Rapid, onsite cytological examination was performed in all cases

amplitude = 1.53, p = 0.147) suggesting that 2-AG is not responsible for mediating the EC tone regulating up-states. Altered up-state parameters in BCTC cortical cultures from CB1 KO mice As noted earlier, AM281 reduced up-state duration in wild-type cultures but did not affect duration of up-states in KO cultures. As a further test of the hypothesis that CB1 signaling is necessary for the manifestation of up-states, baseline measures of up-state parameters were compared between cultures prepared from wt and CB1 KO mice. Up-state amplitude did not differ between genotypes = 1.06, p = 0.3), but, in contrast to that found with CB1 antagonists, up-state duration in KO cultures was significantly enhanced as compared to control cultures = 5.78, p,0.001). This was accompanied by an increase in the total number of spikes generated during the upstate = 2.29, p = 0.029). These results demonstrate that signaling through CB1 is not necessary for the manifestation of the up-states, but in the chronic absence of CB1, cortical network activity is dysregulated resulting in increased excitability. Thus, signaling through CB1 is necessary for shaping normal patterns of cortical activity. Genetic Deletion of the CNR1 Gene Reduces NREM Sleep Because the longer duration up-states observed in CB1 KO cultures reflect greater cortical activity, we hypothesized that sleep and delta frequency oscillations would be reduced in CB1 KO mice. To test this, ECoG and EMG recordings were obtained from CB1 KO mice PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19645691 and wt littermates and scored for sleep-wake states. A comparison of time spent in the three main behavioral states showed that CB1 KO mice spend more time in wake at the expense of NREM. Specifically, there was a significant interaction between time of day and genotype nested within photoperiod for the total time spent in wake = 2.67, p = 0.007) with a main effect of genotype = 11.30, p = 0.002). Pair-wise comparisons revealed a significant increase in the amount of time CB1 KOs spent awake during the first 6 hours of the dark phase = 6.55, p = 0.012; 9 to 12 am, F = 4.71, p = 0.033). An analysis of wake architecture across the circadian cycle found no genotypic differences in either the number of wake bouts or their duration. These results indicate that CB1 KO mice exhibit a more active phenotype than wt mice. The increase in wake observed in CB1 KO mice is exclusively due to reduced time spent in NREM sleep. There was a significant 3-way interaction for the time spent in NREM = 2.11, p = 0.032) and a main effect of genotype = 12.389, p = 0.002). Post-hoc analyses revealed a significant reduction in NREM for CB1 KO mice for the first half of the dark photoperiod = 6.43, p = 0.013; 9 to 12 am, F = 4.84, p = 0.031) which is the active period for mice. An analysis of NREM architecture found that CB1 KO mice have reduced duration of NREM bouts = 10.55, p = 0.009) particularly during the dark photoperiod = 3.071, p = 0.012). There was no genotypic effect on the number of NREM bouts as evidenced by the lack of a main effect of genotype = 2.318, p = P = 0.159) or significant interaction between genotype and photoperiod = 0.5931, p = 0.459). These data demonstrate that the reduction in NREM sleep observed in CB1 KO mice was mainly the result of decreased bout duration, suggesting that chronic loss of CB1 destabilizes the NREM. To gauge the effects of CB1 deletion on slow-wave oscillations, Fast Fourier Transform was performed on the ECoG waveform, and the resulting power