Ejercicio E Hipocompo

Behavioural Brain Research 176 (2007) 362–366

Short communication

The effects of forced exercise on hippocampal plasticity in the rat: A comparison of LTP, spatial- and non-spatial learning
´ Rachel M. O’Callaghan a,b , Robert Ohle b , Aine M. Kelly a,b,∗
a

Department of Physiology, School of Medicine, University of Dublin, Trinity College, Dublin 2, Ireland b Trinity College Instituteof Neuroscience, University of Dublin, Trinity College, Dublin 2, Ireland Received 11 August 2006; received in revised form 11 October 2006; accepted 13 October 2006 Available online 20 November 2006

Abstract Physical activity may have the potential to improve cognitive function. Here we show that forced treadmill-running results in selective improvements in hippocampal plasticity. Rats thatunderwent exercise training demonstrated enhanced expression of long-term potentiation in dentate gyrus and enhanced object recognition learning. Spatial learning in the Morris watermaze was unaffected by exercise. These changes were associated with an increase in expression of brain-derived neurotrophic factor in the dentate gyrus. © 2006 Elsevier B.V. All rights reserved.
Keywords: Exercise;BDNF; Hippocampus; Spatial learning; LTP; Object recognition

1. Introduction The positive effects of exercise on many physiological systems, including the central nervous system, are well-established. Exercise-induced improvements in learning and memory have been directly associated with improved neurogenesis, an increase in activity-dependent synaptic plasticity and altered gene expression[8,9,23]. Many of these improvements have been observed in the hippocampus, a highly plastic structure located in the medial temporal region of the brain that is vital to activity-dependent learning and memory [17]. The reported forms of hippocampal-dependent learning are manifold, but the majority of studies exploring the effects of exercise on hippocampal plasticity have assessed long-termpotentiation (LTP), a well-recognized cellular analogue of learning and memory, and spatial learning. There is evidence to suggest that neurogenesis, an increase in which has been linked to exercise, may be necessary only in specific types of hippocampal-dependent learning. Shors and colleagues [22] reported that treatment of rats with an antimitotic agent reduced fear acquisition after exposure to a tracefear conditioning paradigm but did not affect contex∗ Corresponding author at: Department of Physiology, School of Medicine, University of Dublin, Trinity College, Dublin 2, Ireland. Tel.: +353 16083794; fax: +353 16793545. ´ E-mail address: aikelly@tcd.ie (A.M. Kelly).

tual fear conditioning, spatial navigation learning or exploration in the elevated plus maze. To our knowledge, no research hasexplored the effects of exercise on the form of recognition memory assessed in this study [13]. Both voluntary and forced exercise protocols have been used to explore the effect of exercise on brain function. Although it has been argued that forced exercise may better simulate some human exercise regimes, it has been suggested that it may abrogate the positive effects observed with voluntaryexercise by increasing stress levels. Despite this theory, research has shown an improvement in cognitive function following treadmill exercise [2]. Moreover, it has been proposed that exercise has the ability to overcome stress-induced effects of corticosterone on expression of brain-derived neurotrophic factor (BDNF) [1]. Neurotrophins are a family of proteins that play pivotal roles in both thedeveloping nervous system and the adult brain. BDNF is the most widely-distributed neurotrophin in the brain and has been cited as a major regulator of synaptic plasticity. BDNF infusion has been shown to enhance LTP in the rat dentate gyrus [18], while transgenic mice have been used to demonstrate that BDNF plays an important functional role in the expression of LTP in the hippocampus [16]. It has...