LHRH inactivation by reconstituted horse and fetal bovine sera: assessment by reduction of immunoreactivity and biological activity in pituitary cell cultures

Abstract

Lyophilized horse and fetal bovine sera are commonly incorporated into the growth media used for primary pituitary cell cultures. LHRH degrading activity has been assumed to exist in these preparations but has not actually been demonstrated. During our studies with pituitary cultures, it became necessary to ascertain if LHRH inactivating activity could be demonstrated in these sera. Luteinizing hormone releasing hormone (LHRH) was preincubated in either serum-free medium or medium containing fetal bovine and horse serum. Whether LHRH was lost during these incubations was assessed by diminished immunoreactivity as indicated by radioimmunoassay (RIA) and by diminished biological activity as indicated by reduced release of LH from pituitary cell cultures. Both the RIA and bioassay results indicated LHRH inactivating activity; the loss of LHRH could be prevented by inclusion of bacitracin in the incubations.