2.4 Intranucleus accumbens (NAc) infusions
Briefly, C57BL/6J mice were anaesthetized with 0.5% pentobarbital
sodium solution (50 mg·kg-1, i.p.) and fixed in a
stereotaxic apparatus (Kopf, Tujunga, CA), with the anaesthetizing
effects evaluated by muscle relaxation, slow corneal reflex, and no skin
pinch reaction. The scalp was cut, and the skull was exposed using 75%
alcohol and 1% H2O2. The cannulas were
implanted into the bilateral NAc according to bregma: anteroposterior, +
1.5mm; mediolateral, + 1.0mm; dorsoventral, - 4.5mm(B Jiang et al.,
2013). The cannula was cemented in place, and the incision was sutured.
The animals were allowed to recover for at least 5 days after surgery.
Osmotic minipumps were designed to deliver bilateral microinjection of
different amounts of D-serine (2ug/perside ;5ug/perside), K252a (5
ug/perside), fluoxetine (5 ug/perside), or saline (0.9%) into the NAc
daily for 14 days. Each osmotic minipump was attached to a brain
infusion cannula. A total volume of 1.0 uL was infused into each side
over 15 min, and the injection syringe was maintained in place for an
additional 5 minutes to limit reflux along the injection track. In some
experiments, a nonspecific tyrosine kinase inhibitor, K252a
(5ug/perside), was co-infused bilaterally with D-serine, K252a was
infused bilaterally 20 minutes before infusion of D-serine.