HUMANIN ABROGATES THE PROAPOPTOTIC ACTION OF TNF-a IN ANTERIOR PITUITARY CELLS

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

San Francisco

Congreso; 95th Annual Meeting of the Endocrine Society; 2013

Humanin (HN) is a 24-amino acid 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 (RN), an homologous peptide of HN in rat, has also a neuroprotective action. In the present study, we evaluated expression and action of HN peptides in anterior pituitary cells from Wistar rats. We determined RN expression in anterior pituitary gland from female (F) and male (M) rats by flow cytometry (FACS). Both the percentage of anterior pituitary cells expressing RN (F: 54.0 ± 16.0 %; M: 85.2 ± 4.1 %, p< 0.05, Student's t test) and RN fluorescence intensity per cell (Geometric mean, Gmean) (F: 20.1 ± 2.4 %; M: 48.9 ± 8.4 %, p< 0.01, Student's t test) in anterior pituitary cells were higher in males than females. In order to evaluate whether gonadal steroids modulate RN expression, we determined this expression in anterior pituitary cells from SHAM-operated and ovariectomized rats (OVX) by FACS. RN Gmean expression was higher in anterior pituitary cells from OVX than cells from SHAM rats (SHAM: 36.5 ± 1.2 %; OVX: 95.7 ± 1.4 %, p< 0.05, Student's t test). We also evaluated the action of HN on anterior pituitary cell apoptosis. Since TNF-alpha induces apoptosis of anterior pituitary cells in an estrogen-dependent manner, we determined the effect of HN on apoptosis of anterior pituitary cells from OVX rats incubated with TNF-alpha in presence of estradiol. The percentage of apoptotic cells was determined by TUNEL assay. HN inhibited the apoptotic effect of TNF-alpha on anterior pituitary cells (C: 1.0 %; TNF-alpha: 9.5 %; HN-TNF-alpha: 0.8 %, p< 0.01, X2) and lactotropes (C: 2.1 %; TNF-alpha: 14.3 %; HN-TNF-alpha: 0.6 %, p< 0.01, X2). Since the expression of RN showed sexual dimorphism and its expression was higher in the anterior pituitary gland from OVX rats, these results suggest that gonadal steroids may be involved in the regulation of RN expression in this gland. Also, our results suggest that HN exerts a cytoprotective role against proapoptotic stimuli in anterior pituitary cells as it was reported in other tissues.