Immunolocalization of vesicular glutamate transporter 2 and exocytosis-related proteins in afferent nerve endings innervating taste buds in the rat incisive papilla

Anat Histol Embryol. 2023 Jul;52(4):531-537. doi: 10.1111/ahe.12911. Epub 2023 Feb 24.

Abstract

The present study aimed to investigate the immunolocalization of vesicular glutamate transporter (VGLUT) 1 and 2, and proteins associated with exocytosis, i.e., core components of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex (synaptosomal-associated protein of 25 kDa, syntaxin 1, and vesicle-associated membrane protein 2) and synaptotagmin-1 (Syt1), in incisive papillary taste buds of rats using double-indirect immunofluorescence. No VGLUT1 immunoreactivity was observed, whereas VGLUT2-immunoreactive punctate products were closely associated with guanine nucleotide-binding protein G(t) subunit α3-immmunoreactive cells in taste buds. VGLUT2 was immunolocalized in P2X3 purinoceptor-expressing afferent nerve endings. Synaptosomal-associated protein of 25 kDa, syntaxin 1, and vesicle-associated membrane protein 2 were immunolocalized in nerve endings containing VGLUT2-immunoreactive products as well as a few cells in taste buds. VGLUT2 was co-immunolocalized in some intragemmal nerve endings immunoreactive for Syt1, a calcium sensor implicated in vesicle membrane fusion. The present results suggest that afferent nerve endings innervating incisive taste buds release glutamate by exocytosis to modulate taste cell function.

Keywords: SNARE complex; afferent nerve endings; incisive papilla; taste buds; vesicular glutamate transporter.

MeSH terms

  • Animals
  • Exocytosis / physiology
  • Nerve Endings / metabolism
  • Rats
  • Syntaxin 1 / metabolism
  • Taste Buds* / metabolism
  • Vesicle-Associated Membrane Protein 2 / metabolism
  • Vesicular Glutamate Transport Protein 2 / metabolism

Substances

  • Vesicular Glutamate Transport Protein 2
  • Vesicle-Associated Membrane Protein 2
  • Syntaxin 1