Selective Receptor Blockade in Neurotransmission

The following neurotransmitter/neuropeptide receptor blockers were used: cholecystonkinin-A receptor antagonist devazepide ([2mg/kg] in 5% DMSO PBS; Sigma)^{14 ,55} ; cocktail of the ionotropic glutamate receptor antagonist kynurenic acid (KA) ([150μg/kg] in PBS, stock made in 1M NaOH then diluted, pH 7.4; Sigma)^{14 ,56} and the metabotropic glutamate receptor antagonist DL-2-Amino-3-phosphonopropionic acid (AP-3) ([1mg/kg] in PBS, stock made in 1M NaOH diluted, pH 7.4; Sigma)^{14 ,57} ; and non-selective P2-purinoreceptor antagonist pyridoxalphosphate-6-azophenyl-2’,4’-disulfonic acid (PPADs) ([25mg/kg] in PBS; Sigma)^{33 (link),58 –60} . Following recording of a pre-inhibitor response, one inhibitor was delivered over one minute (devazepide and PPADS were delivered 10μL/g; KA/AP3 cocktail was delivered 20μL/g). Infusion of the selected sugar ligand was repeated for post-inhibitor recording after an incubation period: 5-8 minutes for devazepide and 3-5 minutes for KA/AP3 and PPADs.