Elsevier

Psychoneuroendocrinology

Volume 36, Issue 10, November 2011, Pages 1530-1539
Psychoneuroendocrinology

Prolactin in response to acute psychosocial stress in healthy men and women

https://doi.org/10.1016/j.psyneuen.2011.04.007Get rights and content

Summary

Background

Serum levels of the anterior pituitary hormone prolactin have been reported to increase in response to different types of psychological stressors in humans. However, experimental laboratory stress studies investigating the acute response of prolactin to psychological stress show inconsistent results as increased, as well as decreased or unchanged levels of prolactin have been reported.

Objective

The aim of this study was to investigate the effect of acute psychosocial stress on serum concentrations of prolactin in healthy men and women and possible sex differences.

Method

Thirty men and 15 women (age 30–50 years) underwent Trier Social Stress Test (TSST), a tool for investigating psychobiological stress responses in a laboratory setting. Blood samples were collected before and directly after the stress test and after 30 min of recovery.

Results

We observed significantly elevated prolactin levels – along with significantly increased plasma adrenocorticotropic hormone (ACTH), serum cortisol, heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) – in response to the stressor. The prolactin response pattern did not differ between men and women, but there was some indication that women might have higher magnitude of response. Large individual differences regarding the magnitude of response were seen in general. The magnitude of the prolactin response was significantly related to the magnitude of the response of the hypothalamic–pituitary–adrenal (HPA) axis and, to some extent, the cardiovascular responses, indicating that individual differences in prolactin response in healthy men and women are dependent on the general physiological stress activation. In women, the magnitude of response was also related to estradiol level.

Conclusion

Prolactin does increase in response to psychosocial stress, however, with large individual variation in magnitude of response. The pattern of prolactin response does not differ between men and women. However, there was some indication that women might have higher magnitude of increase than men, and that the magnitude of response in women was dependent on estradiol levels, and this needs to be further studied.

Introduction

Prolactin is a peptide hormone mainly synthesized and secreted by lactotrope cells in the anterior pituitary gland. The secretion is primary regulated by dopamine neurons, which have an inhibitory effect. Prolactin was discovered over 80 years ago and was given its name because of its ability to promote lactation in response to the suckling stimulus of the baby. Now it is known that prolactin is a multifunctional hormone, with over 300 biological activities including functions in reproduction, homeostasis, and the immune system (Freeman et al., 2000). Prolactin has been reported to increase in response to different types of psychological stressors in humans (Schedlowski et al., 1992, Theorell, 1992, Theorell et al., 1993, Grossi et al., 1999, Sonino et al., 2004, Uhart et al., 2006). The physiological importance of stress-induced prolactin increase is not clear, but prolactin has been suggested to have a protective role against the damage caused by stress (Drago et al., 1989, Dorshkind and Horseman, 2001), possibly through immunohancement (Black, 1994, Fomicheva et al., 2004) and to be a regulator of the stress response (Torner et al., 2001). Prolactin is thus considered to be a stress hormone. However, experimental laboratory stress studies investigating the acute response of prolactin to psychological stress show inconsistent results. Increased (Meyerhoff et al., 1988, Kirschbaum et al., 1993, Uhart et al., 2006, Chong et al., 2008) as well as decreased (Gerra et al., 2000, Gerra et al., 2001, Atanackovic et al., 2002, Heesen et al., 2002, Rouach et al., 2007) or unchanged (Gerra et al., 2000, Munro et al., 2005) prolactin levels in response to psychosocial stress have been reported. Studies on acute psychosocial stress and prolactin have been predominantly conducted on men; thus, knowledge about prolactin response in women is more limited. The aim of this study was to investigate the effect of acute psychosocial stress on serum concentrations of prolactin in healthy men and women, and possible sex differences, by using the Trier Social Stress Test (TSST), a well-established tool for investigating psychobiological stress responses in a laboratory setting.

Section snippets

Participants

Forty-five healthy subjects (30 men and 15 women), aged 30–50 years (mean age 39 years, SD 5.7 years), were included in the study. The subjects were recruited from a cohort study, surveying psychosocial work environment and health, and through advertising in a local daily newspaper. To be included in the study, subjects had to be between 30 and 50 years of age, and only individuals reporting “no stress at all” or “very little stress” on a single perceived stress item (Elo et al., 2003) were

Study sample

Table 1 reports the baseline characteristics of the participants. In this group of 30 men and 15 women, there were no sex differences in age, nicotine use or scores on the anxiety, depression or burnout scales. As expected, prolactin levels were higher in the female subjects. BMI were significantly higher in the male subjects and heart rate was significantly higher in the female subjects. Age did not correlate with baseline prolactin levels in men (r = −0.179, p = 0.344) or in women (r = 0.245, p = 

Stress-induced increase of prolactin in both men and women

This study investigated the response of prolactin to acute psychosocial stress in healthy men and women. We observed significantly elevated prolactin levels – along with significantly increased ACTH, cortisol, heart rate, systolic blood pressure, and diastolic blood pressure – in response to the stressor. The prolactin concentration increased directly after the stress test as compared to before on average by 88% in men and 85% in women. As mentioned previously, men have predominantly been

Conclusions

We conclude that prolactin does increase in response to acute psychosocial stress and that the pattern of prolactin response does not differ between men and women. However, there was some indication that women might have higher magnitude of increase than men, but this needs to be elucidated in future studies with larger sample. Furthermore, the results show a large inter-individual variation in general and it was seen that the magnitude of the prolactin response is related the magnitude of the

Role of funding source

This study was funded by a grant from the Swedish government. The funding source had no role in study design; in the collection, analysis and interpretation of data; in the writing of the report or in the decision to submit the paper for publication.

Conflict of interest statement

There are no conflicts of interest for any of the authors.

Acknowledgements

We would like to express our gratitude toward the participants in the study and the research nurses Karin Nygren and Anna Palmgren for their invaluable help with performing stress test and blood sampling. We would also like to thank the people who served as committee members during the TSST.

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