Objective: To investigate the distribution of the substance P (SP) and its receptor in the marginal division (MrD) of rat striatum and to understand the relationship between SP and the learning and memory function of rats.
Methods: Using immunohistochemistry and in situ hybridization techniques, the distribution of SP and its receptor in the MrD was studied, and the relationship between the SP and learning and memory of the MrD was observed by means of SP receptor gene knockout in combination with Y-maze test.
Results: Numerous SP immunopositive fibers and large quantities of SP receptor protein and NK1 mRNA were identified in the MrD of rat striatum. After knockout of the SP receptor gene in the MrD, the ability of learning and memory of the rats was obviously decreased.
Conclusion: SP and its receptor in the MrD may play important roles in the learning and memory function of rat, possibly through the regulation of the neurotransmitters as 5-HT by SP via NK1 receptor.