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Changes in hypothalamic calmodulin concentration induced by perinatal hormone manipulation in the rat
M A Rodríguez-Medina1, M Vergara, M E Chavarria
1División de Investigación Biomédica, Unidad de Investigación Médica en Biología de la Reproducción, Hospital de Gineco-Obstetrica Luis Castelazo Ayala, IMSS México DF, México.
Pharmacology, Biochemistry, and Behavior
|November 5, 1998
Summary
Hormonal influences on calmodulin (CaM) in the rat hypothalamus reveal age- and sex-dependent changes. Newborn hormonal treatments permanently alter CaM levels, suggesting a role in reproductive function.
Area of Science:
- Neuroendocrinology
- Molecular Biology
- Developmental Neuroscience
Background:
- Calmodulin (CaM) is a crucial calcium-binding protein involved in numerous cellular processes.
- Hypothalamic CaM levels exhibit dynamic changes during development and in response to hormonal stimuli.
- Understanding CaM's role in the hypothalamus is vital for comprehending reproductive functions.
Purpose of the Study:
- To investigate the developmental changes in rat hypothalamic calmodulin (CaM) concentration.
- To examine the effects of neonatal testosterone propionate (TP) and tamoxifen administration on CaM levels.
- To determine the influence of sex and hormonal manipulation on CaM synthesis and concentration in the hypothalamus.
Main Methods:
- Radioimmunoassay (RIA) was employed to quantify CaM concentration in rat hypothalamus at various postnatal ages (2h, 6h, 12h, 24h, 90 days).
- Animals were treated neonatally with vehicle (controls), testosterone propionate (TP) in females, or tamoxifen in males.
- CaM levels were assessed as total content per hypothalamus and concentration per milligram of wet weight (ww) or protein.
Main Results:
- Hypothalamic CaM concentration significantly increased with age in both male and female rats, being substantially higher in adults than newborns.
- Adult females exhibited higher CaM concentrations than adult males, a reversal of the trend observed in newborns.
- Neonatal TP treatment in females and tamoxifen treatment in males led to a significant decrease in CaM levels in both neonates and adults, with treated females showing levels similar to control males.
Conclusions:
- Neonatal hormonal treatments exert a lasting effect on hypothalamic CaM concentration in rats.
- The adult female hypothalamus preferentially synthesizes CaM, indicating its significant role in female reproductive function.
- CaM levels in the hypothalamus are dynamically regulated by age, sex, and hormonal milieu, impacting neuroendocrine processes.