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The effects of microinjection of morphine into thalamic nucleus submedius on formalin-evoked nociceptive responses of neurons in the rat spinal dorsal horn.
Neurosci Lett. 2006 Jun 19; 401(1-2):103-7.NL

Abstract

Previous studies have indicated that the thalamic nucleus submedius (Sm), as an ascending component, is involved in an endogenous analgesic system consisting of spinal cord-Sm-ventrolateral orbital cortex (VLO)-periaqueductal gray (PAG)-spinal cord loop. To investigate the action of opioid in this antinociception pathway, the effects of microinjection of morphine and naloxone into the Sm on the formalin-induced nociceptive responses of neurons in the spinal dorsal horn were determined in the anesthetized rat. Formalin (5%, 50 microl) subcutaneously injected into unilateral hindpaw produced a biphasic nociceptive response which was similar to that obtained from assessing the nociceptive behavior either in the relative magnitude of response or the time course. A unilateral microinjection of morphine (5 microg, 0.5 microl) into the Sm 15 min after formalin injection significantly depressed the second phasic responses of neurons induced by formalin, and this effect was significantly attenuated by pre-microinjection of opioid receptor antagonist naloxone (1 microg, 0.5 microl) into the same site. The results suggest that the Sm is involved in opioid receptor-mediated antinociceptive effect on the persistent nociception through depression of the nociceptive transmission at the spinal cord level.

Authors+Show Affiliations

Department of Physiology and Pathophysiology, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, PR China.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16556485

Citation

Zhao, Mei, et al. "The Effects of Microinjection of Morphine Into Thalamic Nucleus Submedius On Formalin-evoked Nociceptive Responses of Neurons in the Rat Spinal Dorsal Horn." Neuroscience Letters, vol. 401, no. 1-2, 2006, pp. 103-7.
Zhao M, Li Q, Tang JS. The effects of microinjection of morphine into thalamic nucleus submedius on formalin-evoked nociceptive responses of neurons in the rat spinal dorsal horn. Neurosci Lett. 2006;401(1-2):103-7.
Zhao, M., Li, Q., & Tang, J. S. (2006). The effects of microinjection of morphine into thalamic nucleus submedius on formalin-evoked nociceptive responses of neurons in the rat spinal dorsal horn. Neuroscience Letters, 401(1-2), 103-7.
Zhao M, Li Q, Tang JS. The Effects of Microinjection of Morphine Into Thalamic Nucleus Submedius On Formalin-evoked Nociceptive Responses of Neurons in the Rat Spinal Dorsal Horn. Neurosci Lett. 2006 Jun 19;401(1-2):103-7. PubMed PMID: 16556485.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of microinjection of morphine into thalamic nucleus submedius on formalin-evoked nociceptive responses of neurons in the rat spinal dorsal horn. AU - Zhao,Mei, AU - Li,Qiang, AU - Tang,Jing-Shi, Y1 - 2006/03/23/ PY - 2006/01/04/received PY - 2006/02/25/revised PY - 2006/02/27/accepted PY - 2006/3/25/pubmed PY - 2006/9/29/medline PY - 2006/3/25/entrez SP - 103 EP - 7 JF - Neuroscience letters JO - Neurosci Lett VL - 401 IS - 1-2 N2 - Previous studies have indicated that the thalamic nucleus submedius (Sm), as an ascending component, is involved in an endogenous analgesic system consisting of spinal cord-Sm-ventrolateral orbital cortex (VLO)-periaqueductal gray (PAG)-spinal cord loop. To investigate the action of opioid in this antinociception pathway, the effects of microinjection of morphine and naloxone into the Sm on the formalin-induced nociceptive responses of neurons in the spinal dorsal horn were determined in the anesthetized rat. Formalin (5%, 50 microl) subcutaneously injected into unilateral hindpaw produced a biphasic nociceptive response which was similar to that obtained from assessing the nociceptive behavior either in the relative magnitude of response or the time course. A unilateral microinjection of morphine (5 microg, 0.5 microl) into the Sm 15 min after formalin injection significantly depressed the second phasic responses of neurons induced by formalin, and this effect was significantly attenuated by pre-microinjection of opioid receptor antagonist naloxone (1 microg, 0.5 microl) into the same site. The results suggest that the Sm is involved in opioid receptor-mediated antinociceptive effect on the persistent nociception through depression of the nociceptive transmission at the spinal cord level. SN - 0304-3940 UR - https://www.unboundmedicine.com/medline/citation/16556485/The_effects_of_microinjection_of_morphine_into_thalamic_nucleus_submedius_on_formalin_evoked_nociceptive_responses_of_neurons_in_the_rat_spinal_dorsal_horn_ DB - PRIME DP - Unbound Medicine ER -