par Van Cauter, Eve ;L'Hermite, Marc ;Copinschi, Georges
Référence American journal of physiology: endocrinology and metabolism, 4, 5, page (355-363)
Publication Publié, 1981
Article révisé par les pairs
Résumé : Eighteen 24-h profiles of plasma prolactin (PRL) were obtained at 15- or 30-min intervals in 10 healthy male volunteers, investigated in summer, autumn, and winter. The sleep-associated elevation of PRL concentration was observed in all profiles. Sixteen of 18 profiles were bimodal with a daytime, as well as a nighttime, elevation of plasma PRL. On the average, the magnitude of the daytime acrophase corresponded to about 50% of the magnitude of the nocturnal acrophase. The absolute increment of PRL from morning nadir to nocturnal acrophase appeared to be independent of the basal PRL level. Approximately 40% of the variability of plasma PRL values corresponded to episodic fluctuations. A total of 210 PRL spikes were found in the 15 24-h profiles obtained at 15-min intervals. Each PRL spike was evaluated in terms of its significance, of the duration of its ascending and declining portions, of its magnitude defined as the relative elevation over the preceding trough, and of the apparent half-life. Sixty-five percent of the spikes lasted less than 75 min. The apparent half-lives were longer (median, 42 min) than other estimations of the half-life of PRL (around 20 min) and were positively correlated with the level before spiking, suggesting that PRL is secreted in pulses of variable amounts superimposed to a continuous basal secretion. The magnitude of the spikes corresponded to an average relative increment of 116%. No seasonal modulation could be demonstrated. The 24h pattern of PRL secretion, although occurring around basal levels varying considerably from one individual to another, was otherwise very reproducible. The 24-h mean plasma PRL level and the number of secretory spikes appeared to be characteristic of a given individual.