Tumor necrosis factor‐α stimulation of calcitonin gene‐related peptide expression and secretion from rat trigeminal ganglion neurons

Abstract

Expression of the neuropeptide calcitonin gene-related peptide (CGRP) in trigeminal ganglion is implicated in neurovascular headaches and temporomandibular joint disorders. Elevation of cytokines contributes to the pathology of these diseases. However, a connection between cytokines and CGRP gene expression in trigeminal ganglion nerves has not been established. We have focused on the effects of the cytokine tumor necrosis factor-a (TNF-a). TNFR1 receptors were found on the majority of CGRP-containing rat trigeminal ganglion neurons. Treatment of cultures with TNF-a stimulated CGRP secretion. In addition, the intracellular signaling intermediate from the TNFR1 receptor, ceramide, caused a similar increase in CGRP release. TNF-a caused a coordinate increase in CGRP promoter activity. TNF-a treatment activated the transcription factor NF-jB, as well as the Jun Nterminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase pathways. The importance of TNF-a induction of MAP kinase pathways was demonstrated by inhibiting MAP kinases with pharmacological reagents and gene transfer with an adenoviral vector encoding MAP kinase phosphatase-1 (MKP-1). We propose that selective and regulated inhibition of MAP kinases in trigeminal neurons may be therapeutically beneficial for inflammatory disorders involving elevated CGRP levels.

Control of the Calcitonin Gene-related Peptide Enhancer by Upstream Stimulatory Factor in Trigeminal Ganglion Neurons

“…6A). The degree of activation was consistent with previous reports in which MEK1 was transfected to trigeminal ganglia cultures (27,28). When cells were treated with USF2 siRNA, MEKK activation was compromised by 50% (Fig.…”

“…In addition to ERK, JNK and p38 are also important in CGRP promoter activity (28). However, the downstream target of MAP kinases was not known.…”

“…Adenoviral Infections of Trigeminal Ganglia CulturesAdrCGRP-luc, an adenovirus containing the 1.25-rCGRP fused with firefly luciferase in pGL3 has been described (28). The AdrCGRP-Bam-luc adenoviral vector has a BamHI linker inserted into the 1.25-rCGRP.…”

“…USF1 and USF2 are also phosphorylated in response to phorbol ester and forskolin stimulation (25,26). Because the CGRP 18-bp enhancer is stimulated by the ERK MAP kinase pathway (27) and probably other MAP kinases (28), it is possible that MAP kinases may also activate the CGRP promoter via USF proteins in trigeminal neurons.…”

Repression of calcitonin gene-related peptide expression in trigeminal neurons by a Theobroma cacao extract

“…Primary cultures of trigeminal ganglia were established based on our previously published protocols (Durham and Russo, 1999;Bowen et al, 2006). Briefly, cells from ganglia isolated from 3-5-day-old rats were resuspended in L15 medium containing 10% fetal bovine serum (Atlanta Biologicals, Norcross, GA), 50 mM glucose, 250 μM ascorbic acid, 8 μM glutathione, 2mM glutamine, and 10 ng/ml mouse 2.5 S nerve growth factor (Alomone Laboratories, Jerusalem, Israel).…”