Avaliação eletrofisiológica da ação da guanilina e de uroguanilina em cérebro de ratos

Abstract

Guanylin and uroguanylin are heat-stable peptides isolated and identified from rat intestine and opossum urine, respectively. They control salt and water transport in the kidney and intestine mediated by cGMP. In this study we tried to show the effects of the guanylin-like peptides on EEG-parameters, as well to investigate possible cerebral action mechanisms in the central nervous system. The experiments were performed using anaesthetized male Wistar rats that were placed on the stereotaxic frame for surgery to implant a guide cannula towards to cisterna magna. After 48 hours, the animals were divided in three groups: guanylin (2μg/μl/min) and uroguanylin (2μg/μl/min and 6μg/μl/min), and recived intracisternal infusion by a infusion pump. Another two groups were performed using uroguanylin (2μg/μl/min) and a pretreatment of two Clˉ blockers: niflumic acid and nedocromil sodium. EEG recordings were made throughout the experimental procedure, using a software for spectral activity study and absolute amplitude, starting with the control recording segment, followed by drug infusion segment and finishing with after infusion segment. Guanylin peptide in the rat brain increased the frontal waves amplitude and induced spikes. Uroguanylin induced the same changes more intensively (p<0.05). Niflumic acid didn’t promoted changes, but nedocromil seemed to inhibit the spikes (p<0.05). We propose that guanylin and uroguanilyn EEG effects were caused by Clˉ channels envolvement.