[Involvement of cerebellohypothalamic projections in the modulation of lymphocyte function by cerebellar fastigial...

To explore the effect of cerebellar fastigial nuclei (FN)on lymphocyte function and the pathway mediating the effect.

Kainic acid (KA) was microinjected into bilateral FN of rats to destroy neuronal bodies in the FN. On the eighth day after the surgery, lymphocyte percentage in the peripheral blood and level of sheep red blood cell(SRBC)-specific IgM antibody in the serum were measured by using blood corpuscle counter and enzyme-linked immunosorbent assay (ELISA), respectively.A technology of electrolytic lesion was used to destroy the projections of cerebellar FN neurons to hypothalamus in decussation of superior cerebellar peduncle(xscp).

On the eighth day after the microinjection of KA into the bilateral FN of rats, the Nissl-stained neuronal bodies in the FN disappeared and glia could proliferated within the damaged FN. In the nuclei close to FN, the interposed nuclei and the dentate nuclei, Nissl-stained neurons still could be seen. On the control cerebellar sections, in which FN was infused with saline, we could see the normal Nissl-stained neurons in the FN and the other two nuclei.On day 8 following the effective FN lesions, both the lymphocyte percentage in the peripheral blood and the level of anti-SRBC IgM antibody in the serum were significantly increased in comparison with those of control rats infused with saline in the FN. On the eighth day after electrolytic lesion of the fibres in xscp, the FN-hypothalamic projections were damaged and there were no visible BDA-positive endings in hypothalamus. Meanwhile, both the lymphocyte percentage in the peripheral blood and the level of anti-SRBC IgM antibody in the serum were remarkably enhanced relative to those of control rats with sham lesion of xscp.

The electrolytic lesion of the FN-hypothalamic projections in xscp causes an enhancement of lymphocyte function similar to that of KA lesions of neuronal soma in the FN. These findings suggest that the cerebellohypothalamic projections participate in mediating the modulation of lymphocyte function by the cerebellum.