Study of the neural basis of striatal modulation of the jaw-opening reflex.
Previous experimental data from this laboratory demonstrated the participation of the striatum and dopaminergic pathways in central nociceptive processing. The objective of this study was to examine the possible pathways and neural structures associated with the analgesic action of the striatum. The experiments were carried out in rats anesthetized with urethane. The jaw-opening reflex (JOR) was evoked by electrical stimulation of the tooth pulp of lower incisors and recorded in the anterior belly of the digastric muscles. Intrastriatal microinjection of apomorphine, a nonspecific dopamine agonist, reduced or abolished the JOR amplitude. Electrolytic or kainic acid lesions, unilateral to the apomorphine-injected striatum, of the globus pallidus, substantia nigra pars reticulata, subthalamic nucleus and bilateral lesion the rostroventromedial medulla (RVM), blocked the inhibition of the JOR by striatal stimulation. These findings suggest that the main output nuclei of the striatum and the RVM may be critical elements in the neural pathways mediating the inhibition of the reflex response, evoked in jaw muscles by noxious stimulation of dental pulp.
Barceló
Ana C
AC
Cátedra de Fisiología, Universidad de Buenos Aires, Buenos Aires, Argentina.
Fillipini
B
B
Pazo
Jorge Horacio
JH
D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D003782:Dental Pulp / Q000502:physiology; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology; D004558:Electric Stimulation; D004576:Electromyography; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D007568:Jaw / Q000502:physiology*; D007608:Kainic Acid / Q000633:toxicity; D008297:Male; D008845:Microinjections; D009132:Muscles / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014520:Urethane
D018491:Dopamine Agonists; D018690:Excitatory Amino Acid Agonists; D014520:Urethane; D001058:Apomorphine; D007608:Kainic Acid