Role of opioidergic and GABAergic neurotransmission of the nucleus raphe magnus in the modulation of tonic immobility in guinea pigs
| Autor: | Leda Menescal-de-Oliveira, Luis Felipe Souza da Silva |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Male
medicine.medical_specialty Microinjections Narcotic Antagonists Guinea Pigs Models Neurological Neurotransmission Bicuculline Inhibitory postsynaptic potential GABA Antagonists chemistry.chemical_compound hemic and lymphatic diseases Internal medicine medicine Animals Premovement neuronal activity GABA Agonists gamma-Aminobutyric Acid Opioidergic Nucleus raphe magnus Analysis of Variance Behavior Animal Morphine Muscimol Naloxone General Neuroscience Immobility Response Tonic Analgesics Opioid Endocrinology chemistry Raphe Nuclei GABAergic Neuroscience medicine.drug |
| Zdroj: | Brain Research Bulletin. 72:25-31 |
| ISSN: | 0361-9230 |
| DOI: | 10.1016/j.brainresbull.2006.12.005 |
| Popis: | Tonic immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. Previous results from our laboratory have demonstrated that nucleus raphe magnus (NRM) is also a structure involved in the modulation of TI behavior, as chemical stimulation through carbachol decreases the duration of TI in guinea pigs. In view of the fact that GABAergic and opioidergic circuits participate in the regulation of neuronal activity in the NRM and since these neurotransmitters are also involved in the modulation of TI, the objective of the present study was to evaluate the role of these circuits of the NRM in the modulation of the behavioral TI response. Microinjection of morphine (4.4 nmol/0.2 microl) or bicuculline (0.4 nmol/0.2 microl) into the NRM increased the duration of TI episodes while muscimol (0.5 nmol/0.2 microl) decreased it. The effect of morphine injection into the NRM was blocked by previous microinjection of naloxone (2.7 nmol/0.2 microl). Muscimol at 0.25 nmol did not produce any change in TI duration; however, it blocked the increased response induced by morphine. Our results indicate a facilitatory role of opioidergic neurotransmission in the modulation of the TI response within the NRM, whereas GABAergic activity plays an inhibitory role. In addition, in the present study the modulation of TI in the NRM possibly occurred via an interaction between opioidergic and GABAergic systems, where the opioidergic effect might be due to inhibition of tonically active GABAergic interneurons. |
| Databáze: | OpenAIRE |
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