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Age-related decrease of growth hormone and prolactin gene expression in the mouse pituitary
M D Crew1, S R Spindler, R L Walford
1Department of Biochemistry, University of California, Riverside 92521.
Abstract:
The effects of aging on pituitary GH, PRL, and alpha-tubulin messenger RNA (mRNA) levels were measured in 3-, 12-, and 27-month-old male C57BL/6J mice by dot-blot hybridization. The amount of GH and PRL mRNA in the pituitary deceased dramatically with age. However, total poly(A+) RNA (mRNA), as measured by hybridization with radioactively labeled oligo-(dT), was not altered during aging. In addition, there were no age-related changes in the level of alpha-tubulin mRNA. Thus, the effects of aging on GH and PRL mRNA levels are specific; the levels of the majority of cellular mRNAs are not altered with age. GH and mRNA levels decreased 35% between 3 and 12 months (P less than 0.05) and a total of 75% after 27 months (P less than 0.01). PRL mRNA levels decreased 65% between 12 and 27 months (P less than 0.01), although there was no significant decrease before 12 months. Whereas T3 is the most potent regulator of GH gene expression, we did not detect any significant age-related change in serum T3 levels. These results suggest that factors other than T3 play a role in the age-related decline in GH and PRL gene expression.
Insights
Aging significantly reduces pituitary growth hormone (GH) and prolactin (PRL) mRNA levels in mice. This decline is specific, as other messenger RNA (mRNA) levels remain unchanged, suggesting age-related factors beyond T3 influence gene expression.
Area of Science:
- Endocrinology
- Molecular Biology
- Aging Research
Background:
- Pituitary hormones like growth hormone (GH) and prolactin (PRL) play crucial roles in physiological functions.
- Age-related changes in gene expression can impact hormone production and secretion.
- Understanding molecular mechanisms underlying aging is vital for healthspan research.
Purpose of the Study:
- To investigate the impact of aging on pituitary growth hormone (GH) and prolactin (PRL) messenger RNA (mRNA) levels in male mice.
- To determine if age-related changes in GH and PRL mRNA are specific or widespread across cellular mRNAs.
- To explore potential correlations between age-related hormone mRNA decline and serum T3 levels.
Main Methods:
- Utilized dot-blot hybridization to quantify GH, PRL, and alpha-tubulin mRNA levels in pituitaries of 3-, 12-, and 27-month-old male C57BL/6J mice.
- Assessed total poly(A+) RNA (mRNA) levels using hybridization with radioactively labeled oligo-(dT).
- Measured serum T3 levels to evaluate its potential role in age-related gene expression changes.
Main Results:
- A dramatic age-dependent decrease in pituitary GH and PRL mRNA levels was observed.
- GH mRNA levels dropped by 35% between 3 and 12 months, and 75% by 27 months.
- PRL mRNA levels decreased by 65% between 12 and 27 months, with no significant change before 12 months.
- Total mRNA and alpha-tubulin mRNA levels showed no significant age-related alterations.
- No significant age-related changes were detected in serum T3 levels.
Conclusions:
- Aging specifically reduces GH and PRL mRNA levels in the pituitary gland of male mice.
- The observed decline in GH and PRL mRNA is not indicative of a general age-related decrease in cellular mRNA.
- The results suggest that factors other than T3 are involved in the age-related decline of GH and PRL gene expression.