Cultured nodose ganglia neurons co‐express thromboxane A2 receptor and TRPV1 mRNA

Abstract

Previous studies from this laboratory have revealed that the arachidonic acid metabolite, thromboxane A2 (TxA2), stimulates vagal afferent nerves and elicits cardiovascular and pulmonary reflexes. Stimulation of sensory nerves by TxA2 could involve a neuronal TxA2 receptor (TP) since we have recently reported that TxA2 receptor mRNA is expressed in a subpopulation of cultured neuronal cells of the rabbit nodose ganglia. The present study was designed to further characterize the afferent vagal neurons that express TxA2 receptor mRNA. Since TxA2 is released during inflammation or trauma we hypothesize that TP is expressed in TxA2 nociceptive (pain-sensing) neurons. This hypothesis was tested using multiplex single-cell RT-PCR on cultured nodose ganglion neurons from rabbit. Individual cells were isolated from culture and placed in an RT-PCR reaction buffer containing primers for neurofilament medium (NFM), TP, and the capsaicin receptor (TRPV1). NFM was used as a positive neuronal marker, while the presence of TRPV1 was used to distinguish nociceptive neurons. 70% (55 of 79) of the NFM positive cells contained TRPV1 mRNA while 25% (20 of 79) of the NFM positive cells contained TP mRNA. Nearly two-thirds (13 of 20) of the TP positive cells were also positive for the TRPV1 mRNA. The presence of TP mRNA in TRPV1 positive neurons may indicate that TxA2 may activate nociceptive reflexes during events such as myocardial ischemia. Hanke was supported by an NIGMS IMSD project GM62232. Wacker was supported by IRACDA post doctoral fellowship GM63651