Immunohistochemical localization of estrogen receptor alpha in the cerebral cortex of the Caiman latirostris (Crocodylia: Alligatoridae)

MORENO PIOVANO G; ROSSETTI MF; DUDIUK C; MUÑOZ-DE-TORO M; LUQUE EH; RAMOS JG

Congreso; II Reunión Conjunta de Sociedades de Neurociencias; 2010

Sociedad Argentina de Neurociencias

In mammals estrogens has been described as endocrine and paracrine modulators of neuronal differentiation and synapse formation. However the functional role of circulating estrogens and the distribution of estrogen receptors (ERs) in the cerebral cortex of reptiles has not been clearly established. Caiman latirostris, is a South American alligator that present temperature (TSD) and hormone dependent sex determination (HSD). By using a polyclonal antibody developed in our lab, we have studied the distribution of ER alpha (ERa) in the medial (MC), dorsal (DC) and lateral cortices (LC) of neonatal (10-day-old) caimans. Three groups of caimans were studied: females and males obtained by temperature sex determination (females and males TSD) and caimans feminized by in ovo administration of estradiol (females HSD). ERa was detected in all cortical areas studied, however only the MC showed sex differences. The intensity of ERa staining was significantly higher in TSD females compared to males (p<0.05). Interestingly, HSD females showed the maximum amount of ERa immunostaining in the MC when compared with both TSD groups (p<0.05). In addition, the level of estradiol was significantly higher in TSD females than TSD males (p<0.05). Double immunostaining showed that ERa is expressed in neural precursor cells (detected by ERa/DCX) and mature neurons (ERa/NeuN). These observations demonstrate that the expression of ERa in the caiman cortex is sexually dimorphic and is present in early stages of neuronal differentiation.