Possible Association Between DHEA and PKCε in Hepatic Encephalopathy Amelioration: A Pilot Study

Alessandro Di Cerbo; Luca Roncati; Carlotta Marini; Gianluca Carnevale; Manuela Zavatti; Rossella Avallone; Lorenzo Corsi

doi:10.3389/fvets.2021.695375

Possible Association Between DHEA and PKCε in Hepatic Encephalopathy Amelioration: A Pilot Study

Front Vet Sci. 2021 Sep 28:8:695375. doi: 10.3389/fvets.2021.695375. eCollection 2021.

Authors

Alessandro Di Cerbo¹, Luca Roncati², Carlotta Marini¹, Gianluca Carnevale³, Manuela Zavatti⁴, Rossella Avallone⁵, Lorenzo Corsi^{5

6}

Affiliations

¹ School of Biosciences and Veterinary Medicine, University of Camerino, Matelica, Italy.
² Institute of Pathology, University of Modena and Reggio Emilia, Modena, Italy.
³ Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy.
⁴ Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
⁵ Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
⁶ National Institute of Biostructure and Biosystems, Rome, Italy.

Abstract

Objective: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome caused by liver failure and by an impaired neurotransmission and neurological function caused by hyperammonemia (HA). HE, in turn, decreases the phosphorylation of protein kinase C epsilon (PKCε), contributing to the impairment of neuronal functions. Dehydroepiandrosterone (DHEA) exerts a neuroprotective effect by increasing the GABAergic tone through GABA_A receptor stimulation. Therefore, we investigated the protective effect of DHEA in an animal model of HE, and the possible modulation of PKCε expression in different brain area. Methods: Fulminant hepatic failure was induced in 18 male, Sprague-Dawley rats by i.p. administration of 3 g/kg D-galactosamine, and after 30 min, a group of animals received a subcutaneous injection of 25 mg/kg (DHEA) repeated twice a day (3 days). Exploratory behavior and general activity were evaluated 24 h and 48 h after the treatments by the open field test. Then, brain cortex and cerebellum were used for immunoblotting analysis of PKCε level. Results: DHEA administration showed a significant improvement of locomotor activity both 24 and 48 h after D-galactosamine treatment (^**** p < 0.0001) but did not ameliorate liver parenchymal degeneration. Western blot analysis revealed a reduced immunoreactivity of PKCε (^* p < 0.05) following D-galactosamine treatment in rat cortex and cerebellum. After the addition of DHEA, PKCε increased in the cortex in comparison with the D-galactosamine-treated (^*** p < 0.001) and control group (^* p < 0.05), but decreased in the cerebellum (^* p < 0.05) with respect to the control group. PKCε decreased after treatment with NH₄Cl alone and in combination with DHEA in both cerebellum and cortex (^**** p < 0.0001). MTS assay demonstrated the synergistic neurotoxic action of NH₄Cl and glutamate pretreatment in cerebellum and cortex along with an increased cell survival after DHEA pretreatment, which was significant only in the cerebellum (^* p < 0.05). Conclusion: An association between the DHEA-mediated increase of PKCε expression and the improvement of comatose symptoms was observed. PKCε activation and expression in the brain could inhibit GABA-ergic tone counteracting HE symptoms. In addition, DHEA seemed to ameliorate the symptoms of HE and to increase the expression of PKCε in cortex and cerebellum.

Keywords: DHEA; animal model; hepatic encephalopathy; hyperammonemia; protein kinase C (PKC).