Central nucleos of amygdale, locus coerulues and paraventricular nucleus of dolphin´s brain: where and why?

Abstract

The brain is still nowadays a great mystery for researchers. There is a great lack of information concerning neuroanatomy of cetaceans. Based on our previous results {Arbe!o, 2007; Herraéz et al., 2007). we have intended to investigate those nuclei related with acute catecholaminergic stress-response. Massive catecholamine's liberation from the adrenal glands has been reported in alive stranded cetaceans, as a capture response (alarm reaction) (Cowan and Curry, 2008). But what could trigger such a dramatic reactíon? We focused on three nuclei that are known to be involved with the alarm reactíon: central nucleus of the amygdaloid complex (NCA), locus coeruleus {LC) and paraventricular nucleus (PVN). Serial 50 µm sections of the amygdaloid complex, hypothalamus and brainstem (at the leve! of the inferior colliculus) were made using a sliding-microtome with a cooling unit. Sections were later stained for Nissl substance with thionin and immunocytochemícally stained for Calbindin (NCA), Tyrosine Hydroxylase (LC) and Vasopressin (PVN) using the free-floating technique. This is a prelirninary study; the final goal of our research is to obtain a microscopical description of these nuclei, in arder to later detect the expression of sorne acute stress biomarkers like c-fos and HSP70 {Heat Shock Protein 70).