Abstract
In the present study, the two types of the inferior alveolar nerve (IAN) injured models were developed as follows; the IAN transection model (T model) and the IAN removed model in which a part of the IAN was taken out in 1mm length (R model). The time-course changes in GAP-43 expression of the trigeminal ganglion (TRG) neurons and the jaw opening reflex (JOR) occurrence were studied in the rats with IAN injury. The following results were obtained.1. The strong expression of the GAP-43 was observed in the T model at 3 to 60 days after IAN transection. On the other hand, the GAP-43 expression was increased at 3 to 30 days and decreased after that in the R model.2. The JOR could not be elicited by IAN stimulation until 7 days after IAN transection and could be observed in the 40% of the T models at 14 days and 100% of them at 60 days after that.3. JOR threshold was gradually decreased in the T model after IAN injury.4. The number of large diameter TRG neurons with GAP-43 positivity was significantly smaller in T and R models at 7 to 60 days after IAN injury as compared with that of naive. 5. The number of GAP-43 positive small diameter TRG neurons was significantly larger in T and R models after IAN injury as compared with naive rats except that in R model at 7 days after nerve injury. The number of them was gradually decreased both in T and R models. These results suggest that the regeneration mechanism was different on the basis of the type of nerve injury and the small diameter primary afferent neurons would be dominantly involved in the regeneration of the injured nerve. [Jpn J Physiol 54 Suppl:S173 (2004)]
