calor (IPC; inferência para a conservação/perda de calor) e o consumo de oxigênio (VO ; inferência para a termogênese) de ratos Wistar não anestesiados submetidos ou não ao estresse contenção, foi monitorado antes e depois microinjeção intra-PAG do antagonista seletivo do receptor opióide mu (CTAP; 1 e 10 μg/ 100 nL/ animal), antagonista seletivo do receptor opióide kappa (nor-BNI; 1 e 4 μg/ 100 nL/ animal) ou veículo (solução salina; 100 nL / animal). A microinjeção de CTAP ou nor-BNI não alterou a Tc ou IPC dos animais em eutermia. Durante o estresse de contenção, a Tc aumentou em todos os grupos de animais. No entanto, este efeito foi significativamente menor no grupo de animais tratados com CTAP, e significativamente maior em animais tratados com nor-BNI. Nenhum tratamento afetou o IPC, mas o CTAP diminuiu a termogênese e o nor-BNI aumentou a termogênese. Os resultados indicam que os receptores opióides mu e kappa na PAG de ratos desempenham um papel pirogênico e antipirético, respectivamente, durante a febre induzida pelo estresse de contenção e estes receptores na PAG podem não ser essenciais para a manutenção de Tc durante eutermia.

INTRODUÇÃO: Tramadol é conhecido como um fármaco analgésico de ação central utilizado no tratamento de dores de intensidades moderada a forte. Efeito analgésico local já foi demonstrado. É, em parte, semelhante ao efeito anestésico local, mas outros mecanismos permanecem desconhecidos. O papel de receptores opioides periféricos na analgesia do tramadol na dor pós-operatória não é conhecido. Neste estudo, foi estudado o papel dos receptores opioides no efeito analgésico local do tramadol em modelo de dor por incisão plantar. MÉTODOS: Ratos machos jovens foram submetidos à incisão plantar e no primeiro dia pós-incisão foram divididos em quatro grupos: Grupo IP I-SF/SF - 50 uL de solução de NaCl 0,9% foram injetados na região plantar da pata posterior homolateral à incisão e, 15 minutos depois, novamente injetada a mesma quantidade de solução; Grupo IP II-SF/T_homo - 50 uL de NaCl 0,9% foram injetados na região plantar da pata homolateral e, 15 minutos depois, injetados 50 µL solução contendo 5 mg tramadol; Grupo IP III-SF/T_contra -50 uL de NaCl 0,9% foram injetados na região plantar da pata contralateral e, 15 minutos depois, 50 uL de solução contendo 5 mg de tramadol; Grupo IP IV-Nal/T_homo - 50 uL de solução contendo 200 ug de naloxona foram injetados na pata homolateral e, 15 minutos depois, 50 uL de solução contendo 5mg de tramadol foi injetada. Antes de receberem as injeções, os limiares de retirada da pata por estímulo mecânico produzido por analgesímetro eletrônico de von Frey foram medidos, e, depois da administração dos fármacos, os limiares de retirada foram avaliados nos tempos 15, 30, 45 e 60 minutos após a administração dos fármacos. O mesmo procedimento foi utilizado no segundo dia pós-incisão. As expressões proteicas dos receptores opioide ? (DOR) e µ (MOR) foram avaliadas usando técnica de immunoblotting de gânglios de raízes dorsais homolaterais (L3, L4, L5 e L6) de grupos de animais sem incisão e após 1, 2, 3 e 7 dias de animais submetidos à incisão plantar. RESULTADOS: A incisão plantar gerou marcada hiperalgesia mecânica que foi revertida por tramadol intraplantar nos dois dias. O tramadol intraplantar em pata contralateral não antagonizou a hiperalgesia mecânica, a naloxona antagonizou parcialmente o efeito analgésico do tramadol no primeiro dia pós-incisão, e antagonizou completamente no segundo dia pós-incisão. A expressão proteica de DOR aumentou no 2º, 3º e 7º dias pós-incisão, a expressão de MOR não se modificou. CONCLUSÕES: O tramadol apresentou efeito analgésico local após estímulo mecânico e esse efeito foi antagonizado por naloxona no segundo dia pós-incisão. A expressão de DOR aumentou após a incisão plantar / BACKGROUND: Tramadol is known as a central acting analgesic drugused for the treatment of moderate to severe pain. Local analgesic effect was already demonstrated. It is in part due to local anesthetic-like effect, but other mechanisms remain unclear. The role of peripheral opioid receptors in the local analgesic effect in postoperative pain is not known. In this study, we examined the role of peripheral opioid receptors in the local analgesic effect of tramadol in the plantar incision pain model. METHODS: Young male Wistar rats were submitted to plantar incision and in the first postoperative day (POD1) were divided into four groups:IP I-SF/SF,50 uL of 0.9% NaCl solution were injected in the plantar aspect of the homolateral hindpaw and again after 15 minutes; IP II-SF/T_homo, 50 uL of 0.9% NaCl solution were injected in the plantar aspect of the homolateral hindpaw and, 15 minutes later, 50 µL of solution containing 5 mg tramadol were injected in the same hindpaw; IP III-SF/T_contra, 50 uL of 0.9% NaCl were injected in the plantar aspect of the contralateral hindpaw and, 15 minutes later, 50 uL of solution containing 5 mg tramadol were injected in the same hindpaw; IP IVNal/T_homo, 50 uL of naloxone (200 ug) solution were injected in the homolateral hindpaw and 15 minutes later 50 µL of solution containing 5 mg tramadol were injected. Before receiving the assigned drugs, baseline withdrawal thresholds for mechanical hyperalgesia using electronic von Frey were measured, then, after receiving the assigned drugs, withdrawal thresholds were measured at 15, 30, 45 and 60 min after drug injection. The same procedure was repeated in POD2. u opioid receptor (MOR) and opioid receptor (DOR) protein expressions were evaluated using immunoblotting after removal of ipsilateral dorsal root ganglia (L3, L4, L5 and L6) in groups of rats non submitted to plantar incision and 1, 2, 3 and 7 days after incision. RESULTS: Plantar incision led to marked mechanical hyperalgesia that was reversed with intraplantar tramadol in both days. Contralateral tramadol did not affect mechanical hyperalgesia and naloxone antagonized partially intraplantar tramadol in POD1, and antagonized completely in POD2. DOR expression in DRGs increased in POD2, POD3 and POD7, MOR expression did not change. CONCLUSIONS: Tramadol presented local analgesic effect after mechanical stimuli and this effect was antagonized by naloxone in the second post incision day. DOR increased expression after plantar incision

