Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Exposure to estradiol impairs luteinizing hormone function during aging.

T J Collins1, T A Parkening

  • 1Department of Anatomy and Neurosciences, University of Texas Medical Branch, Galveston 77550.

Mechanisms of Ageing and Development
|May 1, 1991
PubMed
Summary
This summary is machine-generated.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Designing Endocrine Disruption Out of the Next Generation of Chemicals.

Green chemistry : an international journal and green chemistry resource : GC·2014
Same author

Global revascularization.

Ochsner journal·2011
Same author

Percutaneous coronary angioscopy Current status and future directions.

Trends in cardiovascular medicine·2011
Same author

Infrapopliteal drug-eluting stents for chronic limb ischemia.

Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions·2007
Same author

N type Ca2+ channels and RIM scaffold protein covary at the presynaptic transmitter release face but are components of independent protein complexes.

Neuroscience·2006
Same author

Application of TAML catalysts to remove colour from pulp and paper mill effluents.

Water science and technology : a journal of the International Association on Water Pollution Research·2004
Same journal

Human sex-specific hormone effects on cerebrovascular health in males and females.

Mechanisms of ageing and development·2026
Same journal

HTZ-1/H2A.Z expression sustains transcriptional programs that regulate Caenorhabditis elegans lifespan.

Mechanisms of ageing and development·2026
Same journal

PCSK9 promotes aging-related cardiac calcification by inducing osteogenic differentiation of cardiac fibroblasts.

Mechanisms of ageing and development·2026
Same journal

Distinct post-infectious TLR2 immune remodeling in COVID-19-recovered centenarians.

Mechanisms of ageing and development·2026
Same journal

Senescence-associated tertiary lymphoid structures in Sjögren's disease model nishiura mice.

Mechanisms of ageing and development·2026
Same journal

Aging-driven reprogramming of CD34⁺ hematopoietic stem cells in leukemogenesis: Mechanisms and therapeutic implications.

Mechanisms of ageing and development·2026
See all related articles

This study investigates how aging and long-term exposure to the hormone estradiol affect the ability of the pituitary gland to release luteinizing hormone, which is necessary for ovulation in mammals. The researchers found that while younger mice show a normal two-part hormone release pattern, older mice exhibit a diminished response. This impairment is linked to a failure in protein-dependent processes within the pituitary gland. Importantly, mice deprived of estradiol from a young age maintained a youthful hormone response, suggesting that chronic exposure to this hormone contributes to the age-related decline in reproductive function.

Area of Science:

  • Endocrinology and reproductive physiology research within estradiol signaling pathways
  • Gerontology and aging biology studies

Background:

Reproductive senescence in mammals frequently stems from dysregulation within the hypothalamic-pituitary axis. That uncertainty drove researchers to investigate how aging modifies the preovulatory release of luteinizing hormone. Prior research has shown that ovulatory cycles cease as animals transition into advanced age. No prior work had resolved whether the anterior pituitary gland itself loses the capacity to secrete hormones effectively over time. This gap motivated an examination of how specific hormonal signals influence pituitary performance during the aging process. Scientists have long suspected that hormonal environments play a role in tissue decline. However, the exact contribution of chronic exposure to specific steroids remained unclear. This study addresses these questions by comparing pituitary responses across various age groups and hormonal conditions.

Purpose Of The Study:

The aim of this study was to evaluate the anterior pituitary component of the hypothalamic-pituitary axis during the aging process. Researchers sought to determine how age-related changes influence the ability of pituitary tissue to release luteinizing hormone. The investigation specifically focused on the dual discharge profile observed during pulsatile stimulation with luteinizing hormone-releasing hormone. A primary motivation was to clarify whether the pituitary gland itself loses functional capacity as mammals transition into reproductive senescence. The team also aimed to test the hypothesis that chronic exposure to estradiol contributes to these observed declines in hormone function. By comparing mice with different hormonal histories, the study intended to isolate the impact of long-term steroid exposure. This work addresses the uncertainty regarding whether pituitary dysfunction is an inherent result of aging or a consequence of hormonal signaling. The researchers designed the study to provide a comprehensive assessment of secretory mechanisms in the aging pituitary.

