RESUMO
BACKGROUND: Periaqueductal gray matter (PAG) is a brain region rich in kappa-opioid receptors (KOR). KOR in PAG mediates behavioral responses related to pain integration, and panic response, among others. Its participation in the addiction phenomena has been poorly studied. Hence, this preliminary study explored the pharmacological effects of KOR stimulation/blockade in dorsal-PAG (D-PAG) during alcohol withdrawal on anxiety-type behaviors and alcohol intake/preference. METHODS: Juvenile male Wistar rats were unexposed (A-naïve group) or exposed to alcohol for 5 weeks and then restricted (A-withdrawal group). Posteriorly, animals received intra D-PAG injections of vehicle (10% DMSO), salvinorin A (SAL-A; a selective KOR agonist), or 2-Methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine (PF-04455242; a highly selective KOR-antagonist). Subsequently, the defensive burying behavior (DBB) and alcohol intake/preference paradigms were evaluated. RESULTS: SAL-A markedly increased burying time, the height of bedding, and alcohol consumption/preference in A-withdrawal, while slightly increased the height of bedding in A-näive rats. PF-04455242 decreased both burying and immobility duration, whereas increases latency to burying, frequency of rearing, and the number of stretches attempts with no action on alcohol intake/preference in A-withdrawal rats. CONCLUSIONS: In general, stimulation/blockade of KOR in A-withdrawal animals exert higher responses compared to A-naïve ones. SAL-A produced anxiety-like behaviors and increased alcohol consumption/preference, especially/solely in the alcohol-withdrawal condition, while PF-04455242 augmented exploration with no effects on alcohol intake/preference. Our findings suggest a possible pharmacologic hyperreactivity of the KOR in PAG during alcohol withdrawal.
Assuntos
Alcoolismo , Síndrome de Abstinência a Substâncias , Ratos , Masculino , Animais , Receptores Opioides kappa/agonistas , Receptores Opioides kappa/metabolismo , Substância Cinzenta Periaquedutal , Ratos WistarRESUMO
This study aimed to investigate the protective effect of salvinorin A on the cerebral pial artery after forebrain ischemia and explore related mechanisms. Thirty Sprague-Dawley rats received forebrain ischemia for 10 min. The dilation responses of the cerebral pial artery to hypercapnia and hypotension were assessed in rats before and 1 h after ischemia. The ischemia reperfusion (IR) control group received DMSO (1 µL/kg) immediately after ischemia. Two different doses of salvinorin A (10 and 20 µg/kg) were administered following the onset of reperfusion. The 5th, 6th, and 7th groups received salvinorin A (20 µg/kg) and LY294002 (10 µM), L-NAME (10 μM), or norbinaltorphimine (norBIN, 1 μM) after ischemia. The levels of cGMP in the cerebrospinal fluid (CSF) were also measured. The phosphorylation of AKT (p-AKT) was measured in the cerebral cortex by western blot at 24 h post-ischemia. Cell necrosis and apoptosis were examined by hematoxylin-eosin staining (HE) and TUNEL staining, respectively. The motor function of the rats was evaluated at 1, 2, and 5 days post-ischemia. The dilation responses of the cerebral pial artery were significantly impaired after ischemia and were preserved by salvinorin A treatment. In addition, salvinorin A significantly increased the levels of cGMP and p-AKT, suppressed cell necrosis and apoptosis of the cerebral cortex and improved the motor function of the rats. These effects were abolished by LY294002, L-NAME, and norBIN. Salvinorin A preserved cerebral pial artery autoregulation in response to hypercapnia and hypotension via the PI3K/AKT/cGMP pathway.
Assuntos
Animais , Masculino , Ratos , Artérias Cerebrais/efeitos dos fármacos , Isquemia Encefálica/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Diterpenos Clerodânicos/farmacologia , Transdução de Sinais , Artérias Cerebrais/fisiopatologia , Isquemia Encefálica/tratamento farmacológico , Morfolinas/administração & dosagem , Cromonas/administração & dosagem , Ratos Sprague-Dawley , GMP Cíclico/líquido cefalorraquidiano , GMP Cíclico/metabolismo , NG-Nitroarginina Metil Éster , Diterpenos Clerodânicos/antagonistas & inibidores , Modelos Animais de Doenças , Naltrexona/administração & dosagem , Naltrexona/análogos & derivadosRESUMO
Salvia divinorum (Lamiaceae) is a herb native to Mexico where it is used by Mazatec shamans for spiritual and divination purposes. S. divinorum products are easily available to consumers and are used worldwide as legal highs because of the hallucinogenic effects caused mainly by salvinorin A. Highly popular videos and websites on the internet depicting the use of S. divinorum products have contributed to an increase in their consumption. Recent reports have highlighted the potential of these products to induce psychosis in consumers. In Mexico, dried leaf extracts of S. divinorum are sold in different strengths, claiming to correlate with increasing amounts of salvinorin A. In order to determine the variability of salvinorin A content between brands and to investigate possible correlation between brand strengths, this study sought to quantify salvinorin A in commercial products available in Mexico using an HPLC method. The HPLC analytical method showed a correlation coefficient R(2)>0.99, with LOD of 0.44 µg/mL and LOQ of 1.34 µg/mL. The retention time for salvinorin A was 23.09±0.95 min and the measured concentrations ranged between 8.32±0.65 and 56.52±3.77 mg/g dried leaf. The results for brand c did not show an agreement between the declared and the calculated amount of salvinorin A. Additionally, the emergence in Mexico of high strength salvia products (100×), the lack of regulation and the observed variability of salvinorin A content between brands of commercial legal highs products of S. divinorum could result in a health problem for consumers.
