Combination antiretroviral therapy (cART)-induced hippocampal disorders: Highlights on therapeutic potential of Naringenin and Quercetin

Abstract

Introduction: In spite of the multiple benefits of combination antiretroviral therapy (cART) on HIV positive patients, prolonged usage has been reported to exacerbate oxidative stress, and induce neurological and cognitive dysfunction, thus, the need to search for an adjuvant therapy to ameliorate the oxidative and improve treatment adherence with better virological outcome. This study aimed at determining the potential therapeutic effects of Quercetin and Naringenin on cART-induced cyto-architectural, neuro-behavioral and immunohistochemical changes in the hippocampus of the adult Wister rats.

Materials and methods: The animals were grouped as follows: Control, DMSO, 24 mg/kg cART (Tenovovir 300 mg, Lamivudine 300 mg and Efavirenz 600 mg), 50 mg/kg Naringenin, 50 mg/kg Quercetin, cART + Naringenin, cART + Quercetin were administered orally for 8 weeks. At the end of administration, neurobehavioural test was conducted, animals were euthanized and hippocampus was processed for oxidative stress markers, histology, TNF-α, and Monoamine oxidase-B expression.

Results: At the end of 8 weeks of administration, 24 mg/kg cART decreased superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and increased Malondialdehyde (MDA). Whereas, 50 mg/kg quercetin, and 50 mg/kg Naringenin decreased the oxidative stress (increased SOD, CAT, GSH, and reduced MDA) induced by cART (reduced SOD, CAT, GSH, and increased MDA). In addition, hematoxylin and eosin stained hippocampus showed that quercetin and naringenin prevented neurodegenerative changes (marked cytoplasmic shrinkage and several pyknotic nuclei in the dentate gyrus and cornus ammonis regions) in cART-treated rats. Furthermore, immunohistochemical studies revealed that quercetin and naringenin attenuates cART-induced upregulation of monoamine oxidase-B (MAO-B) expression. Likewise, from the Morris water maze neurobehavioral studies, naringenin and quercetin also ameliorated cART-induced memory impairments (initial spatial memory, reversal spatial memory and probe tests).

Conclusion: This study shows that Naringenin and Quercetin have a good potential in reversing cART-induced hippocampal disorders in Wistar rats.

Keywords: CA/Q, 24 mg/kg combination antiretroviral therapy + 50 mg Quercetin; CAT, catalase; DMSO, dimethyl sulfoxide; DTA, ethylenediaminetetraacetic acid; ELISA, enzyme-linked immunosorbent assay; GSH, reduced glutathione; HCL, hydrochloric acidE; Hippocampus; MAO-B, monoamine oxidase B; MDA, malondialdehyde; Nar, naringenin; Naringenin; Neurodegeneration; Oxidative stress; Quer, quercetin; Quercetin; ROS, reactive oxygen species; SOD, superoxide dismutase; TBA, thiobarbituric acid; TNFα, tumor necrosis factor alpha; cA/N, 24 mg/kg combination antiretroviral therapy + 50 mg Naringenin; cART; cART, combination antiretroviral therapy.

Fig. 1

Showing Oxidative stress markers and Tumor necrosis factor alpha (TNFα). *p < 0.05 compared to control; ^αp < 0.05 compared to cART; ^ααp < 0.001 compared to cART, ᶞp < 0.05, ᶞᶞp < 0.001, ᶞᶞᶞp < 0.0001 compared to DMSO (n=5). Figures are represented as mean ± SD.

Fig. 2

Dentate gyrus in the hippocampus of rats. Groups Control, Nar, Quer, cA/N, and cA/Q show normal histology with very few marked pyknotic neurons (red arrows). DMSO and cART show marked shrinkage of the cytoplasm, pyknotic nuclei and ferrugination of neurons (red arrows) (n = 5).

Fig. 3

Cornu ammonis area 3 (CA3) of hippocampus. Control: showing normal neurons (black arrows); DMSO: presence of pyknotic nuclei (red arrows). cART: multiple pyknotic nuclei and increased mineralization in soma bodies (red arrows); Nar, Quer, cA/N and cA/Q show normal cytoarchitecture with very few pyknotic nuclei (n = 5).

Fig. 4

Immunohistochemistry of Monoamine oxidase B (MAO- B) expression seen in the brown stains x400 (left), x1000 (right) (n = 5).

Fig. 5

(a) quantification of pyknotic neurons (b) Quantification of Immunohistochemistry of Monoamine oxidase B (MAO- B) expression. Values are represented as mean ± SD. *p < 0.05, **p < 0.001, ***p < 0.0001 compared to control; ^αp < 0.05, ^ααp < 0.001, ^αααp < 0.0001 compared to cART, ᶞp < 0.05, ᶞᶞp < 0.001, ᶞᶞᶞp < 0.0001 compared to DMSO.

Fig. 6

Neurobehavioral studies: Morris water maze test. *p < 0.05, **p < 0.001, ***p < 0.0001 compared to control; ^αp < 0.05, ^ααp < 0.001, ^αααp < 0.0001 compared to cART, ᶞp < 0.05, ᶞᶞp < 0.001, ᶞᶞᶞp < 0.0001 compared to DMSO (n=5). Figures are represented as mean ± SD.