The benefits and drawbacks of nicotine exposure in the cortex and hippocampus of old rats.
Nicotine is the main alkaloid of tobacco and possesses well-established stimulant effects. Previous reports show that nicotine at low doses improves memory functions, while high doses impair memory. This study aims to analyze the effects of nicotine (NIC) on inhibitory avoidance task and on DNA damage, reactive oxygen species (ROS) concentration, total antioxidant capacity, and lipid peroxidation in cortex and hippocampus of old rats. Male Wistar rats of 24-26 months old (620-700g) were exposed i.p. to two doses (0.3 and 1mg/kg) of NIC daily during 9 days. The treatment NIC 0.3 enhanced long-term memory (p<0.05), whereas NIC 1 improved both short and long-term memories (p<0.05). DNA damage was observed only in hippocampus (p<0.05) after NIC 1 exposure. A similar result was obtained for ROS: higher levels were detected at NIC 1 treatment in hippocampus (p<0.05). No alterations in the total antioxidant capacity were verified after NIC exposure (0.3 and 1mg/kg) in both tissues (p>0.05). Finally, evidence of oxidative damage was observed in terms of lipid peroxides levels, being higher at NIC 1 in hippocampus (p<0.05). Overall the results indicate that deleterious effects paralleled the improved short and long-term memories at the highest NIC dose, since augmented DNA damage, ROS concentration and lipid peroxides levels were registered.
Barros
D M
DM
Departamento de Ciências Fisiológicas, Fundação Universidade Federal do Rio Grande (FURG) (96201-900), Rio Grande, RS, Brazil. barrosdm@yahoo.com.br
Galhardi
F G
FG
Ribas Ferreira
J L
JL
Guterres
L B
LB
Dickel
O
O
Geracitano
L A
LA
Izquierdo
I
I
Monserrat
J M
JM
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001362:Avoidance Learning / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects* / Q000254:growth & development*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D016166:Free Radical Scavengers / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects* / Q000254:growth & development*; D015227:Lipid Peroxidation / Q000187:drug effects; D008054:Lipid Peroxides / Q000378:metabolism; D008568:Memory / Q000187:drug effects; D008570:Memory, Short-Term / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology* / Q000633:toxicity*; D018722:Nicotinic Agonists / Q000494:pharmacology* / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
D000975:Antioxidants; D016166:Free Radical Scavengers; D008054:Lipid Peroxides; D018722:Nicotinic Agonists; D017382:Reactive Oxygen Species; D009538:Nicotine