Reinnervated nerves contribute to the secretion function and regeneration of denervated submandibular glands in rabbits.

ABSTRACT

This study aimed to investigate the contribution of redistributed nerves in the secretory function and regeneration of a denervated submandibular gland (SMG). The postganglionic parasympathetic and sympathetic denervated SMGs of rabbits were wrapped in polyester or acellular dermal matrices to block nerve regeneration either partially or completely. Submandibular glands were removed 4, 8, 16, and 24 wk after the operation and examined histologically. Furthermore, the aquaporin-5 (AQP5), muscarinic-3 (M3), and ß1-adrenergic receptors were evaluated by immunofluorescence and western blot analysis. After denervation, salivary flow was decreased and acinar cells were atrophic, and the expression levels of the M3, ß1-adrenergic, and AQP5 receptors were decreased. However, both impaired secretion function and atrophic parenchyma were gradually ameliorated with the growing redistribution of parasympathetic and sympathetic nerves. Apoptosis was markedly inhibited and expression of the M3, ß1-adrenergic, and AQP5 receptors was increased after reinnervation. In contrast, SMGs without reinnervated nerves maintained hyposecretion and atrophic parenchyma. In conclusion, reinnervated nerves in a rabbit's denervated SMG played an important role in the secretion function and regeneration of SMGs via up-regulation of the expression of neurotransmitter receptors and AQP5.