Co-occurrence of immunoreactive corticotrop in-like and α-melanotropin-like material in pituitary cells: Differences between young and adult rats

摘要: Abstract We examined to which extent adrenocorticotropin (ACTH)-like substances are cleavable into α-melanotropin (MSH)-like material by application of exogenous enzymes on pituitary sections prior immunocytochemical stainings. In pro-opiomelanocortin (POMC) cells the anterior lobe from developing rats (1 21 postnatal days) at least one two contained α-MSH-like immunoreactivity besides ACTH-like immunostaining. Pretreatment these tissue with tryptic enhanced remarkably contrast, α-MSH-lik was almost not detectable in lobes adult rats, also after treatment enzymes. After adrenalectomy (ax) POMC behaved similarly: a few days operation all ACTH α-MSH immunostaining, whereas more than weeks immunostaining nearly absent, contrast young and guinea pig pituitaries prevented These observations consistent assumption that occurrence ACTH- rat is regulated protection mechanism against proteolytic cleavage sequence appears delay differentiating maturing cells.