Antiapoptotic action of Humanin in anterior pituitary cells from male rats

GOTTARDO FLORENCIA; MAGRI MARIA LAURA; ZÁRATE SANDRA; FERRARIS JIMENA; EIJO GUADALUPE; MORENO AYALA MARIELA; CANDOLFI MARIANELA; PISERA D; JAITA GABRIELA; SEILICOVICH ADRIANA

CHICAGO

Congreso; 96º Annual Meeting of the Endocrine Society/16º International Congress of Endocrinology; 2014

Humanin (HN) is a 24-aminoacid peptide originally isolated from a cDNA library of surviving neurons of familial Alzheimer´s disease. HN has a cytoprotective action in several cell types such as neurons, lymphocytes and testicular germ cells. Rattin (HNr), an homologous peptide of HN in rat, has also a neuroprotective action. In the present study, we evaluated the action of HN on apoptosis of anterior pituitary cells from male Wistar rats. Since TNF-α induces apoptosis of anterior pituitary cells in an androgen-dependent manner, we determined the effect of HN on apoptosis of anterior pituitary cells from gonadectomized (GNX) rats incubated with TNF-α (50 ng/ml) in the presence of dihydrotestosterone (DHT, 10-8M). The percentage of apoptotic cells was determined by TUNEL assay and pituitary subpopulations were identified by immunofluorescence. HN (5 μg/ml) inhibited the apoptotic effect of TNF-α on anterior pituitary cells (C: 0.7 %; TNF-α: 3.0 %; HN: 1.0 %; HNTNF-α: 0.9 %, p< 0.05, χ2), lactotropes (C: 1.0 %; TNF-α: 3.3 %; HN: 1.3 %; HN-TNF-α: 1.2 %, p< 0.05, χ2) and somatotropes (C: 2.0 %; TNF-α: 5.9 %; HN: 2.3% HN-TNF-α: 1.7 %, p< 0.05, χ2). We have previously shown that HNr expression in the anterior pituitary gland from male rats is higher than in females. In order to evaluate whether gonadal steroids modulate HNr expression in anterior pituitary cells from male rats, we evaluated the expression of HNr in pituitary cells from GNX rats incubated with 17β-estradiol (E2) or DHT by flow citometry (FACS). E2 decreased the percentage of anterior pituitary cells expressing HNr (C: 78.8 ± 10.5 %; E2: 44.7 ± 3.5 %, p< 0.05, Student´s t test) whereas DHT had no effect on this expression. Our results suggest that HN exerts an antiapoptotic action against proapoptotic stimuli in anterior pituitary cells and could be involved in tissue homeostasis in this gland. Alterations in HNr expression may affect cell turnover and play a role in the development of anterior pituitary tumors.