Estimation of frequently sampled nocturnal melatonin production in humans by deconvolution analysis: Evidence for episodic or ultradian secretion

In order to investigate nocturnal melatonin production and clearance rates: we applied deconvolution analysis to plasma melatonin concentration time s eries obtained every 20 min for 12 hr from 20:00 h to 08:00 h in two groups of healthy subjects at rest (group 1, 12 male subjects. 22-26 yr, group 2, ten female subjects, 31-42 yr). The estimated melatonin production rate Fr om group 1 (0.55 +/- 0.21 mu g/kg/night) was significantly higher than that of group 2 (0.26 +/- 0.19 mu g/kg/night), as well as the mass of melatonin released per burst (275 +/- 110 vs. 145 +/- 130 pg/mL for groups 1 and 2, respectively). the amplitude of secretory bursts (7.8 +/- 3.2 vs. 4.7 +/- 3 .5 pg/mL/min), and the pulsatile melatonin production rate (2.76 +/- 1.14 v s. 1.27 +/- 0.97 ng/mL/night). These differences could reflect alterations related to age and/or gender, No differences were observed between the two groups in the secretory burst half-duration and frequency and the interburs t interval. Melatonin production rates, as estimated by deconvolution analy sis, are in agreement with other independent estimates, especially the isot opic method, and disclose an ultradian rhythmicity.