Synthetic cannabinoids are psychoactive substances designed to mimic the euphorigenic effects of the natural cannabis. Novel unregulated compounds appear once older compounds become illegal. It has been previously reported that synthetic cannabinoids are different than Δ -tetrahydrocannabinol (Δ -THC) as they have chemical structures unrelated to Δ -THC, different metabolism and, often, greater toxicity. This study aimed to investigate the effects of three novel synthetic cannabinoids and pure Δ -THC on body temperature, nociceptive threshold, anxiety, memory function, locomotor and exploratory parameters, and depression. We performed a battery of behavioural and motor tests starting 50 minutes post i.p. injection of each drug to adult ICR mice. The synthetic cannabinoids that were used are AB-FUBINACA, AB-CHMINACA and PB-22. All synthetic cannabinoids and Δ -THC caused hypothermia, but only Δ -THC induced a clear antinociceptive effect. All synthetic cannabinoids and Δ -THC caused decreased anxiety levels, spatial memory deficits and decreased exploratory behaviour as measured in the elevated plus maze, Y-maze and staircase paradigm, respectively. However, all synthetic cannabinoids but not Δ -THC demonstrated decreased locomotor activity in the staircase test. Moreover, only AB-FUBINACA and Δ -THC affected the gait balance and grip strength of the mice as was assessed by the latency time to fall from a rod. In the forced swimming test, PB-22 caused elevated depression-like behaviour while AB-FUBINACA induced a reversed effect. These results suggest varied effects among different synthetic cannabinoids and Δ -THC. Further studies are needed to characterize the overall effects and differences between these synthetic cannabinoids and Δ -THC.
Introduction
Homotopic functional connectivity (HoFC), the synchrony in activity patterns between homologous brain regions, is a fundamental characteristic of resting-state functional connectivity (RsFC).
Methods
We examined the difference in HoFC, computed as the correlation between atlas-based regions and their counterpart on the opposite hemisphere, in 16 moderate–severe traumatic brain injury patients (msTBI) and 36 healthy controls. Regions of decreased HoFC in msTBI patients were further used as seeds for examining differences between groups in correlations with other brain regions. Finally, we computed logistic regression models of regional HoFC and fractional anisotropy (FA) of the corpus callosum (CC).
Results
TBI patients exhibited decreased HoFC in the middle and posterior cingulate cortex, thalamus, superior temporal pole, and cerebellum III. Furthermore, decreased RsFC was found between left cerebellum III and right parahippocampal cortex and vermis, between superior temporal pole and left caudate and medial left and right frontal orbital gyri. Thalamic HoFC and FA of the CC discriminate patients as msTBI with a high accuracy of 96%.
Conclusion
TBI is associated with regionally decreased HoFC. Moreover, a multimodality model of interhemispheric connectivity allowed for a high degree of accuracy in disease discrimination and enabled a deeper understanding of TBI effects on brain interhemispheric reorganization post-TBI.
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