Possible interaction of luteinizing hormone-releasing factor with other hypothalamic releasing factors at the level of the adenohypophysis.

Abstract

SUMMARY Anterior pituitary halves from adult male rats were incubated in vitro for 6 hr. in tissue culture Medium 199. Luteinizing hormone (LH) released from these glands under the influence of purified preparations of growth hormone-releasing factor (GH-RF), growth hormone-inhibiting factor (GH-IF), corticotrophin-releasing factor (C-RF) and follicle-stimulating hormone-releasing factor (FSH-RF) was determined by the ovarian ascorbic acid depletion (OAAD) assay. The effects of these factors, both alone and together with purified luteinizing hormone-releasing factor (LH-RF), were examined and compared with the response to purified LH-RF alone. While LH-RF consistently produced significant increases in LH release, none of the other factors did so, although FSH-RF showed some indication of LH-releasing activity, probably due to incomplete separation from LH-RF on the Sephadex gel filtration column used for purification. The LH released in response to LH-RF was not affected by the presence of any of the other factors. An apparent slight augmenting effect of FSH-RF could be accounted for by its contamination with LH-RF. The results are discussed in relation to the physiological mechanisms concerned in modifying LH release from the adenohypophysis.