Implanted Vpr and Vpr-derived peptides exert differential effects in vivo. Nissl-stain preparations of ipsilateral basal ganglia (A-D) displayed more neurons in animals implanted with PBS (A) or ΔVpr77Q-HAD (D) compared with full length Vpr (B) or ΔVpr77R-ND (C) implanted animals. Iba-1 immunoreactivity was minimally detected in animals implanted with PBS (E) or ΔVpr77Q-HAD (H) compared with full length Vpr (F) or ΔVpr77R-ND (G) implanted animals, which showed numerous microglia. GFAP immunoreactivity was increased in animals implanted with PBS (I) or ΔVpr77Q-HAD (L) compared with full length Vpr (J) or ΔVpr77R-ND (K) implanted animals. Ipsiversive rotary behaviour fraction (relative to the total number of rotations) did not differ significantly between groups at day 14 post-implant (M) but at day 28 both full length and ΔVpr77R-ND (N) implanted animals showed great ipsiversive rotations. The number of animals used in each experimental group is as follows: PBS group: n = 3; Vpr group: n = 3; ΔVpr-77R-ND group: n = 4; ΔVpr-77Q-HAD group: n = 4 (M-N, Dunnett test, relative to control; *p < 0.05). Original magnification 400×.