Dexamethasone Causes Hypertension in Rats Even Under Chemical Blockade of Peripheral Sympathetic Nerves

Frontiers in Neuroscience

Randy Strong¹  C. S. Sheela Rani¹  Elizabeth Fernandez¹  Carmen Hinojosa-Laborde²  Alejandra D. Benítez-Arciniega³  Alexandra E. Soto-Piña³  Cynthia Franklin⁴  Helmut Gottlieb⁴  Elías Cardoso-Peña⁵ 

[1] Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX, United States;Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States;Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Mexico;Feik School of Pharmacy, University of the Incarnate Word, San Antonio, TX, United States;Unidad de Medicina Familiar 220, Instituto Mexicano del Seguro Social, Mexico City, Mexico;

关键词: dexamethasone;    hypertension;    adrenal medulla;    6-OHDA;    renal denervation;    sympathetic nerves;   

DOI  :  10.3389/fnins.2019.01305

来源: DOAJ

【 摘 要 】

Synthetic glucocorticoids (GCs) are widely used to treat inflammatory conditions. However, chronic use of GCs can lead to hypertension. The cause of this undesired side effect remains unclear. Previously, we developed an in vivo rat model to study the mechanisms underlying hypertension induced by the chronic administration of the potent synthetic GC, dexamethasone (DEX) and found that the catecholamine biosynthetic pathway plays an important role. In the current study, we used this model to investigate the role of the adrenal medulla, renal nerves, and other peripheral sympathetic nerves in DEX-induced hypertension. After 5 days of baseline telemetric recording of mean arterial pressure (MAP) and heart rate (HR), rats were subjected to one of the following treatments: renal denervation (RDNX), adrenal medullectomy (ADMX), 6-hydroxydopamine (6-OHDA, 20 mg/kg, i.p.) to induce chemical sympathectomy, or a combination of ADMX and 6-OHDA. On day 11, the animals received vehicle (VEH) or DEX in drinking water for 7 days, with the latter causing an increase in MAP in control animals. ADMX and RDNX by themselves exacerbated the pressor effect of DEX. In the chemical sympathectomy group, DEX still caused a rise in MAP but the response was lower (ΔMAP of 6-OHDA/DEX < VEH/DEX, p = 0.039). However, when ΔMAP was normalized to day 10, 6-OHDA + DEX did not show any difference from VEH + DEX, certainly not an increase as observed in DEX + ADMX or RDNX groups. This indicates that sympathetic nerves do not modulate the pressor effect of DEX. TH mRNA levels increased in the adrenal medulla in both VEH/DEX (p = 0.009) and 6-OHDA/DEX (p = 0.031) groups. In the 6-OHDA group, DEX also increased plasma levels of norepinephrine (NE) (p = 0.016). Our results suggest that the activation of catecholamine synthetic pathway could be involved in the pressor response to DEX in animals even under chemical sympathectomy with 6-OHDA.

【 授权许可】

Unknown