Gene expression of histamine H1 receptor in guinea pig primary sensory neurons: a relationship between H1 receptor mRNA-expressing neurons and peptidergic neurons.
Pharmacological studies have suggested that a subgroup of primary sensory neurons is responsive to histamine via the histamine H1 receptor. We addressed this issue using in situ hybridization histochemistry with a cRNA probe for the guinea pig H1 receptor gene. About 15% of the trigeminal and lumber dorsal root ganglion (DRG) neurons, but none of nodose ganglion neurons, were intensely labeled with this probe. The H1 receptor mRNA-positive neurons were exclusively small in size, and were demonstrated to give rise to unmyelinated fibers by ultrastructural analysis of isolectin B4-labeling. However, the H1 receptor mRNA-expressing DRG neurons were not immunoreactive to substance P (SP) and calcitonin gene-related peptide (CGRP). A marked increase in the number of mRNA-positive DRG neurons were observed 1-5 days after a crush injury of the sciatic nerve (3-4-fold of the control value). These neurons turned mRNA-positive after the nerve crush were also mainly small-sized. The mRNA signals were detected in many peptidergic (SP/CGRP) neurons, in contrast to the normal state. On the other hand, in the neurons which showed intense labeling in the normal condition, the mRNA signals were down-regulated. These results suggest that primary sensory neurons include two kinds of H1 receptor-expressing sensory neurons, one expressing H1 receptor mRNAs in the normal state and the other up-regulating the mRNAs following the peripheral nerve damage.
Kashiba
H
H
Department of Physiology, Kansai College of Oriental Medicine, 2-11-1 Wakaba, Kumatori, Sennan, Osaka 590-0433, Japan.
Fukui
H
H
Morikawa
Y
Y
Senba
E
E
D000818:Animals; D019771:Axotomy; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics*; D002772:Cholera Toxin; D015536:Down-Regulation / Q000235:genetics; D005727:Ganglia, Spinal / Q000737:chemistry / Q000166:cytology; D015870:Gene Expression / Q000502:physiology; D006168:Guinea Pigs; D006735:Horseradish Peroxidase; D017403:In Situ Hybridization; D008297:Male; D008854:Microscopy, Electron; D009475:Neurons, Afferent / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis; D011969:Receptors, Histamine H1 / Q000235:genetics* / Q000378:metabolism; D012584:Sciatic Nerve / Q000737:chemistry / Q000293:injuries; D013373:Substance P / Q000235:genetics*; D015854:Up-Regulation / Q000235:genetics
D012333:RNA, Messenger; D011969:Receptors, Histamine H1; C052635:cholera toxin, B subunit-horseradish peroxidase; D013373:Substance P; D002772:Cholera Toxin; D006735:Horseradish Peroxidase; D015740:Calcitonin Gene-Related Peptide