Neonatal handling reduces emotional reactivity and susceptibility to learned helplessness. Involvement of catecholaminergic systems.
Environmental circumstances during the neonatal period are critical for the establishment of adult responses to stressful environmental situations. As these responses are underpinned by adaptations in the functioning of brain neurotransmitter systems, the present study was designed to assess the mediation of noradrenergic and dopaminergic systems in the long-lasting effects of neonatal handling on both emotionality and learned helplessness behaviour. Animals received either prazosin, propranolol, haloperidol or saline before infantile handling. When the animals were 2 months old, they were subjected first to an open field test and then to the learned helplessness paradigm. Non-treated handled animals exhibited lower emotional reactivity and reduced susceptibility to helplessness compared to non-treated non-handled rats. The results suggest that noradrenergic, but not D2-dopamine receptor systems mediate the influence of neonatal handling on the acquisition of learned helplessness in the adult. Only beta-adrenoceptors appear to play a role in emotional responsiveness.
Tejedor-Real
P
P
Department of Neurosciences, School of Medicine, University of Cádiz, Spain. tejedor.real@uca.es
Costela
C
C
Gibert-Rahola
J
J
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004924:Escape Reaction / Q000187:drug effects; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D006380:Helplessness, Learned; D008297:Male; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010812:Physical Stimulation; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017983:Receptors, Catecholamine / Q000187:drug effects* / Q000502:physiology
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D018492:Dopamine Antagonists; D018377:Neurotransmitter Agents; D017983:Receptors, Catecholamine; D011433:Propranolol; D006220:Haloperidol; D011224:Prazosin