Acute gelatinase inhibitor does not attenuate deficits in social behavior at adulthood after pediatric TBI.

<p>(A) Social investigation was quantified by the resident-intruder paradigm, revealing that TBI mice as compared to sham controls spent less time investigating a naïve intruder mouse (2-way ANOVA overall effect of TBI, **p<0.01). (B) In the three-chamber social approach task (stage 2), all mice showed an overall preference for sociability with stimulus mouse 1 compared to the empty chamber (2-way RM ANOVA overall effect of chamber, p = 0.0003). (C) Stage 3 of the three-chamber task tested social novelty. Here, sham-operated mice revealed a preference for a novel stimulus mouse compared to the now-familiar mouse (2-way RM ANOVA interaction, p = 0.0055; subsequent Sidak’s post-hoc tests, ***p<0.001, ****p<0.0001 as indicated graphically). In contrast, TBI mice showed a lack of of social memory (n.s. by Sidak's post-hoc) (n = 15/group). Bars represent mean + sem.</p

Cognitive deficits detected in the Morris water maze (MWM) at adulthood after pediatric TBI, are unaffected by gelatinase inhibition.

<p>(A) During the visible sessions, quantification of latency to reach the platform revealed an impairment in task learning by TBI mice compared to sham controls (multivariate ANOVA overall effect of TBI, **p<0.01). (B) During hidden platform sessions, injured mice also showed a greater latency to reach the platform as compared to sham controls (overall effect of TBI, ***p<0.001), indicating an impairment in spatial memory. Cumulative distance to the target was also quantified as an alternative outcome measure (C-D), which similarly detected impairments in task performance and spatial memory in TBI mice compared to sham controls (overall effect of TBI, **p<0.01). (E) Probe trial performance was quantified as cumulative distance to the target. Injured mice traveled a greater distance to reach the target quadrant compared to sham controls (RM ANOVA, overall effect of TBI, **p<0.01) (n = 15/group). Bars represent mean + sem and values represent mean ± sem.</p

Gelatinase inhibition with <i>p</i>-OH SB-3CT does not attenuate extensive injury-induced loss of cortical and hippocampal structures.

<p>Volumetric estimates spanning Bregma 1.5 to -3.8mm in the cortex (Ctx; A), hippocampus (Hpc; B) and dentate gyrus (DG; C) revealed injury-induced reductions (unpaired t-tests *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001 as indicated graphically; n = 11–15/group). (D) Unbiased cell counts performed in the ipsilateral DG found similar numbers of surviving neurons in the upper and lower blades of injured mice independent of drug treatment (n = 8–9/group). Bars represent mean + sem.</p

Concentrations of <i>p</i>-OH SB-3CT after multiple-dose s.c. administration.

<p>^<i>a</i> Concentrations in pmol/mg tissue</p><p>^<i>b</i> Concentrations in μM</p><p>^<i>c</i> NQ = not quantifiable</p><p>AUC = area under the curve</p><p>^<i>d</i><i>AUC</i> in pmol·min/mg for brain and in μM·min for plasma</p><p>Concentrations of <i>p</i>-OH SB-3CT after multiple-dose s.c. administration.</p

Enhanced gelatinases detected at 48 h after TBI.

<p>(A) Gelatin zymography from representative brain lysates indicates increased expression of MMP-9 and MMP-2 at 48 h post-injury as compared to sham controls. The pro-forms of MMP-9 and MMP-2 were detected at ~105 and 72 kDa, respectively. Purified human MMP-2 and MMP-9 were used as standards. (B) Quantification of band intensity revealed a robust increase in the pro-enzyme forms of MMP-2 and (C) MMP-9, as well as increases in the active enzyme forms after TBI compared to sham (n = 6 per group; unpaired t-tests, *p<0.05, **p<0.01 and ***p<0.001, TBI compared to sham). Bars represent mean + sem.</p

Early gelatinase inhibition does not impact injury-induced hyperactivity, measures of anxiety, or motor function at adulthood after pediatric TBI.

<p>(A) Injury resulted in hyperactivity by adulthood, indicated by increased total distance traveled in an open field (2-way ANOVA, effect of injury, **p<0.01). (B) The percent time spent in center of the open field, a measure of anxiety, was not altered by either injury or treatment (2-way ANOVA n.s.). (C) Anxiety was also measured by percent time spent in the open arms of the elevated plus maze, and neither injury nor <i>p</i>-OH SB-3CT treatment affected this measure (2-way ANOVA n.s.). (D) Motor function, evaluated by latency to fall from an accelerating rotarod, was similar in all groups across consecutive testing days (2-way RM ANOVA). Bars represent mean + sem and values represent mean ± sem (n = 15/group).</p