Central mechanism of the cardiovascular responses caused by L-proline microinjected into the paraventricular nucleus of the hypothalamus in unanesthetized rats

Autor(es)

Lopes-Azevedo, Silvana ; Busnardo, Cristiane ; Aguiar Correa, Fernando Morgan

• Tipo de documento: Artigo Científico
• Fonte: Brain Research; v. 1652, p. 43-52, DEC 1 2016.
• Citações Web of Science: 0

Resumo

Previously, we reported that microinjection of L-proline (L-Pro) into the paraventricular nucleus of the hypothalamus (PVN) caused vasopressin-mediated pressor responses in unanesthetized rats. In the present study, we report on the central mechanisms involved in the mediation of the cardiovascular effects caused by the microinjection of L-Pro into the PVN. Microinjection of increasing doses of L-Pro (3-100 nmol/100 nL) into the PVN caused dose-related pressor and bradycardic responses. No cardiovascular responses were observed after the microinjection of equimolar doses (33nmol/100nL) of its isomer D-Proline (D-Pro) or Mannitol. The PVN pretreatment with either a selective non-NMDA (NBQX) or selective NMDA (LY235959 or DL-AP7) glutamate receptor antagonists blocked the cardiovascular response to L-Pro (33 nmol/100 nL). The dose-effect curve for the pretreatment with increasing doses of LY235959 was located at the left in relation to the curves for NBQX and DL-AP7, showing that LY235959 is more potent than NBQX, which is more potent than DL-AP7 in inhibiting the cardiovascular response to L-Pro. The cardiovascular response to the microinjection of L-Pro into the PVN was not affected by local pretreatment with N-omega-Propyl-L-arginine (N-Propyl), a selective inhibitor of the neuronal nitric oxide synthase (nNOS), suggesting that NO does not mediate the responses to L-Pro in the PVN. In conclusion, the results suggest that ionotropic receptors in the PVN, blocked by both NMDA and non-NMDA receptor antagonists, mediate the pressor response to L-Pro that results from activation of PVN vasopressinergic magnocellular neurons and vasopressin release into the systemic circulation. (AU)

• Processo FAPESP: 14/22228-6 - Função do núcleo supra-óptico do hipotálamo nas respostas cardiovascular e neuroendócrina observadas em ratos submetidos ao estresse por restrição
• Beneficiário: Silvana Lopes Azevedo
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 10/11303-6 - Estudo dos efeitos cardiovasculares causados pela microinjeção de L-prolina em núcleos hipotalâmicos de ratos não anestesiados
• Beneficiário: Silvana Lopes Azevedo
• Modalidade de apoio: Bolsas no Brasil - Doutorado