Morphological and functional changes of taste buds on the soft palate during development.

对大鼠出生后发育过程中软腭和舌头上的味蕾进行定量检查发现，出生时软腭上有200个味蕾，与3周龄时一样多，但在50个味蕾上观察到有味觉孔。相反，在未观察到味觉孔的情况下，新生大鼠舌前真菌状乳头中存在的味蕾少于100个，在出生后的4周内，味蕾数量增加，最多可达200个。大鼠和仓鼠GSP的电生理记录表明，软腭上甜味物质的味觉刺激会在GSP神经上产生强烈的反应。大鼠GSP不仅对糖，而且对各种氨基酸也产生了强烈的反应。在大鼠鼓室索中，l -氨基酸比d -形式更具刺激性，而GSP对氨基酸的反应比对映体更好。此外，在仓鼠的双侧GSP和/或CT神经横断导致对蔗糖的条件厌恶的显著减少。切片效果顺序为GSP + CT > GSP (] SY.gtoreq。[) CT > sham。考虑到软腭上分布着大量的味蕾，并且对包括多种氨基酸在内的甜物质具有强烈的反应性，软腭的味觉功能应该在出生后发育早期对牛奶的摄入起着重要的作用。

Quantitative examination of taste buds on the soft palate and the tongue in the rat during the postnatal development revealed that there exist 200 taste buds on the soft palate at birth as many as in 3-week-old although taste pore were observed in 50 taste buds. On the contrary, less than 100 taste buds, without observation of taste pore, existed in fungiform papillae on the anterior tongue in new born rats, and the number of taste buds postnatally increased during 4 weeks, reached to the maximum of 200. Electrophysiological recordings from the GSP in the rat and hamster showed that taste stimulation with sweet substances on the sofr palate produces robust responses on the GSP nerve. The rat GSP produced robust responses not only to sugars but also to various amino acids. In the rat chorda tympani, L-amino acids are more stimulatory than the D-forms, while the GSP responds better to Damino acids compared to the enantiomers. Also, bilateral transection of the GSP and/or CT nerves in the hamster resulted in a significant reduction of the conditioned taste aversion for sucrose. The order of the sectioning effects was GSP + CT > GSP (〕SY.gtoreq.〔) CT > sham. Considering numeral taste buds distributed on the soft palate, and the strong responsiveness for sweet substances including many amino acids, gustatory function of the soft palate should play an important role on the ingestion of milk during early development in postnatal stage.