*4.1. Animals*

The protocol of all experiments was approved (approval no., KW-2000113-1) on 13 January 2020 by the Ethics Committee of Kangwon National University (Chuncheon, Gangwon, Korea). Animal suffering during the whole experiments was minimized. Sixmonth male gerbils (*Meriones unguiculatus*), weighing 70–80 g, were used. The gerbils originated from Charles River Laboratories International, Inc. (Wilmington, MA, USA). The gerbils were housed in pathogen-free environment under standard condition at a controlled temperature (about 24 ◦C) and humidity (about 60%) on a 12:12 h light–dark cycle.
