Dexmedetomidine hydrochloride

Brain fMRI scans were conducted with a Bruker 11.7 T MRI system (BioSpec117/16 USR-TT, Bruker, Karlsruhe, Germany) with a 16.0 cm aperture and a 12 cm gradient coil before surgery (baseline) and at D7 and D28 following CCD surgery. The radiofrequency (RF) coil contained a 72 mm inner diameter volumetric coil as the excitation coil and a four-channel surface coil as the receiving coil. After anesthesia with 4% isoflurane (RWD Life Science Co., Ltd., Shenzhen, China), the rats were attached to the scanner in supine position, with the head fixed to the rat specific coil and placed at the center of the magnetic field. The automatic heating pad maintained the anal temperature of rats between 36°C and 38°C. Continuous anesthesia was maintained with ventilated dexmedetomidine hydrochloride (Sigma Aldrich) under continuous respiratory monitoring. An interleaved single echo planar imaging sequence adhered to the following parameters: flip angle: 90°; slice thickness: 0.5 mm; repetition time: 2000 ms; echo time: 12.8 ms; mean value: 1; field of view: 30 × 30 mm² with 128 × 128.

P7 rat pups of equally distributed sexes were injected with 25 µg/kg of dexmedetomidine (DEX) (Dexmedetomidine hydrochloride, Sigma-Aldrich cat. SML0956) subcutaneously either once (1×) or twice (2×), (24h after the first injection), using a 0.1 mL volume. Control animals were injected with an equivalent volume of saline (sodium chloride 0.9% Braun, Mississauga, ON, Canada). Body temperature was maintained with the use of a heated blanket and gloves filled with warm water replaced every 20 min [31 (link)]. The respiratory rate of the animal was monitored by counting breaths per minute and checked every 10 min following the first injection over the subsequent 30 min, to confirm the pup’s health. Furthermore, oxygen saturation (SpO₂) was monitored every 30 min following each injection for a period of an hour to further ensure the pup’s health and reaction to the compound (Nonin Medical, Minneapolis, MN, USA).