title: The impact of age on emotional and cognitive behaviours triggered by experimental neuropathy in rats.
abstract: Chronic pain syndromes encompass several clinical entities that frequently affect the individuals' emotional and cognitive behaviours which, in turn, can also alter pain perception. Additionally, both pain perception and motivational-affective behaviours change with increasing age. In order to evaluate the influence of age upon the interaction between chronic pain and affective/cognitive behaviours, 3-, 10- and 22-month-old rats with 1 month neuropathy (spared nerve injury, SNI model) were compared with age-matched sham-operated controls in the open field (OF; locomotor and exploratory behaviours), elevated plus-maze (EPM; anxiety-like behaviour), forced swimming (FST; depressive-like behaviour), working memory water maze (WM; spatial short-term memory), Morris water maze (MWM; spatial reference memory) and spatial reversal (behavioural flexibility) tests. Locomotor and exploratory activities decreased steadily with age and were further reduced by SNI. Aging was associated with increased anxiety-like behaviour, which was potentiated by SNI in both 3- and 22-month-old rats. The performance in the FST was affected by SNI but only in mid-aged animals. Cognitive performances in the MWM and spatial reversal tests deteriorated with age; however, the SNI lesion was only detrimental in the reversal task to mid-aged animals. Our data demonstrate that the influence of neuropathic pain on affective and cognitive behaviours is age dependent and varies with the behavioural domain that is tested. Importantly, mid-aged animals seem to be more susceptible to depression and cognitive deterioration associated to chronic pain than young and old groups.
authors.affiliation: Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Hugo
authors.initials: H
authors.lastname: Leite-Almeida
authors.forename: Luis
authors.initials: L
authors.lastname: Almeida-Torres
authors.forename: Ana Raquel
authors.initials: AR
authors.lastname: Mesquita
authors.forename: Antti
authors.initials: A
authors.lastname: Pertovaara
authors.forename: Nuno
authors.initials: N
authors.lastname: Sousa
authors.forename: João José
authors.initials: JJ
authors.lastname: Cerqueira
authors.forename: Armando
authors.initials: A
authors.lastname: Almeida
mesh_terms: D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D003072:Cognition Disorders / Q000209:etiology*; D004195:Disease Models, Animal; D004644:Emotions / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008570:Memory, Short-Term / Q000502:physiology; D009483:Neuropsychological Tests; D010147:Pain Measurement / Q000379:methods; D010523:Peripheral Nervous System Diseases / Q000150:complications* / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D013497:Sural Nerve; D013550:Swimming / Q000502:physiology