bq-123 and Lung-Neoplasms

The peptide endothelin-1 (ET1), which was originally identified as a vasoconstrictor, has emerged as a critical regulator of a number of painful conditions, including inflammatory pain and tumor-associated pain. There is considerable pharmacological evidence supporting a role for endothelin A receptors (ET(A)) in mediating ET1-induced pro-algesic functions. ET(A) receptors are expressed in small-diameter nociceptive neurons, but also found in a variety of other cell types in peripheral tissues, including immune cells, keratinocytes, endothelial cells, which have the potential to modulate nociception. To elucidate the functional contribution of ET(A) receptors expressed in sensory neurons towards the functions of the ET1 axis in pathological pain states, we undertook a conditional gene deletion approach to selectively deplete expression of ET(A) in sensory nerves, preserving expression in non-neural peripheral tissues; the expression of ET(B) remained unchanged. Behavioural and pharmacological experiments showed that only late nociceptive hypersensitivity caused by ET1 is abrogated upon a loss of ET(A) receptors on nociceptors and further suggest that ET1-induced early nociceptive hypersensitivity involves activation of ET(A) as well as ET(B) receptors in non-neural peripheral cells. Furthermore, in the context of alleviation of cancer pain and chronic inflammatory pain by ET(A) receptor antagonists, we observed in corresponding mouse models that the contribution of ET(A) receptors expressed in nociceptors is most significant. These results help understand the role of ET(A) receptors in complex biological processes and peripheral cell-cell interactions involved in inflammatory and tumor-associated pain.

Topics: Analysis of Variance; Animals; Carcinoma; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Ganglia, Spinal; Hyperalgesia; Lung Neoplasms; Mice; Mice, Inbred C57BL; Mice, Transgenic; NAV1.8 Voltage-Gated Sodium Channel; Nociceptors; Pain; Pain Measurement; Peptides, Cyclic; Receptor, Endothelin A; RNA, Messenger; Sensory Receptor Cells; Sodium Channels; Time Factors; Tubulin

Endothelin-1 may be involved in the pathogenesis of asthma by causing bronchial smooth muscle constriction and airway remodelling. Bronchial epithelial cells represent an important source of endothelin-1 in this disease, and increased release of epithelial cell-derived endothelin-1 may contribute to the genesis of subepithelial fibrosis by promoting fibroblast proliferation and collagen production. In this study, we demonstrate that endothelin-1 upregulates fibronectin gene expression and fibronectin release in bronchial epithelial cells via an ETA receptor. Fibronectin is an important component of the extracellular matrix which is deposited in excess in the subepithelial area of asthmatic bronchial mucosa, and it represents a potent chemotactic factor for fibroblasts. Thus, endothelin-1 may induce subepithelial fibrosis both directly and by the autocrine mechanism reported here.

Topics: Blotting, Northern; Bronchi; Cells, Cultured; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelins; Epithelium; Fibronectins; Gene Expression; Glycopeptides; Humans; Kinetics; Lung Neoplasms; Peptides, Cyclic; Receptors, Endothelin; RNA, Messenger; Time Factors; Vasoconstrictor Agents; Viper Venoms