Attenuation of neuropathic manifestations by local block of the activities of the ventrolateral orbito-frontal area in the rat

• Published in: Neuroscience 2003-09, Vol.120 (4), p.1093-1104
• Main Authors: Baliki, M, Al-Amin, H.A, Atweh, SF, Jaber, M, Hawwa, N, Jabbur, S.J, Apkarian, A.V, Saadé, N.E
• Format: Article
• Language: English
• Subjects: 6-hydrooxydopamine; 6-hydroxydopamine; 6-OHDA; Adrenergic Agents - toxicity; allodynia; Anesthetics, Local - administration & dosage; Anesthetics, Local - therapeutic use; Animals; Biological and medical sciences; Cold Temperature; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Disease Models, Animal; Electricity - adverse effects; Excitatory Amino Acid Agonists - toxicity; Female; Hindlimb - innervation; Hindlimb - physiology; Hot Temperature; hyperalgesia; Hyperalgesia - physiopathology; kainic acid; Kainic Acid - toxicity; Lidocaine - administration & dosage; Lidocaine - therapeutic use; Medical sciences; Mononeuropathies - chemically induced; Mononeuropathies - drug therapy; Mononeuropathies - physiopathology; Nerve Block - methods; Nervous system (semeiology, syndromes); Neurology; nociceptive behavior; Oxidopamine - toxicity; PAG; Pain - chemically induced; Pain - drug therapy; Pain - physiopathology; Pain Measurement; Pain Threshold - drug effects; Pain Threshold - physiology; paw withdrawal duration; periaqueductal gray; Physical Stimulation; Prefrontal Cortex - anatomy & histology; Prefrontal Cortex - physiology; PWD; Rats; Rats, Sprague-Dawley; Reference Values; SNI; somatic sensorimotor cortex; Somatosensory Cortex - physiology; Somatosensory Cortex - surgery; spared nerve injury; submedius; thermal nociception; ventral orbital; ventral-lateral orbital; VLO; wononeuropathy
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(03)00408-1

Clinical and recent imaging reports demonstrate the involvement of various cerebral prefrontal areas in the processing of pain. This has received further confirmation from animal experimentation showing an alteration of the threshold of acute nociceptive reflexes by various manipulations in the orbito-frontal cortical areas. The present study investigates the possible involvement of this area in the modulation of neuropathic manifestations in awake rats. Several groups of rats were subjected to mononeuropathy following the spared nerve injury model, known to produce evident tactile and cold allodynia and heat hyperalgesia. The activity of the ventrolateral orbital areas was selectively blocked by using either chronic or acute injection of lidocaine, electrolytic lesion, or chemical lesion with kainic acid or 6-hydroxydopamine (6-OHDA). The effects of these manipulations were compared with those following lesion of the somatic sensorimotor cortical areas. Local injection of lidocaine resulted in a reversible depression of all neuropathic manifestations while electrolytic or chemical lesions elicited transient attenuation affecting mainly the heat hyperalgesia and to a lesser extent the cold allodynia. The magnitude of the observed effects with the different procedures used can be ranked as follows: 6-OHDA