Abstract. Plasma melatonin circadian profiles were investigated in a group of 4 patients with anorexia nervosa and 4 healthy regularly cycling women. There were no differences in the mean age of both groups, whereas the anorexia nervosa patients had lower mean body weight (37.8 ± 2.0 vs 57.0 ± 4.9 kg) and body mass index (13.9 ± 1.1 vs 20.8 ± 2.0). Samples were collected every 2 h and plasma melatonin was measured by using a RIA with an iodinated tracer. Anorexia nervosa patients exhibited higher diurnal (60.7 ± 1.8 vs 25.4 ± 1.72 pmol/l, P< 0.02) and nocturnal (419.2 ± 37.4 vs 108.0 ± 33.6 pmol/l), P< 0.001) mean plasma melatonin concentrations. There were no differences in the time peak for nocturnal melatonin secretion in both groups, detected at 02.00 h. In anorexia nervosa, the melatonin circadian profile paralleled that observed in the control group, indicating that the increased melatonin values for anorexia nervosa were probably due to an enhanced secretory pineal function rather than an impaired melatonin metabolism. These results suggest a participation of the pineal gland in the pathophysiology of anorexia nervosa.

Ghrelin is higher in old men in comparison to women and decreases over time with a steeper decline in subjects with MS; moreover, in these subjects ghrelin/IGF-I correlation is lost.

No abstract

Immunoreactive somatostatin (IRS) has been previously demonstrated in the pineal gland of different rodent species, and we observed a 24-hr rhythm in rats. Recent data suggest that the peptide may represent a neurotransmitter in the so-called peptidergic nerves of the central, pinealopetal innervation of the epiphysis, which may modulate the activity and secretion of the gland. We investigated whether 24-hr changes of pineal IRS content occurred in Syrian hamsters, gerbils, and mice. Adult males, kept in a 14:10 LD photoperiod, were decapitated at 4-hr intervals throughout a 24-hr period. Pineals and median eminences were analyzed for IRS by radioimmunoassay. No significant changes in the median eminence content of IRS with time was observed. As previously described in rats, a statistically significant rhythm of IRS was observed in the pineal of hamsters and mice, with a peak at 2000 hr (mice 51.7 +/- 5 pg/pineal; hamsters 26.3 +/- 4.6) and a nadir at 2400 hr (mice 30.8 +/- 1.4) or 0400 hr (hamsters 8.6 +/- 1). However, in the gerbil pineal IRS content remained unchanged throughout the period of study. Since the three species examined have very different melatonin cycles, it is suggested that the melatonin and IRS rhythms are unrelated and independently regulated events within the pineal gland.

No abstract