Ondansetron hydrochloride dihydrate

We purchased common salts and 1-(3-Chlorophenyl) biguanide hydrochloride (mCPBG); gabazine; 1,2-bis(2-aminophenoxy) ethane-N,N,N,N-tetraacetic acid (BAPTA); SCH50911; 6,7-dinitroquinoxaline-2,3-dione (DNQX); tetrodotoxin (TTX); strychnine; SB200646 hydrochloride (SB200646); ritanserin (RIT); ondansetron hydrochloride dihydrate (OND); and 5-HT hydrochloride (5-HT) from Sigma-Aldrich Chemical Company (St Louis, MO, USA). Citalopram hydrobromide, WAY100635, and 1-(3-Chlorophenyl) piperazine hydrochloride (mCPP) from Tocris Bioscience (Ellisville, MO, USA).

For 5-HT3R antagonism, the selective 5-HT3R antagonist Ondansetron (OND; ondansetron hydrochloride dihydrate, Sigma-Aldrich, O3639) was dissolved in sterile saline in a concentration of 2 μg/μl. For 5-HT1aR agonism, the selective agonist Buspirone (BUS, buspirone hydrochloride; Sigma-Aldrich, B7148) was dissolved in sterile saline to a concentration of 10 μg/μl. Pilot studies testing 1, 3 and 5 mg/kg BUS and 0.3, 1 and 3 mg/kg OND showed that 3 mg/kg BUS and 3 mg/kg OND were most promising in preventing acute hypersensitivity associated with neonatal repetitive needle pricking (see Figure 1), without adverse side effects (including body weight changes or mortality). Based on pup's body weight per postnatal day, 50 μl solution containing OND (3 mg/kg) or BUS (3 mg/kg) was injected sc. twice daily (at 9 a.m. before the 1st needle prick and 11 a.m. before the 3 rd needle prick). TC and NP animals received an equivalent volume of saline.