Assuntos
Diterpenos Clerodânicos/análise , Extratos Vegetais/análise , Psicotrópicos/química , Salvia/química , Cromatografia Líquida , Comércio , Humanos , MéxicoRESUMO
It has been shown that electrical stimulation of the mesencephalic tectum (MT) provokes defensive responses in both humans and rodents. During an emotional aversive state, some convergent studies have also demonstrated the existence of a complex interaction between endogenous opioid peptide- and γ-aminobutyric acid (GABA)-containing connections during fear-induced responses. It has been proposed that opioid neurons exert an influence on GABAergic interneurons, which, in turn, exert inhibitory tonic control on the mesencephalic excitatory pathways. Thus, opioid peptides can disinhibit neurons that are tonically inhibited by GABA, therefore, modulating the expression of defensive behavioural reactions. In the present work, we used both electric stimulation and microinjections of the GABAA receptor antagonist bicuculline in the inferior colliculus (IC) of Wistar rats in combination with microinjections of µ- and κ-opioid receptor selective agonists into the dorsal columns of periaqueductal grey matter (dPAG) to evaluate the effects on panic-like behaviours elicited by IC electrical and chemical stimulation. The present results showed that neurochemical lesions of the dPAG caused a significant impairment in the organisation of defensive responses by IC neurons, reducing the duration [t(14)=3.0; p<0.01] of defensive immobility and the duration [t(14)=2.8; p<0.05] and frequency [t(14)=2.5; p<0.05] of escape. Paradoxically, treating the dPAG with the µ-opioid receptor agonist met-enkephalin caused a significant reduction of panic-like behaviours induced by both electrical and chemical stimulation of the IC, increasing the escape behaviour threshold [F(2,23)=13.5; p<0.001] and decreasing the frequency [F(3,36)=11.7; p<0.001] and duration [F(3,36)=11.6; p<0.001] of escape and the duration of defensive immobility [F(3,36)=16.1; p<0.05]. In contrast, treating the dPAG with the κ-opioid receptor agonist salvinorin-A increased the frequency [F(3,36)=12.4; p<0.01] and duration [F(3,34)=16.1; p<0.01] of defensive immobility induced by GABAA receptor blockade in the IC. The present results suggest the existence of a complex neuronal network in the MT in which endogenous opioid peptides and GABAergic pathways interact in the control of fear-related behavioural responses.
Assuntos
Analgésicos Opioides/farmacologia , Colículos Inferiores/fisiologia , Pânico/fisiologia , Substância Cinzenta Periaquedutal/fisiologia , Receptores Opioides kappa/metabolismo , Receptores Opioides mu/metabolismo , Animais , Bicuculina/farmacologia , Diterpenos Clerodânicos/farmacologia , Estimulação Elétrica , Encefalina Metionina/farmacologia , Reação de Fuga/fisiologia , Reação de Congelamento Cataléptica/fisiologia , Antagonistas de Receptores de GABA-A/farmacologia , Ácido Ibotênico , Colículos Inferiores/efeitos dos fármacos , Masculino , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Ratos Wistar , Receptores de GABA-A/metabolismo , Receptores Opioides kappa/agonistas , Receptores Opioides mu/agonistasRESUMO
Salvia divinorum is a sage endemic to a small region of Mexico and has been traditionally used by the Mazatec Indians for divination and spiritual healing. Recently, it has gained increased popularity as a recreational drug, used by adolescents and young adults as an alternative to marijuana and LSD. Salvinorin A, the major active ingredient of the plant, is considered to be the most potent known hallucinogen of natural origin. This review surveys the current state of knowledge on the neurochemical, pharmacokinetic, and pharmacological properties of salvinorin A, the trends and motivation behind S. divinorum use, and the health problems among users of the plant's products. S. divinorum induces intense, but short-lived, psychedelic-like changes in mood and perception, with concomitant hallucinations and disorientation. Many websites have misinterpreted the limited existing research-based information on the side effects of salvia as evidence for its safety. However, data accumulated over the last few years indicate that potential health risks are associated with the use of S. divinorum, especially by teenagers, users of other substances of abuse, and individuals with underlying psychotic disturbances. Taken together, the data presented in this review point to the need for further basic and clinical studies to create a basis for the development of well-addressed prevention and treatment strategies.
Assuntos
Diterpenos Clerodânicos/química , Alucinógenos/química , Drogas Ilícitas/química , Medicina Tradicional , Salvia , Animais , Diterpenos Clerodânicos/administração & dosagem , Alucinógenos/administração & dosagem , Humanos , Drogas Ilícitas/farmacologia , MéxicoRESUMO
A planta Salvia divinorum Epling & Játiva (SDI), da família Lamiaceae, tem sido usada por séculos pela cultura mazateca e vem ganhando popularidade como droga recreacional nos últimos anos. Seu princípio ativo - Salvinorina A (SA) - é agonista dos receptores opióides kappa, com potencial psicotrópico. A utilização da planta vem crescendo na Europa e na América do Norte, apesar de ainda não existirem provas concretas sobre abuso. A presente revisão da literatura contemporânea aborda as evidências sobre o potencial de abuso de SDI, bem como o crescente uso recreacional, ainda que seja alucinógeno permitido legalmente e de fácil compra em muitos países.
The plant Salvia divinorum Epling & Játiva (SDI), of the Lamiaceae family, has been used for centuries by the Mazateca culture and has gained popularity as a recreational drug in the last years. Its active principle, Salvinorin A (SA), is a potentially psychotropic agonist of the kappa opioid receptors. The use of SDI has increased in Europe and North America, although there are no concrete proofs about abuse. The present review discusses current evidence on potential SDI abuse, as well as its increasing recreational use, although it is considered a legalized hallucinogen easily acquired in many countries.