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Lower levels of prepulse inhibition of startle response in pregnant women compared to postpartum women
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
2008 (English)In: Psychoneuroendocrinology, ISSN 0306-4530, E-ISSN 1873-3360, Vol. 33, no 1, 100-107 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: During the postpartum period, estradiol and progesterone levels decline from very high levels during late pregnancy to low levels within 48h of parturition. This period is associated with dysphoric states such as the postpartum blues. Animal studies have suggested an enhanced acoustic startle response and deficient prepulse inhibition (PPI) of startle response following progesterone withdrawal and during the postpartum period. The aim of the current study was to compare acoustic startle response and PPI in healthy third trimester pregnant women and healthy postpartum women. METHODS: Twenty-eight healthy pregnant and 21 healthy postpartum women (examined between 48h and 1 week after delivery) were recruited for the study. In addition, to evaluate the time-course of postpartum changes 11 early postpartum women (examined within 48h following delivery) were included in the study. The eyeblink component of the acoustic startle reflex was assessed using electromyographic measurements of m. Orbicularis Oculi. Twenty pulse-alone trials (115dB 40ms broad-band white noise) and 40 prepulse-pulse trials were presented. The prepulse stimuli consisted of a 115dB 40ms noise burst preceded at a 100ms interval by 20ms prepulses that were 72, 74, 78 or 86dB. RESULTS: Pregnant women exhibited lower levels of PPI compared to late postpartum women, p<0.05. There was no difference between pregnant women and postpartum women examined within 48h of delivery. There was no difference in startle response or habituation to startle response between pregnant women and either of the two groups of postpartum women. CONCLUSION: Healthy women display lower levels of PPI during late pregnancy when estradiol and progesterone levels are high compared to the late postpartum period when ovarian steroid levels have declined.

Place, publisher, year, edition, pages
2008. Vol. 33, no 1, 100-107 p.
Keyword [en]
Prepulse inhibition, Startle response, Pregnancy, Postpartum, Estradiol, Progesterone
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-97754DOI: 10.1016/j.psyneuen.2007.10.005ISI: 000253027800011PubMedID: 18037247OAI: oai:DiVA.org:uu-97754DiVA: diva2:172812
Available from: 2008-11-14 Created: 2008-11-14 Last updated: 2011-01-12Bibliographically approved
In thesis
1. Hormones, Mood and Cognition
Open this publication in new window or tab >>Hormones, Mood and Cognition
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Ovarian steroid hormones are neuroactive steroids with widespread actions in the brain, and are thus able to influence mood, behavior and cognition.

In this thesis the effects of progesterone withdrawal and the direct effects of the progesterone metabolite allopregnanolone are evaluated.

Allopregnanolone, through binding to the GABAA receptor complex, enhances inhibitory neurotransmission, thus exerting anxiolytic, sedative and antiepileptic effects.

The acoustic startle response (ASR) is a withdrawal reflex evoked by sudden or noxious auditory stimuli, and can be measured in humans as an eye blink. ASR is significantly increased in several anxiety disorders, and notably also during progesterone withdrawal.

Sensorimotor gating can be assessed by measuring prepulse inhibition of the startle response (PPI). The CNS circuits regulating PPI are sensitive to hormone fluctuations. GABAergic drugs are involved in cognitive impairment and animal studies have indicated that allopregnanolone may inhibit learning.

The main purpose of this research was to evaluate the behavioral effects of progesterone withdrawal on the startle response and sensorimotor gating in PMDD patients and healthy controls, in healthy third trimester pregnant women and healthy postpartum women. A second aim was to evaluate allopregnanolone effects on memory and cognition in healthy women and also on the startle response and PPI.

We found that PMDD patients have an increased startle response across the menstrual cycle and a deficiency in sensorimotor gating during the late luteal phase.

Ovarian steroids affect sensorimotor gating; pregnant women have lower levels of PPI than late postpartum women. Acutely administered allopregnanolone did not affect the ASR or PPI. Allopregnanolone impairs episodic memory in healthy women.

In conclusion, our studies suggest that ovarian steroids, including allopregnanolone, do not influence the startle response. Ovarian steroids affect sensorimotor gating; pregnancy, a condition with high levels of ovarian steroids, suppresses PPI. Theoretically, the variability in PPI across reproductive events is due to effects mediated by the progesterone or estradiol receptors but is not mediated by allopregnanolone. PMDD patients display decreased PPI during the late luteal phase, suggesting underlying pathophysiology in common with other anxiety disorders. The most vulnerable memory system, the episodic memory, is impaired by the allopregnanolone in healthy women.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 91 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 394
startle response; prepulse inhibition; premenstrual dysphoric disorder; menstrual cycle; pregnancy; postpartum period; episodic memory; semantic memory; working memory; progesterone; estradiol; allopregnanolone.
National Category
Clinical Science
urn:nbn:se:uu:diva-9365 (URN)978-91-554-7332-7 (ISBN)
Public defence
2008-12-05, Rosénsalen, Uppsala University Hospital, Entrance 95/96, Uppsala, 13:15
Available from: 2008-11-14 Created: 2008-11-14Bibliographically approved

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