[The relation between prolactin and lactational anestrus in swine]

Both prolactin and the suckling stimulus are involved in the suppression of LH levels during lactation in the sow. Reduction of the prolactin level by treatment with bromocriptine will result in a significant increase of the LH level, followed by a further significant increase after weaning. The suppression of LH release by the two factors is caused by a blockade at the hypothalamic level. The LH-response to an injection of LHRH is not affected by the presence or absence of prolactin and the suckling stimulus and therefore rules out the pituitary as the primary target organ.