The investigative rearing deficit in male <i>Nf1</i> OPG mice is not rescued by L-dopa administration.

<p>(A–C) No significant overall effects of Group were found in the third cohort of mice for ambulatory activity (A), rearing frequency (B), or time spent rearing (C) during a 30-min habituation trial in the open-field apparatus, which was conducted the day before the test session and did not include any drug/vehicle injections. (D) In contrast, planned comparisons showed that the CON+SAL mice spent significantly more time rearing to investigate the hanging object (ball) compared to the time spent rearing in the same area at the opposite end of the field (BALL vs OPP; *p = 0.017), while the <i>Nf1</i> OPG+SAL group did not show significantly different rearing times with regard to the ball versus the opposite area. The <i>Nf1</i> OPG+LDOPA mice reared for substantially longer times in investigating the ball versus the opposite area but these differences were not statistically significant (p = 0.064). (E) Similar results were found for the rearing frequency data where planned comparisons revealed that the CON+SAL mice spent significantly more time rearing to investigate the hanging ball versus the time spent rearing in the opposite area of the field (BALL vs OPP; *p = 0.010), while the <i>Nf1</i> OPG+SAL group did not. Again, the <i>Nf1</i> OPG+LDOPA mice showed a trend toward greater investigative rearing toward the ball versus the opposite area but these differences were not statistically significant (p = 0.063). (F) Although the <i>Nf1</i> OPG+SAL mice tended to spend less time rearing in general throughout the field compared to the CON+SAL and <i>Nf1</i> OPG+LDOPA groups, no statistically significant effects were observed for this variable. The male mice in cohort 3 were 3.5–4.5 months old and the sample size for each of the three groups was the same (n = 12).</p

Mouse cohorts used for behavioral tests.

<p>Ages of mice at testing, order of behavioral tests and sex distribution for each mouse cohort used in the present study.</p

Habituation increases exploratory hole poking in male <i>Nf1</i> OPG mice and L-dopa administration rescues normal olfactory preference behaviors.

<p>(A–C) In cohort 3, no differences were observed between saline-treated WT control mice (CON+SAL), saline-treated <i>Nf1</i> OPG mice (<i>Nf1</i> OPG+SAL) or <i>Nf1</i> OPG mice treated with L-dopa (<i>Nf1</i> OPG+LDOPA) in terms of total hole pokes (A), total side pokes (B), or general ambulatory activity (C). (D) However, planned comparisons showed that the CON+SAL and <i>Nf1</i> OPG+LDOPA groups displayed a significant preference (increased poke frequency) for the odorant-containing versus the empty corner holes (EMP vs ODR; **p = 0.003 and *p = 0.020, respectively), while the <i>Nf1</i> OPG+SAL mice did not show a significant preference. (E) Similarly, the CON+SAL and <i>Nf1</i> OPG+LDOPA mice exhibited a significant preference for the familiar (fresh homecage bedding) versus the novel (coconut) odorant (NOV vs FAM; *p = 0.0001 and **p<0.00005, respectively), in contrast to the <i>Nf1</i> OPG+SAL group which again did not show a significant preference. In addition, the <i>Nf1</i> OPG+SAL mice poked significantly more often into the hole containing the novel odorant compared to the levels observed in the <i>Nf1</i> OPG+LDOPA group (^†p = 0.016). (F) The average hole poke durations were significantly greater for the odorant-containing versus the empty holes in both the CON+SAL and <i>Nf1</i> OPG+LDOPA groups (EMP vs ODR; **p = 0.001 and *p = 0.041, respectively), while the <i>Nf1</i> OPG+SAL mice did not show significant differences in poke durations for the different types of holes. The mice in cohort 3 were all males that were 3.5–4.5 months of age and each of the three groups had the same sample size (n = 12).</p

<i>Nf1</i> OPG mice show decreased spontaneous alternations in a Y-maze but no deficits in spatial working memory or long-term depression (LTD) in hippocampal slices.

