Abstract
Vesicular monoamine transporters (VMATs) mediate transmitter uptake into neurosecretory vesicles. There are two VMAT isoforms, VMAT1 and VMAT2, coded by separate genes and displaying different cell distributions and pharmacological properties. We examined the effect of stress on expression of VMATs in the rat adrenal medulla. Under basal conditions, VMAT1 is widely expressed in all adrenal chromaffin cells while VMAT2 is co‐localized with tyrosine hydroxylase (TH) but not phenylethanolamine N‐methyltransferase (PNMT), indicating its expression in norepinephrine (NE)‐, but not epinephrine (Epi)‐ synthesizing chromaffin cells. In rats exposed to immobilization stress (IMO), there was no change in levels of VMAT1 mRNA, while VMAT2 mRNA was elevated after single 2 hr IMO or repeated IMO daily for 6 days. The changes in VMAT2 mRNA were reflected by increased VMAT2 protein after repeated IMO. Immunofluorescence revealed an increased number of cells expressing VMAT2 following repeated IMO and its colocalization with PNMT in some chromaffin cells. The findings suggest an adaptive mechanism in chromaffin cells whereby enhanced catecholamine storage capacity facilitates more efficient utilization of the well characterized heightened catecholamine biosynthesis with repeated IMO stress.(Supported by NIH grant NS28869)
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
