Denervation of taste buds in the rabbit

Abstract

Twenty-five rabbits were used to study the effect of glossopharyngeal nerve transection upon the number, size and cellular constitution of the taste buds. The glossopharyngeal nerve was cut o n one side, the other being left undisturbed as a control. The animals were sacrificed i n groups of three after 7, 10, 14, 21, and 30 days, and 2 and 4 months after the operation. Seven days after the operation the size and number of intragemmal cells were decreased in the taste buds. The taste pores with hairlets passing through them disappeared. The number of taste buds on circumvallate papillae decreased. After ten days taste buds in both types of papillae showed signs of degeneration. Fourteen days after the operation there was a marked decrease in size and number of taste buds. The circumvallate papillae now possessed no taste buds. After 21 days few taste buds were present in foliate gutters. These consisted of one or two sustentacular cells each. After 30 days there were no taste buds on foliate papillae, and thickness of the epithelium lining the gutters was decreased. Two or four months after denervation, the foliate gutters were shallow and some had become flattened. The importance of the gustatory nerve for development and maintenance of the normal status of the taste buds is discussed.Many investigators (Meyer, 1897; Olmsted, '20, '21, '22; Whiteside, '26; Torrey, '34, '40; Guth, '57, '58) have confirmed the observation that mammalian taste buds disappear after denervation and reappear following regeneration of the supplying gustatory nerve. Robbin ('67) stated that after denervation of frog taste buds, there was shrinkage and decrease in their size. He also postulated that the gustatory nerve was concerned with maintenance of adult cells, and control of DNA synthesis and mitosis of germinative cells. Several investigations have been performed to determine whether non-gustatory nerves can also stimulate the development of taste buds. The lingual nerve was used in the hedgehog (Boeke, '17) and dog (Olmsted and Pinger, '36; Arey and Monzingo, '42). In each of these studies, hypoglossallingual nerve anastmosis was performed, directing the regenerating hypoglossal fibers to the lingual epithelium. The results of these studies were varied. Guth ('58) using the glossopharyngeal nerve in the cat, concluded that all but a small number of taste buds on the ipsilateral circumvallate papillae disappeared after unilateral transection of the nerve. Re-appearance of taste buds occurred upon re-innervation of the papillae by either the glossopharyngeal or vagus nerve, but re-innervation by the hypoglossal nerve did not induce formation of taste buds. In spite of the extensive studies concerning the taste bud-nerve fiber relationship, insufficient information has been reported about the changes in cellular constitution of taste buds after denervation. The present work was undertaken to study the sequential cellular changes in taste buds after denervation, and, to confirm the trophic effect of the gustatory nerve upon ...

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“…Consistent with previous studies in the hamster (e.g., Oliver and Whitehead, 1992), the number of fungiform buds essentially matched that at the unoperated level 4 weeks after chorda tympani/lingual nerve resection (Table 1). In contrast, within the same survival time period following glossopharyngeal nerve resection, there was a 72% decrease in the number (Table 1) of foliate buds (e.g., compare Naga et al, 1970; Suzuki et al, 1997 in rabbit and rat). Corroborative studies in mature hamster indicate that by 3 months post lesion, glossopharyngeal nerve‐dependent foliate buds exhibit only rare bud remnants (Savoy and Barry, 1992; Barry, Ganchrow, Ganchrow, and Whitehead, unpublished observations).…”

Expression of Mash1 in basal cells of rat circumvallate taste buds is dependent upon gustatory innervation

“…In our observations of in situ hybridization in rat taste buds, Mash1-expressing cells are round cells that lie in the basolateral portion of these structures. The morphology and location of Mash1-expressing cells ¢t the description of basal cells, which are thought to give rise to mature taste bud cells [22]. Furthermore, the expression of Mash1 became undetectable in the epithelium of circumvallate papilla at 2 weeks after the operation, at which time the taste buds have completely disappeared.…”

Apoptosis in mouse taste buds after denervation

“…The morphological preservation, development, and cytodifferentiation of taste buds appears to be dependent on an intact gustatory nerve supply because taste buds degenerate and disappear after gustatory nerve sectioning and regenerate upon regeneration of the nerves (Guth 1945;Farbman 1969;Fujimoto and Murray 1970;Naga et al 1970;Zalewski 1972;Oakley 1974;State and Bowden 1974;Nishimoto et al 1985;Hosley et al 1987;Suzuki and Takeda 1987;Kinnman and Aldskogius 1988;Ganchrow and Ganchrow 1989;Smith et al 1994). During development, the invasion of nerve fibers into the epithelium of circumvallate and fungiform papillae is followed by the appearance of taste buds (Farbman 1965;Nolte and Martini 1992;Takeda et al 1992).…”