<p>(A–B) In cohort 1, <i>Nf1</i> OPG mice (n = 20; M = 8; F = 12) made significantly fewer alternations (A; *p = 0.008) and arm entries (B; *p = 0.011) compared to WT control mice (n = 17; M = 10; F = 7) suggesting a diminished response to novelty in the <i>Nf1</i> mutant mice. (C) To control for differences in activity, alternation scores were transformed with reference to the number of arm entries in calculating the percentage of spontaneous alternations, and no significant differences in performance were observed between groups suggesting intact spatial working memory in the <i>Nf1</i> OPG mice. The mice in cohort 1 were 5 months of age. (D) The graph shows the time course of change in EPSP slope in response to 900 pulse LFS delivered at 1 Hz (connected arrows). LFS produced robust LTD in hippocampal slices from both WT control and <i>Nf1</i> OPG mice. Traces to the right of the graph show representative EPSPs from control and <i>Nf1</i> OPG slices during baseline (dashed traces) and 60 min following LFS (solid traces). Scale = 1 mv, 5 ms.</p

<i>Nf1</i> OPG mice exhibit an abnormal response to novel environmental stimuli in an open field.

<p>(A) In the cohort 2 mice, locomotor and exploratory activity were quantified over a 30-min period in an open field. An rmANOVA and pair-wise comparisons revealed that <i>Nf1</i> OPG mice showed significantly (beyond Bonferroni correction: p<0.017) reduced total ambulations (whole body movements) compared to WT littermate controls but only during the first 10-min block of the open-field test (*p = 0.015), although large differences were also observed during Block 2 (^†p = 0.038) (Genotype effect: ^††p = 0.027; Genotype by Time interaction: ^††p = 0.033). (B) Similarly, <i>Nf1</i> OPG mice exhibited significantly decreased numbers of vertical rearings during only the first 10-min time block as well (*p = 0.010). (Genotype by Time interaction: ^†p = 0.043). (C) The <i>Nf1</i> OPG mice also spent significantly less total time rearing in the open field compared to control mice (*p = 0.005) during the first time block with large differences also being observed for the second time block (^†p = 0.046), (Genotype effect: F(1,16) = 5.00, **p = 0.040). (D) <i>Nf1</i> OPG mice displayed significantly reduced rearing to investigate an object (ball) suspended on one side of the open field apparatus relative to control mice (*p = 0.014) although the groups did not differ in the time spent rearing in the same area on the opposite side of the field. In addition, the WT control mice showed significantly increased rearing times to investigate the ball relative to the amount of rearing time displayed on the opposite side of the field (BALL vs OPP; **p = 0.0001), while no significant differences were found in terms of the rearing times between the two areas in <i>Nf1</i> OPG mice. (E) <i>Nf1</i> OPG mice spent significantly less time rearing in the open field in general (*p = 0.014) compared to the control group. (F) When rearing to investigate the hanging object and rearing displayed in the same area on the opposite side of the field were calculated as percentages of the total rearing time, the WT control mice, but not the <i>Nf1</i> OPG mice, showed significant differences in rearing to investigate the ball versus rearing on the opposite side of the field (BALL vs OPP; **p = 0.001). During the open-field testing, the cohort 2 groups were 5.5 months old and consisted of the same sample sizes and sex distribution (n = 10: M = 4; F = 6).</p

<i>Nf1</i> OPG mice display context-dependent alterations in activity in the elevated plus maze (EPM).

<p>No differences were observed in the distances traveled by the <i>Nf1</i> OPG mice compared to the WT littermate control group from cohort 2 (4.5 months old) in either the open arms (A) or in the center area of the EPM (B). (C) However, the <i>Nf1</i> OPG mice traveled a significantly shorter total distance throughout the entire EPM compared to the control group (Genotype effect: ^††p = 0.009) with significant differences between groups occurring on Test Days 2 (*p = 0.015) and 3 (**p = 0.009). (D) The differences in total distance traveled were found to be mostly due to differences between the two groups in distance traveled in the relatively non-threatening closed arms. Specifically, the <i>Nf1</i> OPG mice, on average, traveled a significantly shorter distance in the closed arms compared to the WT controls (Genotype effect: ^††p = 0.0015), with significant differences being found on Test Days 2 (**p = 0.003) 3 (*p = 0.006), although large differences were also found on Test Day 1 as well (^†p = 0.024). For both groups in cohort 2 the sample sizes were the same (n = 10), as was the sex distribution (M = 4; F = 6).</p