The relationship between melatonin secretion and serum cholesterol in patients with multiple sclerosis.

We have reported recently that nocturnal melatonin levels are reduced in a subgroup of patients with multiple sclerosis (MS). We have also noted in these patients a high incidence of hypercholesterolemia and propose that this may be linked to dysfunction of the pineal gland since pinealectomy in rats was reported to be associated with elevation of blood cholesterol levels. To test this hypothesis, we studied the relationship between nocturnal plasma melatonin levels and serum cholesterol levels in a cohort of 24 MS patients (4 men; 20 women; mean age: 40.2 years SD = 9.5) who were admitted to an inpatient neurologic clinic for acute exacerbation of symptoms. For the purpose of comparison we also evaluated in these patients the association between melatonin levels and serum triglyceride (TG) levels. As predicted, we found a significantly higher serum cholesterol level in 10 patients who had low nocturnal plasma melatonin levels (mean: 17.1 pg/ml +/- 5.9) compared to 14 patients in whom melatonin levels were in the normal range (mean: 42.9 pg/ml +/- 10.6) (mean cholesterol = 241.5 mg/dl +/- 50.8 vs. 183.7 mg/dl +/- 27.2; p < .001). In contrast, serum TG levels did not differ significantly between the groups. As serum cholesterol levels were statistically unrelated to TG levels, these findings suggest a specific association between pineal melatonin and cholesterol metabolism. If confirmed in future research, these findings suggest that the pineal gland may exert a cholesterol reducing effect and that melatonin could be used therapeutically in the treatment of hypercholesterolemia.