RESUMO
BACKGROUND: Salt-sensitive hypertension in humans and experimental models is associated with higher plasma and cerebrospinal fluid sodium chloride (NaCl) concentrations. Changes in extracellular NaCl concentrations are sensed by specialized neurons in the organum vasculosum of the lamina terminalis (OVLT). Stimulation of OVLT neurons increases sympathetic nerve activity (SNA) and arterial blood pressure (ABP), whereas chronic activation produces hypertension. Therefore, the present study tested whether OVLT neuronal activity was elevated and contributed to SNA and ABP in salt-sensitive hypertension. METHODS: Male Dahl salt-sensitive (Dahl S) and Dahl salt-resistant (Dahl R) rats were fed 0.1% or 4.0% NaCl diets for 3 to 4 weeks and used for single-unit recordings of OVLT neurons or simultaneous recording of multiple sympathetic nerves during pharmacological inhibition of the OVLT. RESULTS: Plasma and cerebrospinal fluid Na+ and Cl- concentrations were higher in Dahl S rats fed 4% versus 0.1% or Dahl R rats fed either diet. In vivo single-unit recordings revealed a significantly higher discharge of NaCl-responsive OVLT neurons in Dahl S rats fed 4% versus 0.1% or Dahl R rats. Interestingly, intracarotid infusion of hypertonic NaCl evoked greater increases in OVLT neuronal discharge of Dahl S versus Dahl R rats regardless of NaCl diet. The activity of non-NaCl-responsive OVLT neurons was not different across strain or diets. Finally, inhibition of OVLT neurons by local injection of the gamma-aminobutyric acid agonist muscimol produced a greater decrease in renal SNA, splanchnic SNA, and ABP of Dahl S rats fed 4% versus 0.1% or Dahl R rats. CONCLUSIONS: A high salt diet activates NaCl-responsive OVLT neurons to increase SNA and ABP in salt-sensitive hypertension.
Assuntos
Hipertensão , Organum Vasculosum , Ratos , Animais , Humanos , Masculino , Cloreto de Sódio/farmacologia , Ratos Sprague-Dawley , Alta do Paciente , Ratos Endogâmicos Dahl , Cloreto de Sódio na Dieta , Hipotálamo , Pressão Sanguínea/fisiologiaRESUMO
Se presenta una breve revisión de órgano vascular de la lámina terminal (organum vasculosum laminae terminalis) y el nervio olfatorio, el primero un elemento neuroanatómico hipotalámico relacionado con la producción de hormona antidiurética y su asociación como una vía potencial de invasión del COVID-19 al sistema nervioso central, afectando la regulación fisiológica de liberación de hormonas relacionadas con la homeostásis del sodio. También se vincula el neurotropismo de este virus al asociarse con el nervio olfatorio, una evaginación del cerebro en la que se altera su funcionalidad por generación de disosmia entre otras características neurosemiológicas. Se plantea la necesidad de advertir a los profesionales de la salud en general y a los neurólogos en especial, sobre las potenciales alteraciones neurológicas relacionadas con esta pandemia antes y después del contagio de este virus e implementar una prueba olfatoria rápida con ácido acético, incluso antes de otras valoraciones como hipertérmia, tos y cefalalgia.