Intracerebroventricular injection of liposome‐entrapped GABA attenuates the renal sympathetic nerve activity response evoked by central administration of bicuculline in spontaneously hypertensive rats

Abstract

Liposomes are lipid vesicles that allow a sustained release of entrapped substances. GABA is the most prevalent inhibitory neurotransmitter in the central nervous system. In this study we tested the efficacy of liposome‐entrapped GABA (GL) in attenuating the cardiovascular response evoked by intracerebroventricular (icv) administration of GABAA antagonist bicuculline methiodide (BMI). Liposomes were prepared by the freeze‐thawing method followed by extrusion (200‐nm final vesicle diameter). Under tribromoethanol anesthesia (250 mg/Kg i.p.), guide cannula was implanted into the lateral ventricle of spontaneously hypertensive rats (SHR). In two groups of animals (n=5–6), GL or empty liposomes (EL, 0.9% NaCl) were injected icv 48 hours before the GABAA antagonist (BMI, 0.5 nmol/2μL). The icv injection of BMI increased the renal sympathetic nerve activity in EL group, this effect was greatly attenuated in GL group (22 ± 6 vs. 0.8 ± 6 %, P = 0.032). Conversely, BMI injection did not change HR and MAP in both groups. Current data extends our previous findings suggesting that liposome‐entrapped GABA is a promising tool for long‐term intervention in central nervous system. Support: INCT NanoBiofar/CNPq/FAPEMIG