Keywords:
reproductive senescencepituitary glandhormone secretionovulatory cyclicity

Frequently Asked Questions

The researchers propose that the pituitary gland fails to execute protein-dependent synthetic processes, such as hormone packaging or new production. This mechanism prevents the second phase of the dual discharge pattern in older mice, unlike the robust response observed in younger, mature subjects.

The study utilizes perifused anterior pituitary tissue to measure hormone release. This technique allows for the observation of dynamic secretory responses following sustained, pulsatile stimulation with luteinizing hormone-releasing hormone, providing a controlled environment to assess tissue-specific functional capacity across different age cohorts.

The protein-dependent phase of the response is necessary to observe the full dual discharge profile. While the initial hour of secretion remains unaffected by cycloheximide, the subsequent phase requires active protein synthesis, which becomes significantly reduced in older, irregularly cycling, or anestrus mice.

Related Experiment Videos

Main Methods:

The review approach involved analyzing the secretory capacity of anterior pituitary tissue harvested from mice of varying ages. Researchers utilized a perifusion system to maintain tissue viability while delivering controlled, pulsatile stimulation with luteinizing hormone-releasing hormone. This design allowed for the precise monitoring of hormone discharge profiles over time. The team compared mature, declining, and anestrus mice to establish a baseline for age-related changes. To isolate the effects of specific steroids, the investigators employed ovariectomized subjects with and without hormone replacement. Cycloheximide was introduced to distinguish between immediate secretory responses and those requiring active protein synthesis. This methodology provided a clear distinction between early and late phases of hormone release. The experimental setup ensured that the observed differences were attributable to pituitary-specific mechanisms rather than systemic hypothalamic inputs.

Main Results:

Key findings from the literature reveal that the dual discharge profile of hormone release is significantly altered by age. The initial hour of the secretory response remains consistent across all age groups, showing no significant variation in mature versus older mice. However, the subsequent protein synthesis-dependent phase is notably reduced in mice aged 16 to 18 months and 22 to 24 months. Ovariectomized mice deprived of estradiol since puberty demonstrate a secretory capacity comparable to that of mature proestrous groups. In contrast, aged mice subjected to long-term estradiol exposure fail to produce the characteristic dual response pattern. These results indicate that the impairment occurs specifically during the phase involving hormone packaging or new production. The data suggest that the pituitary gland retains its early-phase function while losing its late-phase synthetic capabilities. These observations highlight a clear divergence in secretory performance based on both chronological age and cumulative hormonal exposure.

Conclusions:

The authors propose that the age-related decline in luteinizing hormone release involves a failure in protein-dependent synthetic pathways. Their findings suggest that the pituitary gland loses its ability to package or produce new hormone stores as animals age. The researchers conclude that estradiol acts as a significant factor in driving these functional changes within the pituitary. This process appears to initiate well before the onset of middle age. Mice deprived of estradiol from puberty maintain a youthful response profile, indicating that long-term hormone exposure is detrimental. The study implies that the dual discharge pattern of hormone release is highly sensitive to the cumulative hormonal history of the subject. These results provide a framework for understanding how chronic steroid exposure contributes to reproductive aging. The authors emphasize that the pituitary component of the axis is a primary site for these age-associated impairments.

Estradiol serves as a critical variable in this investigation. By comparing ovariectomized mice deprived of this hormone since puberty against those receiving long-term replacement, the authors demonstrate that chronic exposure to this specific steroid is associated with the loss of the dual discharge pattern.

The researchers measured the dual discharge profile of luteinizing hormone release. They observed that mature mice exhibit a robust two-part response, whereas aged mice show a diminished second phase, specifically when those subjects have been exposed to long-term hormone replacement therapy.

The authors propose that estradiol acts as a major factor in altering pituitary function well before middle age. They suggest that the cumulative exposure to this hormone throughout the lifespan is a primary driver of the observed reproductive decline in aging mammals.