It has recently been discovered that the effect of morphine can significantly reduce the tissue damage that occurs during myocardial ischemia. The molecular mechanisms by which morphine acts on the heart are still little understood. The aim of this thesis was to monitor the effect of chronic 27-day and 10-day administration of low (1 mg/kg/day) and high (10 mg/kg/ day) doses of morphine on the expression of selected G-protein-coupled receptors (GPCR) and on the expression and activity of adenylyl cyclase (AC). Chronic (27 days) morphine treatment reduced the expression of к-opioids receptors, but 10-day morphine exposure did not influence the expression of these receptors. Assessment of β1- and β2-AR by immunoblot technique did not show any significant change in the expression, but the more accurate determination of β-AR expression using the saturation binding studies revealed that 27-day treatment with high doses of morphine appreciable increased the total number of these receptors. Administration of high doses of morphine led to marked up-regulation of adenylyl cyclase (AC) isoforms V/VI, and the amount of AC decreased proportionally with the time of discontinuation of morphine administration. Low doses of morphine up- regulated AC only during 27-day administration. Chronic morphine exposure did...

The exact role of opioid receptors in drug addiction and modulatory mechanism of action of monovalent cations on these receptors are still not fully understood. Our results support the view that the mechanism of addiction to morphine is primarily based on desensitization of μ- and δ-opioid receptors. Desenzitization of agonist response proceeds already at the level of G protein functional activity. Long-term exposure of rats to morphine resulted in increase of number of δ-opioid receptors and change of their sensitivity to sodium ions. Analysis of the effect of different monovalent ions on agonist binding in δ-OR- Gi1α (Cys351 -Ile351 )-HEK293 cell line confirmed the preferential sensitivity of δ-opioid receptor to sodium ions. We have distinguished the high- and low-affinity Na+ sites. Biophysical analysis of interaction of lithium, sodium, potassium and cesium ions with plasma membranes isolated from HEK293 cells with the help of fluorescent probes indicated that monovalent ions interact, in low-affinity manner, with the polar, membrane-water interface of membrane bilayer. Key words: morphine, forebrain cortex, opioid receptors, G proteins, monovalent ions, plasma membrane, fluorescence spectroscopy.