Arousal mechanism after sevoflurane anesthesia in rats: orexinergic modulation in dorsal raphe nucleus by optogenetic and chemogenetic techniques / 中华麻醉学杂志

ABSTRACT

Objective:To investigate the arousal mechanism after sevoflurane anesthesia using orexinergic modulation in dorsal raphe nucleus(DRN) by optogenetic and chemogenetic techniques in rats.Methods:Forty-five healthy male Hcrt-Cre rats, aged 10-12 weeks, weighing 220-250 g, were divided into 6 groups by the random number table method: optical-excitatory group (CHR2 group, n=5), optical-inhibitory group (eNpHR group, n=5), optical-control group (O-CON group, n=5); chemogenetic-excitatory group (hm3Dq group, n=10), chemogenetic-inhibitory group (hm4Di group, n=10) and chemogenetic-control group (C-CON group, n=10). The optogenetic or chemogenetic techniques were used in each group. Three weeks after injecting the rat virus, anesthesia was induced and maintained with 2.7% sevoflurane anesthesia in 1.5 L/min O 2, and the EEG data were continuously recorded throughout the process. The burst suppression ratio (%BSR) was recorded at 2 min before and of laser stimulation. Combining optogenetic and chemogenetic strategies, it was investigated that whether activation of orexinergic projection to DRN could modulate anesthetic behaviors during sevoflurane anesthesia. Results:Compared with C-CON group, the recovery of righting reflex (RORR) time was significantly shortened after sevoflurane anesthesia in hm3Dq group ( P<0.05), and the RORR time was significantly prolonged after sevoflurane anesthesia in hm4Di group and eNpHR group ( P<0.05). Compared with O-CON group or the baseline at 2 min before light stimulation, the %BSR was significantly decreased during 473nm laser stimulation in CHR2 group ( P<0.05), and no statistically significant change was found in the %BSR during 473nm laser stimulation in eNpHR group ( P>0.05). Compared with O-CON group, the RORR time was significantly shortened after sevoflurane anesthesia in CHR2 group ( P<0.05). Conclusions:Lateral hypothalamic area orexin-DRN neural circuit plays a key role in promoting arousal from general anesthesia in rats.