EE in Marlau™ cages immediately after Li-Pilo-SE at weaning improves LTP in CA1 pyramidal neurons observed 1–2 weeks later after SE.

<p><b>A.</b> Induction of LTP in CA1 neurons was significantly (p = 0.0003) impaired in slices of rats housed in conventional cages following Li-Pilo-SE (n = 14) compared with healthy rats housed in the same cages (n = 13). <b>B.</b> Induction of LTP in CA1 neurons was significantly decreased (p = 0.0006) in slices of rats housed in Marlau™ cages following Li-Pilo-SE (n = 11) compared with healthy rats housed in the same cages (n = 12). <b>C.</b> LTP in CA1 pyramidal neurons of rats subjected to Li-Pilo-SE at weaning was significantly higher (p = 0.0003) when rats were housed in Marlau™ cages (n = 11) compared to those housed in conventional cages (n = 14). <b>D.</b> Induction of LTP in rats subjected to Li-Pilo-SE and then housed in Marlau™ cages (n = 11) was statistically similar (p = 0.98) to that of healthy rats housed in conventional cages (n = 13). The top traces show EPSPs before and after LTP induction. Arrow marks the starting point of tetanus stimulation. Results are presented as the mean ± SEM (n = number of cells; 1–2 cell(s) per rat). Abbreviations: Cv and En as in Fig. 1.</p

Rats raised in Marlau™ cages after excitotoxic brain injury displayed decreased cognitive impairments.

<p>Rats underwent pilocarpine-induced <i>status epilepticus</i> (Pilo-SE) at 3 week-old, and were raised, on the following day, either in conventional or Marlau™ cages. Rats developing spontaneous recurrent seizures (SRS, or “epileptic”) were then subjected at 15- and 16-week old to the WET and to the MWM, respectively. In these results, 10 rats not subjected to Pilo-SE were included in each Cv and En groups. The number of rats subjected to Pilo-SE that developed SRS was not identical in each Cv (n = 16/18) and En (n = 9/18) groups. <b>A.</b> WET. While rats undergoing SRS displayed marked anxiety-like behavior, the positive effect of enrichment in control rats was observed in epileptic rats, as demonstrated by the increased time spent floating in the central zone. Cv-E vs. Cv and En-E vs. En: ** p<0.01, *** p<0.01; En-E vs. Cv-E: p<0.01, ANOVA 2. <b>B.</b> MWM. Enriched housing prevented the deterioration of learning and memory observed in conventional housing, as indicated by the latency to find the platform and the proportion of rats finding the platform. Cv-E vs. Cv: * p<0.05, ** p<0.01, *** p<0.01; En-E vs. Cv-E: p<0.01, two-way repeated measures ANOVA. Abbreviations: Cv and En as in Fig. 1; En-E, epileptic rats housed in enriched Marlau™ cages; Cv-E, epileptic rats housed in conventional cages.</p

Rat weight, but not total body fat, is increased after housing in the Marlau™ cage. A.

<p>After 4 weeks in the Marlau™ cage, “enriched” rats had an increase in body weight that was significantly greater than that of rats raised in conventional conditions (n = 12 in each group). <b>B.</b> Total body fat percentage measured at termination time was not altered by housing conditions (n = 8 in each group). All results are expressed as the mean ± SEM. Abbreviations: Cv, rats in conventional cages; En, rats in Marlau™ cages.</p

Marlau™ cages meet the criterion of enrichment-induced hippocampal neurogenesis.

<p>Fourteen days after BrdU injections, the averaged number of cells having incorporated BrdU (counted in 3 sections, 300 µm apart) nearly doubled in the hippocampus of rats raised in Marlau™ cages. While BrdU could be detected in both neurons and astrocytes, respectively identified by NeuN and GFAP, BrdU was primarily found in neurons. En vs. Cv: *** p<0.001, two-way ANOVA, factor 1: rat group, factor 2: anatomical plane. Each bar represents the mean ± SEM (<i>n = 4</i> in each group). Abbreviations: Cv and En as in Fig. 1.</p

Longitudinal analysis of exploratory behavior during housing in Marlau™ cages is in favor of decreased anxiety in “enriched” rats.

