STUDY OBJECTIVE: To investigate circadian changes in dopaminergic function by means of a neuroendocrine challenge (growth hormone and prolactin responses to an acute oral administration of L-dopa) in patients with idiopathic restless legs syndrome (RLS) and controls. DESIGN: Randomized administration of the L-dopa neuroendocrine challenge. SETTING:Sleep disorders laboratory at a 500-bed academic hospital. PATIENTS OR PARTICIPANTS: Twelve patients diagnosed with idiopathic RLS and 12 age- and sex-matched healthy controls. INTERVENTIONS: Following a comprehensive evaluation that included nocturnal polysomnographic study, all participants underwent the L-dopa neuroendocrine challenge on 2 occasions (11 am and 11 pm). Subjects were previously randomly assigned to the time of first challenge (11 am or 11 pm). On each occasion, subjects took 200 mg of L-dopa (plus 50 mg carbidopa) by mouth. Blood was drawn 20 minutes and 5 minutes before administration of the drug, as well as 15, 30, 45, 60, 75, 90, 102, and 120 minutes after administration. RESULTS:Prechallenge levels of plasma values of growth hormone or prolactin did not differ in the 2 subject groups. Following only the nighttime administration of L-dopa, RLS patients manifested a more pronounced inhibition of prolactin release and an increase in growth hormone secretion. Prolactin plasma levels were significantly correlated to the periodic limb movement index on the polysomnogram. CONCLUSIONS: These findings may reflect enhanced circadian variations in dopaminergic function and support an increased sensitivity at night of dopamine receptors in patients with RLS.
RCT Entities:
STUDY OBJECTIVE: To investigate circadian changes in dopaminergic function by means of a neuroendocrine challenge (growth hormone and prolactin responses to an acute oral administration of L-dopa) in patients with idiopathic restless legs syndrome (RLS) and controls. DESIGN: Randomized administration of the L-dopa neuroendocrine challenge. SETTING:Sleep disorders laboratory at a 500-bed academic hospital. PATIENTS OR PARTICIPANTS: Twelve patients diagnosed with idiopathic RLS and 12 age- and sex-matched healthy controls. INTERVENTIONS: Following a comprehensive evaluation that included nocturnal polysomnographic study, all participants underwent the L-dopa neuroendocrine challenge on 2 occasions (11 am and 11 pm). Subjects were previously randomly assigned to the time of first challenge (11 am or 11 pm). On each occasion, subjects took 200 mg of L-dopa (plus 50 mg carbidopa) by mouth. Blood was drawn 20 minutes and 5 minutes before administration of the drug, as well as 15, 30, 45, 60, 75, 90, 102, and 120 minutes after administration. RESULTS: Prechallenge levels of plasma values of growth hormone or prolactin did not differ in the 2 subject groups. Following only the nighttime administration of L-dopa, RLS patients manifested a more pronounced inhibition of prolactin release and an increase in growth hormone secretion. Prolactin plasma levels were significantly correlated to the periodic limb movement index on the polysomnogram. CONCLUSIONS: These findings may reflect enhanced circadian variations in dopaminergic function and support an increased sensitivity at night of dopamine receptors in patients with RLS.
Authors: Christopher J Earley; Hiroto Kuwabara; Dean F Wong; Charlene Gamaldo; Rachel Salas; James Brasic; Hayden T Ravert; Robert F Dannals; Richard P Allen Journal: Sleep Date: 2011-03-01 Impact factor: 5.849