  The out-of-plane resistivity ($\rho_c$) and magnetoresistivity (MR) are
studied in antiferromangetic (AF) $Nd_{2-x}Ce_xCuO_{4}$ single crystals, which
have three types of noncollinear antiferromangetic spin structures. The
apparent signatures are observed in $\rho_c(T)$ measured at the zero-field and
14 T at the spin structure transitions, giving a definite evidence for the
itinerant electrons directly coupled to the localized spins. One of striking
feature is an anisotropy of the MR with a fourfold symmetry upon rotating the
external field (B) within ab plane in the different phases, while twofold
symmetry at spin reorientation transition temperatures. The intriguing thermal
hysteresis in $\rho_c(T,B)$ and magnetic hysteresis in MR are observed at spin
reorientation transition temperatures.
