Objective To explore the effects of pineal gland on the expression of intestinal gene in rats in long summer

and to reveal the material basis of "spleen corresponding to long summer" from the level of transcriptomics. Methods A total of 24 SD rats were randomly divided into a blank group

a sham operation group and an operation group

with 8 rats in each group. Rats in the operation group were ligated the sagittal vein and removed the pineal gland

rats in the sham operation group were ligated the sagittal vein but did not remove the pineal gland

and the blank group was not treated. The rates were raised for 28 days after operation. The general condition of rats in each group and the number of feces and water content were compared. Transcriptome sequencing was used to screen out the significantly differentially expressed genes in the small intestine tissue of the rats in the operation group

and the significant enrichment analysis of GO function and the KEGG pathway of the differential genes were performed. Significant enrichment analysis. Results After excision of rat pineal gland in long summer environment

the diet and activity of the rats in the operation group were decreased

and their body weight were decreased significantly

while the 24-hour defecation amount and fecal water content increased significantly（P<0.01）. Sequencing results showed that there were 64 significant differential genes in the intestinal tissue of the operation group

with 20 up-regulated genes and 44 down-regulated genes. GO functional enrichment analysis indicated that these differentially expressed genes were associated with T cell activation

lymphocyte migration

leukocyte and intercellular adhesion

and adaptive immune response. KEGG pathway enrichment analysis revealed that these genes were associated with cell adhesion molecule-related pathways

natural killer cell-mediated cytotoxicity

IgA-producing intestinal immune network

chemokine signaling pathway

Th1 and Th2 cell differentiation

and NF-κB signaling pathway. Conclusion The pineal gland can inhibit the expression of immune related genes such as Itgb2

Zap70

Cd40

Tnfsf13 b and Icam1 in the intestinal tract

and inhibit multiple immune pathways in the intestinal immune environment

including NF-κB signal path. The pineal gland can promote the body to adapt to the long summer environment and prevent diarrhea

indicating that pineal gland is the key to the "spleen corresponding to long summer".