Expression of acetylated histone 3 in the spinal cord and the effect of morphine on inflammatory pain in rats.
In this study, a rat model of inflammatory pain was produced by injecting complete Freund's adjuvant into the hind paw, and the expression of acetylated histone 3 in the spinal cord dorsal horn was examined using immunohistochemical staining. One day following injection, there was a dramatic decrease in acetylated histone 3 expression in spinal cord dorsal horn neurons. However, on day 7, expression recovered in adjuvant-injected rats. While acetylated histone 3 labeling was present in dorsal horn neurons, it was more abundant in astrocytes and microglial cells. The recovery of acetylated histone 3 expression was associated with a shift in expression of the protein from neurons to glial cells. Morphine injection significantly upregulated the expression of acetylated histone 3 in spinal cord dorsal horn neurons and glial cells 1 day after injection, especially in astrocytes, preventing the transient downregulation. Our results indicate that inflammatory pain induces a transient downregulation of acetylated histone 3 in the spinal cord dorsal horn at an early stage following adjuvant injection, and that this effect can be reversed by morphine. Thus, the downregulation of acetylated histone 3 may be involved in the development of inflammatory pain.
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410013, Hunan Province, China ; Department of Histology and Embryology, Hunan University of Traditional Chinese Medicine, Changsha 410208, Hunan Province, China.
Hua
H
Li
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410013, Hunan Province, China.
Changqi
C
Li
Department of Anesthesia, Second Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China.
Ruping
R
Dai
Department of Anesthesia, Second Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China.
Xudan
X
Shi
Department of Anesthesia, Second Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China.
Junmei
J
Xu
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410013, Hunan Province, China.
Jianyi
J
Zhang
Department of Human Physiology, Flinders University, South Australia, Australia.
Xinfu
X
Zhou
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410013, Hunan Province, China.
Zhiyuan
Z
Li
Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha 410013, Hunan Province, China.
Xuegang
X
Luo
acetylated histone 3; hyperalgesia; inflammation; morphine; neurobiology; spinal cord