Article Figures & Data
Figures
- Fig. 1.
A, B, Effect of repeated d-amphetamine or saline injections on activity counts accumulated over 2 hr after injection in experiment 1 (A) and experiment 2 (B). The data are represented as mean (± SEM) activity counts. There was a significant interaction between group and injection number in both experiments: experiment 1, F(1,16) = 5.60,p < 0.05; experiment 2,F(1,18) = 12.44, p < 0.01. Between-group comparisons, ***p < 0.001, using simple main effects analysis. Within-group comparisons, †p < 0.01, ‡p < 0.001, using Newman–Keuls post hoc test.
- Fig. 2.
Effect of d-amphetamine or saline pretreatment on latencies to mount and intromit. A, Kaplan–Meier curve for mount latency (left panel) and intromission latency (right panel) in experiment 1. Independent survival analyses showed a significant difference between sensitized (AMPH) and nonsensitized (CONT) rats with respect to mount latency (Log rank statistic = 9.43; p = 0.0021) and intromission latency (Log rank statistic = 10.48; p = 0.0012). B, Kaplan–Meier curve for mount latency (left panel) and intromission latency (right panel) in experiment 2. Independent survival analyses showed a significant difference between sensitized (AMPH) and nonsensitized (CONT) rats with respect to mount latency (Log rank statistic = 6.12; p = 0.0134) and intromission latency (Log rank statistic = 4.38;p = 0.0364).
- Fig. 3.
Changes in nucleus accumbens dopamine efflux (line graph) during baseline (Bas), while a receptive female was present behind the screen (Scr), during copulation, and after copulation for CONT and AMPH rats. Bar graphs show the number of mounts plus intromissions (top bar graph) and ejaculations (bottom bar graph) displayed for each group during three 10 min samples. *p < 0.05; **p < 0.01 using simple main effects analysis. Within-group Newman–Keuls post hoc tests revealed significant (p < 0.05) increases in nucleus accumbens DA concentrations from baseline in AMPH (time = 20–50 min) and CONT (time = 30–50 min) rats.
- Fig. 4.
Changes in DOPAC (top panel) and HVA (bottom panel) concentrations in the nucleus accumbens during baseline (Bas), while a receptive female was present behind the screen (Scr), during copulation, and after copulation. Within-group Newman–Keulspost hoc tests revealed significant (p < 0.05) increases in nucleus accumbens metabolite concentrations from baseline in AMPH (DOPAC, time = 30–80 min; HVA, time = 30–90 min) and CONT (DOPAC, time = 30–90 min; HVA, time = 50–100 min) rats.
- Fig. 5.
Changes in nucleus accumbens dopamine efflux in response to a d-amphetamine challenge (1.5 mg/kg, i.p.). *p < 0.05; **p < 0.01 using simple main effects analysis. Dopamine concentrations and activity counts remained elevated throughout the 2 hr postinjection period relative to baseline (Bas) in both groups.
- Fig. 6.
Location of microdialysis probes within the nucleus accumbens of rats used in experiment 2. Vertical black lines correspond to the location of the active fiber area of the microdialysis probes. For reasons of clarity, probe placements of CONT rats are displayed on the left, and those of AMPH rats are shown on the right. Coronal brain sections redrawn from Paxinos and Watson (1997).
Tables
Experiment 1 Experiment 2 CONT AMPH CONT AMPH ML (sec) 219.1 ± 111.7 31.3 ± 12.1* 37.3 ± 18.6 18.4 ± 4.5 IL (sec) 271.0 ± 106.2 54.4 ± 21.9* 53.8 ± 36.2 24.3 ± 3.5 EL (sec) 621.5 ± 181.3 583.0 ± 101.3 611.2 ± 76.9 493.6 ± 64.8 PEI (sec) 428.6 ± 124.9 389.2 ± 40.1 357.3 ± 25.0 330.9 ± 21.9 MF 9.9 ± 2.9 15.7 ± 2.3 3.5 ± 1.1 6.3 ± 1.4 IE1 8.3 ± 1.4 10.3 ± 1.3 11.5 ± 1.4 10.6 ± 2.1 IF 10.4 ± 2.8 17.9 ± 1.7* 16.0 ± 4.3 20.9 ± 2.8 EF 1.1 ± 0.4 2.3 ± 0.3* 1.9 ± 0.5 3.1 ± 0.3* III 76.6 ± 16.1 57.1 ± 8.5 59.7 ± 15.3 52.6 ± 8.3 IR 0.58 ± 0.09 0.58 ± 0.04 0.82 ± 0.06 0.72 ± 0.05 Data are expressed as the mean ± SEM.
ML, Mount latency; IL, intromission latency; EL, ejaculation latency; PEI, postejaculatory interval; MF, mount frequency; IE1, intromissions before the first ejaculation; IF, intromission frequency; EF, ejaculation frequency; III, interintromission interval; IR, intromission ratio.
Different than CONT group for a given measure, *p < 0.05.
CONT AMPH DA (nm) 3.9 ± 0.7 3.3 ± 0.5 DOPAC (nm) 820.8 ± 139.4 618.8 ± 94.4 HVA (nm) 283.1 ± 39.1 243.9 ± 29.1 Data are expressed as the mean ± SEM (uncorrected for probe recovery).
DA, Dopamine; DOPAC, dihydroxyphenylacetic acid; HVA, homovanillic acid.
