Systemic administration of insulin and epinephrine modulate the gabaa recruitment in chicks with different emotional reactivity

TOLEDO C. Y SALVATIERRA N.A.

Huerta Grande, Córdoba

Congreso; First Joint Meeting of the Argentine Society for Neuroscience (SAN) and the Argentine Workshop in Neuroscience (TAN); 2009

Systemic administration of insulin and epinephrine modulate the GABAA recruitment in chicks with different emotional reactivity. Toledo C. M. y Salvatierra N.A. Dpto. Química. Facultad de Ciencias Exactas, Físicas y Naturales, UNC. Av. Vélez Sarsfield 1611-X5016GCA-Córdoba. e-mail: toledo_caro@hotmail.com Many studies have shown that neurotransmitters systems, excitatory and inhibitory as the GABAergic system, are responsible to evaluate different stressful events. Postsynaptic density, cellular surface expression and synaptic traffic of GABAAR can be modulated by extracellular signals such as insulin and epinephrine. Our previous findings, in day-old-chicks, show different behavioral, pharmacological and neurochemical responses to novelty between individuals among the same population. Thus, this different emotional reactivity was used to categorize birds with different degrees of fear and/or anxiety and they were termed as high latency (HL), moderate latency (ML) or low latency (LL). Moreover, systemic administration of insulin and different doses of epinephrine increase GABAAR in synaptosomes from control (not stressed) chicks and stressed ones, respectively. In this work, a Partial Water Immersion induced an increase of GABAAR in all subpopulations categorized. However, control chicks, from ML and HL subpopulations, showed different susceptibility to an insulin injection (2.5 IU/mg). However, the insulin effect was not additive to the stress-induced increase suggesting that both effects occur through similar mechanisms. Co-administration of insulin and epinephrine (0.25 mg/kg) increased the receptor density in HL group compared to insulin alone. No significant increase in 0.5 mg/kg of epinephrine was observed, suggesting that epinephrine action depends on, and adds to the increase induced by insulin alone possibly by increasing the synaptic strength in subpopulations with higher fearfulness.