Exercise Performance is not Influenced by a 5-HT Reuptake Inhibitor

Abstract

The purpose of the present study was to examine the effect of a selective serotonin (5-HT) reuptake inhibitor (SSRI) on exercise performance during a 90 min time trial. Eight well trained male cyclists (VO2max 68.1 +/- 9.5 ml/kg/min) performed three 90 min time trials at 65% Wattmax. Blood samples were collected via an indwelling venous catheter for adrenocorticotropin hormone (ACTH), prolactin (PRL), cortisol, catecholamines, growth hormone (GH) and beta-endorphins. The evening before and the morning of the time trials, the subjects ingested a capsule containing either placebo (lactose) or 20 mg Fluoxetine-HCI (Prozac, Ely Lilly Belgium). A double blind, randomized, placebo controlled, cross-over design was performed. Performance was not influenced by the SSRI. As expected, all blood parameters increased significantly during exercise (p < 0.05). During the SSRI trial most parameters were slightly lower but only significantly for endorphins and PRL (p < 0.05). The results demonstrate that performance is not influenced by an SSRI, although some plasma hormones indicate a central effect of the drug. Surprisingly, the increases in PRL and endorphins were lower during the SSRI trial, meaning that the hormonal modulation during exercise might be regulated by the interaction between neurotransmitters rather than by serotonin alone.

The Effects of Acute Dopamine Reuptake Inhibition on Performance

“…Changes in circulating PRL concentrations have previously been employed in defining serotonergic activity, but its reliability has been questioned (12). Ben-Jonathan (1) established that hypothalamic DA release inhibits PRL secretion from the anterior pituitary.…”

“…In a series of studies, Piacentini and colleagues (12,21,23,24) failed to modify performance of a 90 minutes time trial in normal ambient temperatures (18°C), through the manipulation of central neurotransmission. However, the authors detected different hormonal responses depending on the neurotransmitter system triggered by the reuptake inhibitor.…”

The Involvement of Brain Monoamines in the Onset of Hyperthermic Central Fatigue

“…Reduced exercise performance related to higher serotonin content in the preoptic area and the hypothalamus was also verified after a central blockade of angiotensinergic synapses . Serotonin reuptake inhibitors have also been widely used, with the purpose of investigating the relationship between the neurotransmitter and central fatigue (Meeusen et al, 2001;Pannier et al, 1995;Parise et al, 2001;Struder et al, 1998; W. M. Wilson et al, 1992). However, the results are contradictory and inconclusive.…”

Respostas de lactato, esfor&#231;o percebido, frequ&#234;ncia card&#237;aca, triptofano, prolactina e &#225;cidos graxos &#224; s&#233;rie de nata&#231;&#227;o na velocidade cr&#237;tica

“…Em exercícios de longa duração, a serotonina estimula a liberação de prolactina pela glândula hipófise e a [PRL] é considerada como um marcador de atividade seritoninérgica central (MEEUSEN et al, 2001;PITSILADIS et al, 2002). Ainda, no exercício de longa duração realizado com hipertermia, está associado a ocorrência de hiperprolactinemia, o que indica que os neurônios seritoninérgicos são ativados sob tais condições (MEEUSEN et al, 2001;PITSILADIS et al, 2002).…”

“…Em exercícios de longa duração, a serotonina estimula a liberação de prolactina pela glândula hipófise e a [PRL] é considerada como um marcador de atividade seritoninérgica central (MEEUSEN et al, 2001;PITSILADIS et al, 2002). Ainda, no exercício de longa duração realizado com hipertermia, está associado a ocorrência de hiperprolactinemia, o que indica que os neurônios seritoninérgicos são ativados sob tais condições (MEEUSEN et al, 2001;PITSILADIS et al, 2002). Uma limitação dos estudos com seres humanos, devido às questões éticas, é a incerteza em relação à captação de triptofano cerebral, o que torna impossível de avaliar se alterações nos níveis da [TRP] tem o efeito esperado no equilíbrio do triptofano no cérebro (NYBO;SECHER, 2004).…”