Effect of a 12-Month Randomized Clinical Trial of Exercise on Serum Prolactin Concentrations in Postmenopausal Women

Abstract

Prolactin is associated with an increased risk of postmenopausal breast cancer; however, few modifiable factors are known to reduce prolactin concentrations. Therefore, we examined the effect of a 12-month moderate-intensity exercise intervention on serum prolactin concentrations as a secondary end point (primary end points were estrogens and androgens). We randomly assigned 173 postmenopausal women who were sedentary, overweight (body mass index >24 kg/m 2 , body fat >33%), ages 50 to 75 years, and not using hormone therapy to an exercise intervention or stretching control group. The intervention was facility-and homebased (45 min, 5 days/wk moderate-intensity sports/recreational exercise). One hundred and seventy (98%) women completed the study. Prolactin concentrations were similar at baseline (P = 0.25, geometric mean exercisers = 6.9 and controls = 7.5 ng/mL). Overall, the intervention was not associated with changes in prolactin concentrations between exercisers and controls at 3 months (P = 0.46) or 12 months (P = 0.29). The intervention effect did not vary by baseline age, body mass index, parity, or change in percent body fat during the intervention. Among exercisers, there was a significant difference in prolactin concentrations by change in fitness (VO 2 max) between baseline and 12 months. Exercisers whose VO 2 max changed by <5% had a 5% increase in prolactin concentrations, whereas those who increased their VO 2 max by 5% to 15% and >15% had a 11% (P = 0.03) and 7% (P = 0.01) decrease in prolactin concentrations, respectively. Although the exercise intervention had little effect on prolactin concentrations overall, increasing physical fitness was associated with reduced prolactin concentrations among postmenopausal women. (Cancer Epidemiol Biomarkers Prev 2007;16(5):895 -9)

Antidepressant use and circulating prolactin levels

“…Continuous AD use was likely occurring in many of these participants, but the exact number is unknown. It is possible that SSRIs may have an acute effect on circulating prolactin levels, similar to reported short-term changes in prolactin associated with physical activity [39], but that these effects are not sustained with long-term use, which represents the experience of the majority of SSRI users in NHS and NHS2. We were unable to evaluate this hypothesis in the present study, but additional research would be warranted to fully understand both the short- and long-term implications of SSRI use on prolactin levels.…”

Physical activity does not alter prolactin levels in post-menopausal women: results from a dose-response randomized controlled trial

“…In the study by Reding et al [4], baseline BMI did not alter the treatment effect. In the study by Tworoger et al [3], change in percent body fat did not mediate the intervention effect however, women in the exercise group who increased their VO 2 max by >5% had a statistically significant reduction in prolactin levels.…”

“…Previous studies comparing 12 months of moderate-intensity aerobic exercise to no exercise have reported null effects on prolactin levels [3, 4]. Similarly, the results from these previous trials remained unchanged when exercise adherence, measured as minutes of exercise per day, was considered [3, 4].…”

“…Increased circulating levels of prolactin have been associated with increased risk of both in situ and invasive breast cancer [2]. Two previous exercise intervention trials in post-menopausal women did not observe changes in prolactin levels in response to moderate physical activity [3, 4] compared to controls. As part of the Breast cancer and Exercise Trial in Alberta (BETA) we investigated: 1) the effects of increased levels of moderate to vigorous physical activity (MVPA) on levels of prolactin and 2) whether a higher level of activity led to larger changes in prolactin levels.…”

Physical Activity and its Relation to Cancer Risk: Updating the Evidence

“…To date, biologic mechanisms by which physical activity can influence cancer have not been established; however several mechanisms through which physical activity exerts effects have been proposed (Feig et al, 1994;Toyokuni et al, 1995;Hoffman-Goetz et al, 1998;Shephard and Shek, 1998;Rundle, 2005;Garofalo and Surmacz, 2006;Kay and Sing, 2006;Kruk and AboulEnein, 2006;2007;Szlosarek et al, 2006;Wetmore and Ulrich, 2006;Tworoger et al, 2007a;WCRF/AICR, 2007;Coyle, 2008;Renehan et al, 2008;Neilson et al, 2009;Thompson et al, 2009;Verna and Montgomery, 2009;Friedenreich et al, 2010a;Kruk, 2011;Lynch et al, 2011;Heikkila et al, 2013) and examined in randomized controlled trials (McTiernan et al, 2005;Abrahamson et al, 2007;Tworoger et al, 2007b;Hawkins et al, 2008;Balducci et al, 2010;Campbell et al, 2010;Friedenreich et al, 2010b;2010c;Reding et al, 2011).…”