Posttraining D1 receptor blockade impairs odor conditioning in neonatal rats.

Abstract

Rat pups that were exposed to a novel anise odor paired with tactile stimulation (stroking the skin with a paint brush) received injections of either saline or the dopamine D1 receptor antagonist (+/-)-SKF 83566 (0.1 mg/kg) before conditioning or immediately after conditioning. Animals that received the drug either before or after training showed less approach to the conditioned odor during the testing period 24 hr later than did animals that received the vehicle. Posttraining administration of the D2 receptor antagonist spiperone (0.1 mg/kg) did not affect subsequent approach to the conditioned odor, suggesting a selective effect of D1 receptor blockade. The impairment in learning by the administration of (+/-)-SKF 83566 before conditioning was reversed by the injection of the dopamine receptor agonist apomorphine (0.1 mg/kg) immediately after conditioning. Posttraining D1 receptor activation appears necessary for normal odor conditioning in rat pups.

Dopamine receptor subtypes modulate olfactory bulb γ-aminobutyric acid type A receptors

“…Post-training D1 receptor blockade leads to impaired odor conditioning in neonatal rats (34). Likewise, odor-detection performance of adult animals is reduced on administering a D2 agonist (35).…”

Examining the role of endogenous opioids in learned odor–stroke associations in infant rats

“…Specifically, human infants can associate tactile stimulation with an odor during the first few hours of life (Sullivan et al, 1991), indicative that the neural mechanisms necessary for affective learning and memory are already present and functional. Similar associative conditioning has been well documented in rat neonates (Dominguez, Lopez, & Molina, 1999;McLean, Darby-King, Sullivan, & King, 1993;Sullivan & Hall, 1988;Weldon, Travis, & Kennedy, 1991). Neurochemical systems involved in mediating the neonate's response to touch include cholecystokinin (Weller & Feldman, 2003), opioids (Panksepp, Herman, Vilberg, Bishop & DeEskinazi, 1980), oxytocin (Insel, 1997;Nelson & Panksepp, 1996), and serotonin (McLean et al, 1993), although norepinephrine (NE, Sullivan & Wilson, 1994) has a particularly prominent role in mediating learned odor-stroke associations in rat neonates.…”

Serotonergic influence on olfactory learning in the neonate rat

“…For the odor/stroke paradigm, the pup was placed on the peppermintscented bedding under a lamp (30°C) and stroked using a soft brush (unconditioned stimulus) vigorously every other 30s for 30s during the 10-rain conditioning period. The stroking was strong enough to elicit activity in the pup and has been used by others to mimic maternal behavior (Pedersen et al, 1982;Weldon, Travis, & Kennedy, 1991). For the odor only paradigm, the pup was placed on the peppermintscented odor under a lamp (30°C) for the same 10-min period but received no stroking stimulus.…”