Melatonin and Pituitary‐Gonadal Function in Disorders of Eating Behavior

Abstract

In order to study the possible relationships between melatonin secretion and pituitary-gonadal function, the circadian rhythm of plasma melatonin, the basal levels of estradiol-17beta and testosterone and the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) response to luteinizing hormone-releasing hormone (LH-RH) stimulation were evaluated in normally cycling healthy women and in two groups of women with menstrual dysfunctions related to eating disorders (19 patients with anorexia nervosa and 16 with primary obesity). The circadian rhythm of plasma melatonin reached statistical significance in anorectic patients but not in obese patients. The mean 24 h melatonin level was significantly higher in anorectic than in obese patients and in control subjects. However, both groups of patients shared some abnormalities of melatonin circadian pattern, such as increased ratio between day and night melatonin levels, abnormal secretory peaks during the light hours and great interindividual variability for timing, amplitude, and duration of melatonin nocturnal peak. A selective impairment of LH secretion was observed in both anorectic and obese patients. By considering together the two groups of patients and controls, a linear inverse correlation between the circadian mesor of plasma melatonin and the basal and LH-RH stimulated LH levels was found. The persistence of a certain melatonin secretion during the light hours in both anorectic and obese patients could play an inhibitory role on the pituitary gonadal function in these subjects.

The effect of food deprivation on brain and gastrointestinal tissue levels of tryptophan, serotonin, 5‐hydroxyindoleacetic acid, and melatonin

“…In accordance with the above studies, 50% reduction in food intake lasting for 3 weeks, decreased the mid scotophase peak levels of pineal melatonin by 12%. Surprisingly, serum melatonin concentrations were increased by some 34% [Chik et al, 19851. Underfeeding has also been shown to increase serum melatonin levels in human volunteers [Breitins et al, 19851. In addition, higher melatonin levels were also reported in blood of human patients suffering from anorexia nervosa [Ferrari et al, 1989;Tortosa et al, 19891; these patients also exhibited a highly significant reduction in food intake.…”

Role of melatonin in health and disease

“…After exposure to darkness for 2 hours during daytime, he showed an abnormal increase in MEL, while after exposure to a bright light (3500 lux) for 2 hours at night, a marked initial rise was followed by a slight fall, but complete inhibition was not observed, such as that seen in three normal men similarly exposed to 3500 lux at midnight @) (from Puig-Domingo et al, 1992, with permission). functional hypothalamic hypogonadism (Brzezinski et al., 1988) or anorexia nervosa (Brambilla et al, 1988; Tortosa ef al., 1989;Ferrari et al, 1989;Arendt et al, 1992), all with low gonadotrophins, and in men suffering from primary hypogonadism with elevated gonadotrophins (0. Rajmil et al, unpublished), or infertility with oligozoospermia or azoospermia (Karasek er al., 1990).…”

New Issues About Melatonin and its Effects on the Digestive System

“…Remarkable findings also relate melatonin with apetite regulation and with the synchronization of feeding and digestion processes. Individuals suffering from anorexia nervosa and underfed volunteers, registered a significant rise in the plasmatic levels of the hormone [141,142], which was also observed after food intake [143]. The increase induced by feeding may entrain the sequence of the digestive processes essential for the proper utilization of food, whereas the elevation of melatonin caused by starvation may initiate an Some authors correlate the circadian production of the hormone with the expression of gastrointestinal receptors.…”