Acceleration of re-entrainment during a 6-h acute jet lag simulation by 5-hydroxy-l-tryptophan in pygmy field mice

Abstract

L-5-Hydroxytryptophan (5-HTP), the precursor of serotonin, is known to cause temporally differentiated phase shifts. However, its effects on acceleration of re-entrainment have not been demonstrated before. We report significant acceleration of re-entrainment to a 6-h advanced light dark schedule by 50 mg/kg 5-HTP (∼8 transients reduced to ∼3 transients) injected at ∼ZT 6 in the nocturnal Indian pygmy field mouse, Mus terricolor. The mechanistic explanation is currently unknown, but this probably occurs through serotonergic phase and period modifications. 5-HTP is thus potentially useful as a chronobiotic in circadian rhythm disorders.

Keywords:

• jet lag
• re-entrainment
• acceleration
• 5-HTP
• pygmy mice

Acknowledgements

Financial aid to MS by Banaras Hindu University vide grant No. F(A)1-14(G)/3449, research grant through UGC Major Research Project No. F.39-572/210(SR) to MS, help with animal handling by Mr Punit Kumar and CSIR-UGC Senior Research Fellowship to PB are thankfully acknowledged.