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Effect of neonatal capsaicin treatment on neural activity in the medullary dorsal horn of neonatal rats evoked by electrical stimulation to the trigeminal afferents: an optical, electrophysiological, and quantitative study.
Brain Res. 2001 Jul 06; 906(1-2):1-12.BR

Abstract

To elucidate which glutamate receptors, NMDA or non-NMDA, have the main role in synaptic transmission via unmyelinated afferents in the trigeminal subnucleus caudalis (the medullary dorsal horn), and to examine the early functional effects of neonatal capsaicin treatment to the subnucleus caudalis, optical recording, field potential recording, and quantitative study using electron micrographs were employed. A medulla oblongata isolated from a rat 5--7 days old was sectioned horizontally 400-microm thick or parasagittally and stained with a voltage-sensitive dye, RH482 or RH795. Single-pulse stimulation with high intensity to the trigeminal afferents evoked optical responses mainly in the subnucleus caudalis. The optical signals were composed of two phases, a fast component followed by a long-lasting component. The spatiotemporal properties of the optical signals were well correlated to those of the field potentials recorded simultaneously. The fast component was eliminated by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 10 microM), while the long-lasting component was not. The latter increased in amplitude under a condition of low Mg(2+) but was significantly reduced by DL-2-amino-5-phosphonovaleric acid (AP5; 30 microM). Neonatal capsaicin treatment also reduced the long-lasting component markedly. In addition, the decreases in the ratio of unmyelinated axons to myelinated axons and in the ratio of unmyelinated axons to Schwann cell subunits of trigeminal nerve roots both showed significant differences (P<0.05, Student's t-test) between the control group and the neonatal capsaicin treatment group. This line of evidence indirectly suggests that synaptic transmission via unmyelinated afferents in the subnucleus caudalis is mediated substantially by NMDA glutamate receptors and documented that neonatal capsaicin treatment induced a functional alteration of the neural transmission in the subnucleus caudalis as well as a morphological alteration of primary afferents within several days after the treatment.

Authors+Show Affiliations

Department of Dental Anesthesiology, Hokkaido University Graduate School of Dental Medicine, Sapporo 060-8586, Japan. takuma@den.hokudai.ac.jp

Pub Type(s)

Journal Article

Language

eng

PubMed ID

11430856

Citation

Takuma, S. "Effect of Neonatal Capsaicin Treatment On Neural Activity in the Medullary Dorsal Horn of Neonatal Rats Evoked By Electrical Stimulation to the Trigeminal Afferents: an Optical, Electrophysiological, and Quantitative Study." Brain Research, vol. 906, no. 1-2, 2001, pp. 1-12.
Takuma S. Effect of neonatal capsaicin treatment on neural activity in the medullary dorsal horn of neonatal rats evoked by electrical stimulation to the trigeminal afferents: an optical, electrophysiological, and quantitative study. Brain Res. 2001;906(1-2):1-12.
Takuma, S. (2001). Effect of neonatal capsaicin treatment on neural activity in the medullary dorsal horn of neonatal rats evoked by electrical stimulation to the trigeminal afferents: an optical, electrophysiological, and quantitative study. Brain Research, 906(1-2), 1-12.
Takuma S. Effect of Neonatal Capsaicin Treatment On Neural Activity in the Medullary Dorsal Horn of Neonatal Rats Evoked By Electrical Stimulation to the Trigeminal Afferents: an Optical, Electrophysiological, and Quantitative Study. Brain Res. 2001 Jul 6;906(1-2):1-12. PubMed PMID: 11430856.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of neonatal capsaicin treatment on neural activity in the medullary dorsal horn of neonatal rats evoked by electrical stimulation to the trigeminal afferents: an optical, electrophysiological, and quantitative study. A1 - Takuma,S, PY - 2001/6/30/pubmed PY - 2001/9/14/medline PY - 2001/6/30/entrez SP - 1 EP - 12 JF - Brain research JO - Brain Res. VL - 906 IS - 1-2 N2 - To elucidate which glutamate receptors, NMDA or non-NMDA, have the main role in synaptic transmission via unmyelinated afferents in the trigeminal subnucleus caudalis (the medullary dorsal horn), and to examine the early functional effects of neonatal capsaicin treatment to the subnucleus caudalis, optical recording, field potential recording, and quantitative study using electron micrographs were employed. A medulla oblongata isolated from a rat 5--7 days old was sectioned horizontally 400-microm thick or parasagittally and stained with a voltage-sensitive dye, RH482 or RH795. Single-pulse stimulation with high intensity to the trigeminal afferents evoked optical responses mainly in the subnucleus caudalis. The optical signals were composed of two phases, a fast component followed by a long-lasting component. The spatiotemporal properties of the optical signals were well correlated to those of the field potentials recorded simultaneously. The fast component was eliminated by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 10 microM), while the long-lasting component was not. The latter increased in amplitude under a condition of low Mg(2+) but was significantly reduced by DL-2-amino-5-phosphonovaleric acid (AP5; 30 microM). Neonatal capsaicin treatment also reduced the long-lasting component markedly. In addition, the decreases in the ratio of unmyelinated axons to myelinated axons and in the ratio of unmyelinated axons to Schwann cell subunits of trigeminal nerve roots both showed significant differences (P<0.05, Student's t-test) between the control group and the neonatal capsaicin treatment group. This line of evidence indirectly suggests that synaptic transmission via unmyelinated afferents in the subnucleus caudalis is mediated substantially by NMDA glutamate receptors and documented that neonatal capsaicin treatment induced a functional alteration of the neural transmission in the subnucleus caudalis as well as a morphological alteration of primary afferents within several days after the treatment. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/11430856/Effect_of_neonatal_capsaicin_treatment_on_neural_activity_in_the_medullary_dorsal_horn_of_neonatal_rats_evoked_by_electrical_stimulation_to_the_trigeminal_afferents:_an_optical_electrophysiological_and_quantitative_study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0006-8993(01)02448-9 DB - PRIME DP - Unbound Medicine ER -