Guide cannula

Following anesthetization, the mice were placed in the stereotaxic apparatus (RWD life science Co. Ltd., China). In accordance with previous reports (10 (link)), guide cannulas (RWD life science Co. Ltd., China) were planted into the right lateral ventricle (coordinates: 0.6 mm posterior to the bregma, 1.5mm lateral, 2mm depth from the dura) and secured to the skull with dental cement. All the mice were allowed to recover in clean cages for 7 days. And handled daily to check the guide cannula and familiarize them with the investigators.
A MC stabilizer, comolyn was dissolved in sterile saline with a final concentration of 10 mg/mL. For the cromolyn treatment group, 2uL of cromolyn was administered intracerebroventricular (i.c.v) at 30 min before the CLP surgery and every 12h after surgery. The other group received 2uL of sterile saline.

According to previously described methods (Cui et al., 2018 (link)), under isoflurane (5% induction and 2% maintenance) anesthesia, the rats were implanted with electrodes for the polysomnographic recording of electroencephalograms (EEGs) and electromyograms (EMGs) and implanted with guide cannulas (O.D. 0.64 mm × I.D. 0.25 mm, C.C. 1.2 mm, RWD Life science Co., Ltd., Shenzhen, China) for drug administration into the lateral ventricle. After positioning the rats in a stereotaxic instrument, the guide cannula was implanted for the injection of STZ or vehicle (anterior/posterior, −0.8 mm; medial/lateral, −1.5 mm; dorsal/ventral, −3.5 mm). The cannulas and EEG electrodes were then fixed to the skull with dental cement, anchored by four stainless-steel screws. Two stainless-steel wire electrodes were placed in the dorsal neck muscles for EMG recordings. All electrodes were attached to a miniature connector. After surgery, the rats were placed on a heated pad, observed for at least 30 min, and then returned to their home cage. After surgical implantation, the rats were injected with penicillin for 3 days and allowed to recover for 7 days before the experiments. For habituation, the animals were connected to the recording apparatus at least 1 day before the experiments.

After being anesthetized with 1.2% isoflurane and fixed on the stereotaxic apparatus, mice were exposed of skull and cleaned with 10% hydrogen peroxide. During the surgery, the mice were maintained warm by a heating plate. After viruses were microinjected (described later in this section) into the LHA (AP: −1.6 mm, ML: 0.4 mm, DV: −4.5 mm) using a Nanoject III injector (Drummond Scientific) at a rate of 23 nL/min, an optical fiber (diameter, 300 μm, Inper, Hangzhou, China) was implanted into the ipsilateral LHb (AP: −1.6 mm, ML: −0.4 mm, DV: −2.5 mm) for optogenetic experiments, or a guide cannula (RWD, Inc.) for chemogenetic or pharmacological manipulations. To obtain EEG recording, three stainless‐steel screws were anchored to the skull as electrodes: the positive and negative electrodes on the left and right sides of the head, respectively, or vice versa (AP: −1.5 mm, ML: −1.5 mm) and a reference electrode at the back of the head (AP: −5.5 mm, ML: 0 mm). After surgery, mice were housed for recovery for 7 days. A total of 3 weeks was required for the expression of virus in the brain.