Involvement of splenocytes in the control of corpus luteum function in the rat.

We previously found that splenectomy caused a 1-day delay in ovulation in cycling rats. In the present study, the role of the spleen or splenocytes in corpus luteum function was investigated by comparing long-term splenectomized (SPX) rats with intact controls. When the rats were cervically stimulated on the day of proestrus, both SPX and control rats showed prolonged diestrus for 16 days associated with an increase in serum progesterone (P). However, in SPX rats, 20 alpha-dihydroprogesterone (20 alpha-OHP) concentrations were double those of controls throughout the period of pseudopregnancy. The concentration of total progestin (P plus 20 alpha-OHP) was also higher in SPX rats. All of these phenomena were normalized by injecting the animals with splenocytes. Taken together with our previous findings, these results indicate that splenocytes are involved in the control of ovarian function.