Corticosteroid response to stress depends upon increased tryptophan availability.

Area of Science:

• Neuroscience
• Endocrinology
• Biochemistry

Background:

• Restraint stress increases brain tryptophan and serotonin (5HT) turnover.
• Valine administration previously showed it could prevent these stress-induced changes.
• The effect of valine on the corticosteroid stress response was not fully understood.

Purpose of the Study:

• To investigate the role of tryptophan and other amino acids in the corticosteroid response to stress.
• To determine if the corticosteroid response to stress is mediated by serotonergic activity.
• To explore potential amino acid-based interventions for stress-related disorders.

Main Methods:

• Rats were subjected to restraint stress.
• Administration of valine, tryptophan, and tyrosine, alone or in combination.
• Measurement of brain tryptophan and 5HT turnover.
• Assessment of corticosteroid levels.

Main Results:

• Tryptophan administration reversed valine's attenuation of the corticosteroid response to stress.
• Tyrosine did not reverse this attenuation and reduced the corticosteroid response when given alone.
• These findings suggest a link between serotonergic activity and the corticosteroid stress response.

Conclusions:

• The corticosteroid response to restraint stress involves increased serotonergic activity dependent on tryptophan supply.
• Amino acids like valine and tyrosine can antagonize this response by competing for brain access.
• These findings have implications for understanding and managing stress-associated human disorders.