Activation of transient receptor potential vanilloid 1 (TRPV1), a calcium permeable channel expressed in primary sensory neurons, induces the release of glutamate from their central and peripheral afferents during normal acute and pathological pain. However, little information is available regarding the glutamate release mechanism associated with TRPV1 activation in primary sensory neurons. To address this issue, we investigated the expression of vesicular glutamate transporter (VGLUT) in TRPV1-immunopositive (+) neurons in the rat trigeminal ganglion (TG) under normal and complete Freund’s adjuvant (CFA)-induced inflammatory pain conditions using behavioral testing as well as double immunofluorescence staining with antisera against TRPV1 and VGLUT1 or VGLUT2. TRPV1 was primarily expressed in small and medium-sized TG neurons. TRPV1+ neurons constituted approximately 27% of all TG neurons. Among all TRPV1+ neurons, the proportion of TRPV1+ neurons coexpressing VGLUT1 (VGLUT1+/ TRPV1+ neurons) and VGLUT2 (VGLUT2+/TRPV1+ neurons) was 0.4% ± 0.2% and 22.4% ± 2.8%, respectively. The proportion of TRPV1+ and VGLUT2+ neurons was higher in the CFA group than in the control group (TRPV1+ neurons: 31.5% ± 2.5% vs. 26.5% ± 1.2%, VGLUT2+ neurons: 31.8% ± 1.1% vs. 24.6% ± 1.5%, p < 0.05), whereas the proportion of VGLUT1+, VGLUT1+/TRPV1+, and VGLUT2+/TRPV1+ neurons did not differ significantly between the CFA and control groups. These findings together suggest that VGLUT2, a major isoform of VGLUTs, is involved in TRPV1 activation-associated glutamate release during normal acute and inflammatory pain.

Introduction
Materials and Methods
    1. 실험동물
    2. 염증성 통증 동물모델에 대한 행동분석
    3. 면역형광조직화학법을 위한 조직 준비
    4. 면역형광염색법
    5. 면역형광조직화학법에 사용된 항체들의 특이성 조사
    6. 면역형광염색법 결과의 정량적 분석
Results
    1. 삼차신경절에서 TRPV1 발현 신경세포의 VGLUTs 공존
    2. 염증성 통증 동물 모델
    3. 염증성 통증 유발군에서 TRPV1과 VGLUT 발현의 변화
Discussion
    1. 정상 삼차신경절 TRPV1+ 신경세포의 VGLUT 발현
    2. 염증성 통증 시 삼차신경절 신경세포에서 TRPV1과VGLUT2 발현의 증가
References

• Hye Min Han(Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University)
• Yi Sul Cho(Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University)
• Yong Chul Bae(Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University) Correspondence to