p. injection and at 7 μg/kg for intracisternal injection. Sulpiride was used at 50 mg/kg (Melo et al. 2013). Drugs administration The analgesic effects of bromocriptine, a drug used as PD therapy (Calne et al. 1974), were studied by injecting the drug both intracisternally (Fischer et al. 2005) and intraperitoneally. Bromocriptine is known to cross the blood brain barrier (Vautier

et al. Inhibitors,research,lifescience,medical 2009). The animals were briefly (<3 min) anesthetized with 2% halothane using a mask and received intracisternal administration of bromocriptine (7 μL/kg dissolved in 5 μL vehicle) or the vehicle alone (5 μL of 0.9% saline). Following recovery (<2 min), the rats were placed in the observation field under a red light for a 40-min test period. Gentle air puffing (1 sec duration) was applied every 3 min (Alvarez et al. 2009). For the intraperitoneal injection, bromocriptine was used at a dose of 1 mg/kg and its effect was studied for a 6-h test period. Finally, Inhibitors,research,lifescience,medical the antagonist action of sulpiride on the bromocriptine-induced Inhibitors,research,lifescience,medical analgesic effect was assessed by administrating this compound (50 mg/kg) 90 min prior to the intracisternal injection of bromocriptine. Behavioral testing The rats were adapted to the observation field and red light for 30 min each day for 9 days prior to the beginning of behavioral testing. During this period, the experimenter reached into the cage

to apply gentle air puffing on the animals’ faces Inhibitors,research,lifescience,medical (see below). For each behavioral test, the rats were placed in the observation field (24 × 35 × 18 cm) under red light for a 30-min period. Gentle air puffing (five air puffs, with a 5-sec time lag Enzastaurin cost between each air puff) was applied by an experimenter (Dieb and Hafidi 2013) every 3 min and repeated 10 Inhibitors,research,lifescience,medical times, alternatively on either side of the vibrissal pad, using a calibrated pump. Stimulation

was carried out when the rat was in a sniffing/no locomotion state: with four paws placed on the ground, neither moving nor freezing (Alvarez et al. 2009). The distance to the target from which the stimulus was applied varied from 2 to 5 cm. The tip of the pump was moved toward the target from behind the animal so that it could not see it. Each series of stimulations consisted of five air puffs applied every Terminal deoxynucleotidyl transferase 10 sec. The behavioral responses were observed and quantified according to the analysis method proposed by Vos et al. (1994). Nociceptive responses to gentle air puffing consisted of one or more of the following elements: (Altier and Stewart 1999) detection, the rats turn head toward stimulus; (Alvarez et al. 2009) withdrawal reaction, the rats turn head away or pull it briskly backward when stimulation is applied (a withdrawal reaction is assumed to include a detection element preceding head withdrawal and therefore consists of two response elements); (Ansah et al.