Fine-tuning of defensive behaviors in the dorsal periaqueductal gray by atypical neurotransmitters

Brazilian Journal of Medical and Biological Research

M.v. Fogaça²  S.f. Lisboa²  D.c. Aguiar¹  F.a. Moreira¹  F.v. Gomes²  P.c. Casarotto²  F.s. Guimarães² 

[1] ,Universidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de FarmacologiaRibeirão Preto SP ,Brasil

关键词: Endocannabinoid;    Anandamide;    Nitric oxide;    Endovanilloid;    TRPV1;   

DOI  :  10.1590/S0100-879X2012007500029

来源: SciELO

【 摘 要 】

This paper presents an up-to-date review of the evidence indicating that atypical neurotransmitters such as nitric oxide (NO) and endocannabinoids (eCBs) play an important role in the regulation of aversive responses in the periaqueductal gray (PAG). Among the results supporting this role, several studies have shown that inhibitors of neuronal NO synthase or cannabinoid receptor type 1 (CB1) receptor agonists cause clear anxiolytic responses when injected into this region. The nitrergic and eCB systems can regulate the activity of classical neurotransmitters such as glutamate and γ-aminobutyric acid (GABA) that control PAG activity. We propose that they exert a ‘fine-tuning’ regulatory control of defensive responses in this area. This control, however, is probably complex, which may explain the usually bell-shaped dose-response curves observed with drugs that act on NO- or CB1-mediated neurotransmission. Even if the mechanisms responsible for this complex interaction are still poorly understood, they are beginning to be recognized. For example, activation of transient receptor potential vanilloid type-1 channel (TRPV1) receptors by anandamide seems to counteract the anxiolytic effects induced by CB1 receptor activation caused by this compound. Further studies, however, are needed to identify other mechanisms responsible for this fine-tuning effect.

【 授权许可】

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