Platelet hyperaggregability and increased alpha-adrenoceptor density in anorexia nervosa

Area of Science:

• Neuroendocrinology
• Hematology
• Psychiatry

Background:

• Anorexia nervosa is associated with significant physiological alterations.
• Autonomic nervous system dysfunction is implicated in the pathophysiology of anorexia nervosa.
• Platelet function and adrenoceptor expression may be affected by malnutrition and starvation.

Purpose of the Study:

• To investigate plasma norepinephrine concentrations in patients with anorexia nervosa.
• To examine platelet alpha-adrenoceptor densities and subtypes in these patients.
• To assess the impact of altered adrenoceptor levels on epinephrine-induced platelet aggregation.

Main Methods:

• Measurement of plasma norepinephrine levels.
• Quantification of platelet alpha-adrenoceptor densities using radioligand binding assays.
• Assessment of platelet aggregation response to epinephrine.
• Comparison between patients with anorexia nervosa and age/sex-matched healthy controls.

Main Results:

• Significantly lower plasma norepinephrine concentrations were observed in anorexia nervosa patients compared to controls.
• Platelet total alpha-adrenoceptor densities were significantly higher in patients.
• The increase in alpha-adrenoceptors was primarily attributed to the alpha 2-subtype.
• Platelet aggregation response to epinephrine was significantly enhanced in anorexia nervosa patients.

Conclusions:

• Starvation in anorexia nervosa leads to a decrease in plasma norepinephrine.
• This decrease is associated with an up-regulation of platelet alpha-2 adrenoceptors.
• The enhanced alpha-adrenoceptor density explains the exaggerated epinephrine-induced platelet aggregation in these patients.