Pituitary Activin System during Postnatal Development

DÍAZ -TORGA GRACIELA; ERIKA FARAONI; DANIEL PISERA; ALEJANDRA ABELEDO MACHADO; JIMENA FERRARIS; M ANDREA CAMILLETTI

Chicago

Congreso; ENDO 2018; 2018

Endocrine Society

Activin(Act) is a knowninhibitor of lactotroph, somatotroph and gonadotrophfunctions. Acts are homodimers of βchains; A and B, giving rise to Act A (βA-βA), B (βB-βB) or AB (βA-βB). Acts bind to receptors type II (ActRII or ActRIIB) and type I (ActRI/ALK4), inducing direct phosphorylation of SMAD2/3 and leading to target genes transcription. In lactotrophs, activin-dependent translocationof pSMAD2/3-SMAD4 complex to the nucleus depends on the presenceof Menin (MEN 1).On the other hand,follistatin (FST)is anAct-binding protein that bio-neutralizes and thereby modulatesActs actions. The aim of the present work was to study the ontogeny of the pituitaryAct system, in association with lactotroph function, in male and female Sprague Dawley rats at different postnatal ages: 11, 23 and 45 days. Adult females were used atdiestrus. The activin system components expressionwas evaluated by qRT-PCR and western blot.Serum prolactin (PRL) levels weremeasured by RIA andPRL inpituitaries homogenates was measuredby western blot. Statistical analysis: Two-Way ANOVA, followed by post hoc Tukey test.We found interesting gender and age differences in the expression of the Act System during pituitary ontogeny. In females, but not in males,mRNA levels and protein expression of most of the components evaluated (βA, βB, ActRII, ActRIIB, FST and Menin) werehigher in 11 days old pups and decreased at older ages, showing an inverse correlation with PRL levels andthe expression of lactotroph specific transcription factor,Pit1.Also, in 11 days pups, pituitary mRNA expression of all components was found significantly increased in female compared to male (p