Document Detail

Peripartum plasticity within the hypothalamo-pituitary-adrenal axis.
MedLine Citation:
PMID:  11589125     Owner:  NLM     Status:  MEDLINE    
The hypothalamo-pituitary-adrenal (HPA) axis plays important roles in the adaptive changes in physiology that occur during pregnancy and lactation. Although the axis still exhibits a pulsatile pattern of secretion, the normal diurnal rhythm of pulse amplitude is lost during lactation, such that mean basal levels remain constant throughout the day. In addition, the peripartum period is associated with a remarkable plasticity in stress-induced HPA activity, in that the increase of HPA activity normally seen in response to either physical or psychological stresses in the non-reproductive state become severely attenuated or absent in the lactating animal. This stabilization of both basal and stress-induced HPA activity may be important for maintaining a constant endocrine environment, thereby preventing any programming effects on the developing offspring. Attenuation of the stress response is initiated in late pregnancy and is temporally associated with luteolysis, indicating possible steroid hormone involvement. Indeed, mimicking the luteolytic changes in oestrogen and progesterone levels in non-pregnant animals induces a similar attenuation of the stress response. Furthermore down-regulation of the stress response is, at least in part, centrally mediated since in the period following luteolysis rats will show a decreased level of stress-induced neuronal activation of the PVN, as measured by the expression of either c-fos or CRH mRNAs. Persistence of this adapted state is dependent upon the continued suckling stimulus, as removal of the offspring litter rapidly leads to resumption of HPA responses to and the appearance of an exaggerated diurnal rhythm. The underlying mechanisms responsible for this stress hyporesponsiveness may include plasticity of noradrenergic and oxytocin pathways. In view of its role in other reproductive behaviors, a stress-inhibiting effect of oxytocin may reflect a more widespread co-ordinating role in the peripartum animal.
S L Lightman; R J Windle; S A Wood; Y M Kershaw; N Shanks; C D Ingram
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Progress in brain research     Volume:  133     ISSN:  0079-6123     ISO Abbreviation:  Prog. Brain Res.     Publication Date:  2001  
Date Detail:
Created Date:  2001-10-08     Completed Date:  2001-11-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376441     Medline TA:  Prog Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  111-29     Citation Subset:  IM    
University Research Centre for Neuroendocrinology, Dorothy Crowfoot Hodgkin Laboratories, University of Bristol, Bristol Royal Infirmary, Bristol BS2 8HW, UK.
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MeSH Terms
Hypothalamo-Hypophyseal System / physiology*
Lactation / physiology*
Paraventricular Hypothalamic Nucleus / physiology
Pituitary-Adrenal System / physiology*
Postpartum Period / physiology*
Pregnancy / physiology*
Pregnancy, Animal / physiology*

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