Effects of pre- and postnatal exposure to 5-methoxytryptamine and early handling on an object-place association learning task in adolescent rat offspring.
A reduction in 5-HT1A receptor response enhances learning and memory performance in rats. Pre- and postnatal treatment with 5-methoxytryptamine (5MT), a non-selective serotonergic agonist, and early handling, reduce the number of 5-HT1A receptors in neonatal and pre-pubertal rat progeny. The aim of this study was to investigate in adolescent male rats the consequences of pre- and postnatal treatment with 5MT and its interaction with early handling on an object-place association learning task, the "Can test", a motivated, non-aversive, spatial/object discrimination task. Results show that a single daily injection of 5MT from gestational days 12 to 21 (1 mg/kg s.c.) and from postnatal days 2 to 18 to pups (0.5 mg/kg s.c.), increases the level of activity and the number of correct responses, and decreases the number of reference memory errors in the progeny as adolescent, compared to vehicle-treated rats. Similar effects are observed following a daily, brief, maternal separation of the pups from postnatal days 2 until 21. Furthermore, when 5MT-treated rats underwent to early handling procedure, the effects induced by 5MT increased handling-induced facilitation of the object-place association. These results suggest that pre- and postnatal treatment with 5MT enhances learning in the "Can test", probably due to a reduction in 5-HT1A receptors in the hippocampus. Whether the potentiation exerted by pre- and postnatal 5MT on early handling effects may be related to a further damping of 5-HT1A receptor response is not yet assessed; however, our data demonstrate that this association is able to induce long-term facilitative effects on spatial learning performance in a non-aversive spatial/object discrimination task in the adolescent rat offspring.
Cannizzaro
Carla
C
Dipartimento di Scienze Farmacologiche, Università di Palermo, V. Vespro 129, 90127 Palermo, Italy. psycho@unipa.it
Plescia
Fulvio
F
Gagliano
Mauro
M
Cannizzaro
Gaspare
G
Provenzano
Giuseppa
G
Mantia
Giacoma
G
Cannizzaro
Emanuele
E
D008735:5-Methoxytryptamine / Q000494:pharmacology*; D000818:Animals; D001245:Association Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D005260:Female; D006234:Handling, Psychological; D016014:Linear Models; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013037:Spatial Behavior / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
D017366:Serotonin Receptor Agonists; D008735:5-Methoxytryptamine