Intracerebroventricular injection of Tityustoxin increases the cardiovascular parameters and renal sympathetic nerve activity (686.18)

The scorpion envenoming is an important public health problem in tropical and subtropical countries. Despite, clinical studies address the high sensitivity of the central nervous system to Titystoxin (TsTX) action, mainly in infants, few studies focus on the central action of the scorpion toxins. Because of this we aimed to assess if the cardiovascular parameters and renal sympathetic nerve activity (RSNA) could be altered by a central injection of a very low dose of TsTX (0.116µg), which is more than 20,000 times less concentrated than those used in peripheral experiments. Urethane anesthetized wistar male rats (n=5) were submitted to: 1) tracheostomy to airway maintenance, 2) arterial and vein femoral cannulation to measure the cardiovascular parameters and drugs infusions, 3) location of the left lateral ventricle to PBS and TsTX injection (1μl) and 4) isolation of renal nerve to measure the RSNA. Mean arterial pressure (MAP), Heart Rate (HR) and RSNA records were done before (20 min for baseline and PBS periods) and after TsTX injection (60 min). TsTX period was divided in: beginning (B), midlle (M) and final (F). Methods were approved by Ethical Committee (CEUA/UFOP:2011/46;2013/49). Results were expressed as mean ± SEM. Naturally, PBS did not changes the parameters. But, TsTX increased the MAP(Δ):(B)= 15±7, (M)=21±9, (F)= 21±12mmHg; p =0,0005; HR(Δ): (B)=45±19, (M)=74±22, (F)= 82± 25 bpm; p=0,0039 and (ΔRSNA,% of baseline: (B)=101±18; (M)=187±26, (F)= 254±38; p< 0,0001. These results indicate a high sensitivity of blood pressure and HR control nuclei and the huge RSNA responsiveness to the central action of a very low dose of TsTX. Grant Funding Source : Supported by UFOP, CAPES, FAPEMIG and CNPq