“… Abbreviation s : TH, tyrosine hydroxylase; SN, substantia nigra; OB, olfactory bulb; LC, locus coeruleus; NE, noradrenaline; α-syn, α-synuclein. Reference s : 1 ( Chen et al., 2017 ); 2 ( Wang et al., 2015c , Wang et al., 2015b , Wang et al., 2015a ); 3 ( He et al., 2016b , He et al., 2016a ); 4 ( Fu et al., 2015 ); 5 ( Bao et al., 2018 ); 6 ( Hritcu and Ciobica, 2013 ); 7 ( Hritcu and Gorgan, 2014 ); 8 ( Zheng et al., 2013b , Zheng et al., 2013a ); 9 ( Choi et al., 2009 ); 10 ( Hunter et al., 2007 ); 11 ( Hunter et al., 2017 ); 12 ( Zheng et al., 2013b , Zheng et al., 2013a ); 13 ( Zhang and Xu, 2018 ); 14 ( Khan et al., 2018 ); 15 ( Badshah et al., 2016 ); 16 ( Beier et al., 2017 ), 17 ( Bodea et al., 2014 ), 18 ( Qin et al., 2007 ); 19 ( Qin et al., 2013 ); 20 ( Zheng et al., 2013b , Zheng et al., 2013a ); 21 ( Liu et al., 2008 ); 22 ( Reinert et al., 2014 ); 23 Kelly et al., 2014 ; 24 ( Jiang et al., 2017 ); 25 ( Zheng et al., 2013b , Zheng et al., 2013a ), 26 ( Song et al., 2018 ); 27 ( Chen et al...…”