Periaqueductal grey CB1 cannabinoid and metabotropic glutamate subtype 5 receptors modulate changes in rostral ventromedial medulla neuronal activities induced by subcutaneous formalin in the rat

Autor: Loredana Mariani, Daniela Vita, Mariantonietta Scafuro, F. Rossi, Sabatino Maione, V. de Novellis, Ida Marabese, Enza Palazzo
Přispěvatelé: DE NOVELLIS, Vito, Mariani, L., Palazzo, Enza, Vita, D., Marabese, Ida, Scafuro, Mariantonietta, Rossi, Francesco, Maione, Sabatino
Rok vydání: 2005
Předmět:
Male
Pyridines
medicine.medical_treatment
Action Potentials
Receptors
Metabotropic Glutamate
Benzoates
chemistry.chemical_compound
Piperidines
Receptor
Cannabinoid
CB1
Periaqueductal Gray
Drug Interactions
pain
Glutamate receptor antagonist
WIN 55
212-2
Pain Measurement
Neurons
Analgesics
Medulla Oblongata
General Neuroscience
Anesthesia
NMDA receptor
Rimonabant
medicine.drug
medicine.medical_specialty
Injections
Subcutaneous
Morpholines
Glycine
ON-cell
OFF-cell
Naphthalenes
Formaldehyde
Internal medicine
Reaction Time
medicine
Animals
metabotropic glutamate receptor
Rats
Wistar
Dose-Response Relationship
Drug
WIN 55
212–2
in vivo extracellular recording
Benzoxazines
Rats
Endocrinology
Metabotropic receptor
chemistry
Chromones
Metabotropic glutamate receptor
Pyrazoles
Cannabinoid receptor antagonist
Rostral ventromedial medulla
Cannabinoid
Excitatory Amino Acid Antagonists
Zdroj: Neuroscience. 134:269-281
ISSN: 0306-4522
Popis: This study was undertaken to analyze the involvement of periaqueductal gray (PAG) cannabinoid or group I metabotropic glutamate receptors in the formalin-induced changes on the rostral ventromedial medulla (RVM) ON- and OFF-cells activities. S.c. injection of formalin into the hind paw produced a transient decrease (4–6 min) followed by a longer increase (25–35 min) in tail flick latencies. Formalin also increased basal activity in RVM ON-cells (42+/- 7%) and decreased it in OFF-cells (35+/-4%). Intra-PAG microinjection of (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo[ 1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone mesylate (WIN 55,212–2) (2 nmol/rat), a cannabinoid receptor agonist, prevented the formalin-induced changes in RVM cell activities. Higher dosages of WIN 55,212–2 (4–8 nmol/rat) increased the tail flick latencies, delayed the tail flick-related onset to ON-cell burst, and decreased the duration of OFFcell pause. Furthermore, WIN 55,212–2 at a dosage of 8 nmol/ rat decreased RVM ON-cell (57+/-7%) and increased OFF-cell ongoing activities (26+/-4%). These effects were prevented by N-piperidino-5-(4-chlorophenyl)-1-(2,4dichlorophenyl)-4-methyl- 3-pyrazolecarboxamide SR141716A, (1 pmol/rat), a CB1 cannabinoid receptor antagonist, or by 2-methyl-6-(phenylethynyl) pyridine (MPEP 20 nmol/rat), a selective mGlu5 glutamate receptor antagonist. T7-(hydroxyimino) cyclopropa[b]chromen- 1*-carboxylate ethyl ester (CPCOOE/50 nmol/rat) and (S)-(+)-alpha-amino-4-carboxy-2-methylbenzeneacetic acid (LY367385, 20 nmol/rat), selective mGlu1 glutamate receptor antagonists, were ineffective in preventing the WIN-induced effects. This study suggests that s.c. injection of formalin modifies RVM neuronal activities and this effect is prevented by PAG cannabinoid receptor stimulation. Moreover, the physiological stimulation of PAG mGlu5, but not mGlu1 glutamate receptors, seems to be required for the cannabinoid-mediated effect.
Databáze: OpenAIRE
Externí odkaz: