BackgroundOptogenetic tools enable cell selective and temporally precise control of neuronal activity; yet, difficulties in delivering sufficient light to the spinal cord of freely behaving animals have hampered the use of spinal optogenetic approaches to produce analgesia. We describe an epidural optic fiber designed for chronic spinal optogenetics that enables the precise delivery of light at multiple wavelengths to the spinal cord dorsal horn and sensory afferents.ResultsThe epidural delivery of light enabled the optogenetic modulation of nociceptive processes at the spinal level. The acute and repeated activation of channelrhodopsin-2 expressing nociceptive afferents produced robust nocifensive behavior and mechanical sensitization in freely behaving mice, respectively. The optogenetic inhibition of GABAergic interneurons in the spinal cord dorsal horn through the activation of archaerhodopsin also produced a transient, but selective induction of mechanical hypersensitivity. Finally, we demonstrate the capacity of optogenetics to produce analgesia in freely behaving mice through the inhibition of nociceptive afferents via archaerhodopsin.ConclusionEpidural optogenetics provides a robust and powerful solution for activation of both excitatory and inhibitory opsins in sensory processing pathways. Our results demonstrate the potential of spinal optogenetics to modulate sensory behavior and produce analgesia in freely behaving animals.

Objective: The present study aims at measuring the association between household food insecurity and psychological distress in adolescents in Inuit communities, concurrently and overtime from childhood to adolescence. Design: The study used measures of internalising behaviours (anxiety, withdrawn attitude, somatic complaints and depression) as indicators of psychological distress during adolescence, a concurrent measure of household food insecurity in adolescence and an assessment of longitudinal patterns of household food insecurity from childhood to adolescence. We collected descriptive information at birth, childhood and adolescence on potential confounders. Setting: Inuit communities of Nunavik in northern Quebec, Canada Participants: The study consisted of 212 participants from the Nunavik Child Development Study, who have been assessed at birth, childhood (mean age = 11 years, range = 9–13 years) and adolescence (mean age = 18 years, range = 16–21 years). Results: Concurrent severe household food insecurity in adolescence was associated with higher measures of psychological distress: depression (βstd = 0·26, P < 0·01) and withdrawn attitude (βstd = 0·20, P = 0·04). Persistent household food insecurity (both at childhood and adolescence) was associated with higher levels of adolescent depression (βstd = 0·18, P = 0·02) and anxiety (βstd = 0·17, P = 0·03). Conclusions: Adolescents from Nunavik living with higher food insecurity and those having experienced food insecurity in both childhood and adolescence were more likely to report symptoms of psychological distress. Considering the high level of distress experienced by young Inuit, existing initiatives to reduce food insecurity in Nunavik communities should be targeted to include children and adolescents.

No abstract