Cardiovascular responses to sciatic nerve stimulation are blocked by paratrigeminal nucleus lesion

The paratrigeminal nucleus (Pa5) receives primary sensory inputs from the vagus, glossopharyngeal, and trigeminal nerves and has efferent projections to the nucleus of the solitary tract (NTS), rostroventrolateral reticular nucleus (RVL), as well as to the nucleus ambiguus (Amb), lateral reticular (LRt), parabrachial (PB) and ventral posteromedial thalamic (VPM) nuclei. suggesting that it may play a significant role in cardiovascular responses to nociceptive stimuli. the aim of the present study was to evaluate the effects of unilateral lesions of the Pas on cardiovascular alterations induced by afferent somatic sensory nerve stimulation (SNS), also known as the somatosympathetic reflex (SSR). Cardiovascular responses were recorded in rats following either sham operation or unilateral lesions of the Pas with ibotenic acid. Mean arterial blood pressure (MAP) increased after SNS, which in sham-lesioned animals raised from 95 +/- 4 to 115 +/- 2 mmHg. Ipsilateral Pas lesion did not significantly reduce the pressor response to SNS (from 91 +/- 7 to 107 +/- 4 mmHg increase of baseline MAP). On the other hand, contralateral Pa5 lesion significantly reduced the response to SNS (from 99 +/- 5 to 104 +/- 2 mmHg). Sciatic nerve stimulation did not alter heart rate (HR) neither did ipsi- or contralateral Pas lesion HR baseline response level. These findings support a crucial role for the Pas in cardiovascular regulation, by relaying SSR input evoked by peripheral nerve stimulation. (C) 2002 Elsevier Science B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Escola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilUFSC, Dept Pharmacol, Florianopolis, SC, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilWeb of Scienc