CD8A and neoplasm: To clarify the mechanisms of the anti-tumor effects of the stimulation of D1-receptor-expressing neurons in the nucleus accumbens, we next evaluated the possible changes in the number of leucocytes from the spleen of D1-Cre/hM3Dq mice by specific stimulation of the D1-receptor-expressing neurons in the medial shell region of the nucleus accumbens, and found a significant increase in the number of CD8+ T cells in the spleen following repeated stimulation of D1-receptor-expressing neurons in the medial shell of the nucleus accumbens.