Sexually dimorphic expression of receptor-alpha in the cerebral cortex of neonatal Caiman latirostris (Crocodylia: Alligatoridae)

J VARAYOUD; L MONJE; MORENO PIOVANO GUILLERMO; GALOPPO G; EH LUQUE; M MUÑOZ DE TORO; JG RAMOS

GENERAL AND COMPARATIVE ENDOCRINOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2012 vol. 179 p. 205 - 213

0016-6480

In mammals, estrogens have 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 have not been clearly established. Caiman latirostris (C. latirostris) is a South American species that presents temperature-dependent sex determination (TSD). By using immunohistochemistry, we have studied the distribution of ERa in the cerebral cortex of neonatal caimans. We studied brain samples from ten-day-old TSD-females and TSD-males and from female caimans that were administered estradiol during embryonic development (hormone-dependent sex determination, HSD-females). ERa was detected in the medial (MC), dorsal (DC) and lateral (LC) cortices. ERa expression in the MC showed sex-associated differences, being significantly greater in TSD-females compared to TSD-males. Interestingly, the highest ERa expression in the MC was exhibited by HSD-females. In addition, the circulating levels of estradiol were significantly higher in females (both TSD and HSD) than in TSD-males. Double immunostaining showed that ERa is expressed by neural precursor cells (as detected by ERa/doublecortin or ERa/glial fibrillary acidic protein) and mature neurons (ERa/neuron‑specific nuclear protein). Our results demonstrate that the expression of ERa in the neonatal caiman cortex is sexually dimorphic and is present in the early stages of neuronal differentiation.