title: Sexually dimorphic expression of receptor-alpha in the cerebral cortex of neonatal Caiman latirostris (Crocodylia: Alligatoridae).
abstract: 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 ERα 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). ERα was detected in the medial (MC), dorsal (DC) and lateral (LC) cortices. ERα expression in the MC showed sex-associated differences, being significantly greater in TSD-females compared to TSD-males. Interestingly, the highest ERα 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 ERα is expressed by neural precursor cells (as detected by ERα/doublecortin or ERα/glial fibrillary acidic protein) and mature neurons (ERα/neuron-specific nuclear protein). Our results demonstrate that the expression of ERα in the neonatal caiman cortex is sexually dimorphic and is present in the early stages of neuronal differentiation.
authors.affiliation: Laboratorio de Endocrinología y Tumores Hormonodependientes, School of Biochemistry and Biological Sciences, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Jorgelina
authors.initials: J
authors.lastname: Varayoud
authors.forename: Lucas
authors.initials: L
authors.lastname: Monje
authors.forename: Guillermo Samuel
authors.initials: GS
authors.lastname: Moreno-Piovano
authors.forename: Germán Hugo
authors.initials: GH
authors.lastname: Galoppo
authors.forename: Enrique Hugo
authors.initials: EH
authors.lastname: Luque
authors.forename: Mónica
authors.initials: M
authors.lastname: Muñoz-de-Toro
authors.forename: Jorge Guillermo
authors.initials: JG
authors.lastname: Ramos
mesh_terms: D000489:Alligators and Crocodiles / Q000196:embryology / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000187:drug effects; D004958:Estradiol / Q000097:blood / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000096:biosynthesis* / Q000187:drug effects; D005260:Female; D008297:Male; D009474:Neurons / Q000166:cytology / Q000502:physiology; D012727:Sex Characteristics; D019849:Sex Determination Processes / Q000187:drug effects*; D013696:Temperature
chemical_list: D047628:Estrogen Receptor alpha; D004958:Estradiol