<p>Rats were consecutively tested in the WET (A), in the BWB (B), and in the EPM (C), respectively after one, three and twelve weeks of housing in Marlau™ or conventional cages. <b>A.</b> WET. <i>a,</i> rats are placed in a pool divided into 4 quadrants for 5 min; visiting the virtual “central zone” (CZ, green) was indicative of reduced anxiety; <i>b,</i> typical trajectories of S and En rats; <i>c,</i> time spent and distance traveled in the full quadrant and the CZ; <i>d,</i> time spent in the CZ swimming with different velocity profiles: rapid, slow, and null (floating behavior). Each bar represents the mean ± SEM (<i>n = 12</i> in each group). <b>B.</b> BWB. <i>a,</i> rats were tested during 2 consecutive days (with access to the SBZ on day 2 only); visiting the WZ on day 1 and the SBZ on day 2 was indicative of reduced anxiety; <i>b-d,</i> we measured the number of rats visiting the WZ on days 1 and 2 (<i>b</i>), the percentage of those returning to the WZ on day 2 (<i>c</i>), and the number of rats visiting the SBZ on day 2 (<i>d</i>). Each bar represents the mean of the group (n = 12 in each group). <b>C.</b> EPM. <i>a</i>, exploratory behavior of rats was tested for 5 min once placed in an open arm (OA), as shown; exploration of the OA was indicative of reduced anxiety; <i>b,</i> we measured the number of rats visiting the OA, the number of entries in the OA, and the time spent in the OA; <i>c,</i> while the time spent to explore the closed arms (CA) was mostly restricted to one arm in “conventional” rats, the “enriched” rats explored nearly equally both CA. En vs. Cv: ** p<0.01, *** p<0.001, Student’s <i>t</i> test. Abbreviations: Cv and En as in Fig. 1.</p

Effect of FG-7142 (25 mg/kg, i.p.) and diazepam (3 mg/kg; i.p.) treatments, administered 30 min prior to WET in Sprague-Dawley rats at 9 weeks of age, raised in conventional cages.

<p>Differences between controls and FG-7142 or diazepam-treated rats:</p>*<p>p<0.05;</p>**<p>p<0.01;</p>***<p>p<0.001 (ANOVA 1).</p

Marlau™ cages meet the criterion of enrichment-induced cortical thickness.

<p>Six weeks after housing in Marlau™ cages, averaged cortical thickness measured as shown by colored arrows on Nissl-stained sections was increased compared to conventional conditions, especially in M1 and S1 subregions. En vs. Cv: * p<0.05, ** p<0.01, two-way ANOVA, factor 1: rat group, factor 2: subregion. Each bar represents the mean ± SEM (<i>n = 4</i> in each group). Abbreviations: Cv and En as in Fig. 1; Cg1/2, cingular cortex 1 and 2; M1, primary motor cortex; M2, secondary motor cortex; RSGb, retrosplenial granular b cortex; S1BF, primary somatosensory cortex, barrel field; S1ULp, primary somatosensory cortex, upper lip region.</p

Effect of FG-7142 (25 mg/kg, i.p.) treatment, administered 30 min prior to WET in Sprague-Dawley rats at 9 weeks of age and raised in Marlau™ cages for 6 weeks.

<p>Differences between controls and FG-7142:</p>*<p>p<0.05;</p>**<p>p<0.01;</p>***<p>p<0.001 (ANOVA 1).</p

Number of cDNA copies (mean ± SEM) after reverse transcription of 1 µg of total RNAs contained in the ventral and dorsal hippocampus dissected from the brains of 9 week-old rats housed in conventional cages (n = 8).

<p>Differences between dorsal and ventral hippocampus:</p>***<p>p<0.001, Student’s <i>t</i> test;</p><p>NS: not significantly different.</p

Rats raised in Marlau™ cages display better capacity to cope with restraint stress. A.

<p>Plasma corticosterone level was measured 30 min prior to (basal), at the end of a 30 min-restraint stress and after 2-hour recovery period (n = 5 in each group). En vs. Cv: * p<0.05, following two-way repeated measures ANOVA. <b>B.</b> Transcript levels for corticosteroid receptors (MR and GR) were measured in the dorsal and ventral hippocampus of naïve rats raised in conventional or Marlau™ cages (n = 7 in each group). Note that increased hippocampal transcript level of GR and MR was associated with a faster recovery of basal CORT level after restraint stress. En vs. Cv: * p<0.05, ** p<0.01, following two-way ANOVA, factor 1: rat group, factor 2: hippocampal subregion. Abbreviations: Cv and En as in Fig. 1.</p