Assessment of the relationship between circadian variations of salivary melatonin levels and type I collagen metabolism in postmenopausal obese women.

BACKGROUND: Few experimental and clinical studies show that melatonin (MEL) can play a significant part to modulate circadian bone metabolism. On this basis it was suggested that MEL secretion which altered during 24-h in obese women could be of importance to regulate bony mass defect after menopause. OBJECTIVE: The aim of the study was to prove if there were any connection between changes in 24-h profile of serum MEL levels and circadian metabolism of type I collagen in postmenopausal women with visceral obesity. METHODS: The relationship of 24-h profile of salivary MEL and circadian metabolism of type I collagen (as assessed by measuring saliva concentrations of carboxyterminal propeptide of type I procollagen--PICP and cross-linked carboxyterminal telopeptide of type I collagen--ICTP) was investigated in 26 women with visceral obesity (33.5 < BMI < 42.1 kg/m(2)) and 18 healthy volunteers with correct body mass (21 < BMI < 24.5 kg/m(2); 0.73 < WHR < 0.76). The specimens were collected at subjects' home at 3 h intervals during a 24 h span. The age range of all subjects was 52-60 years. RESULTS: In all the obese women studied a tendency to suppress circadian levels of tested biochemical markers of bone metabolism was observed (especially regarding ICTP); those alterations were accompanied by substantial increment in MEL concentrations during the day. Significant and negative correlation was found between values of acrophase MEL and PICP rhythms and both amplitude and acrophase of MEL and ICTP rhythms. CONCLUSION: Our results confirm hypothesis that alterations in MEL concentrations might have a protective effect against postmenopausal loss of bone mass.

Assessment of the relationship between dynamic pattern of nighttime levels of melatonin and chosen biochemical markers of bone metabolism in a rat model of postmenopausal osteoporosis.

BACKGROUND: Lately, there have been suggestions that bone mass changes occurring in postmenopausal women may remain related to melatonin. OBJECTIVE: To assess the relationship between the dynamic pattern of nighttime levels of melatonin and chosen biochemical markers of bone metabolism in ovariectomized rats--a model of postmenopausal osteoporosis. METHODS: Mature Wistar female rats were either ovariectomozed or underwent a sham operation. Following this they were killed at 02:00AM at weekly intervals for 8 weeks after surgery. Serum levels of MEL at death related to the chosen biochemical markers of bone formation (alkaline phosphatase--ALP; carboxyterminal propeptide of type I procollagen--PICP, both in serum) and resorption (cross-linked carboxyterminal telopeptide of type I collagen--ICTP in serum; hydroxyproline--HYP and total calcium--Ca, both excreted in urine). RESULTS: In all ovariectomized rats changes of examined indices of bone tissue metabolism were found to be dynamic and statistically significant relative to the control group; however the changes were more pronounced regarding resorption markers. Following ovariectomy, the increase in ALP and PICP values was found to begin at the 4th and the 1st week, while that in ICTP, HYP and Ca at the 2nd, the 1st and the 1st week, respectively. The ALP and PICP values remained at a similar level until the end of observation, whereas ICTP, HYP and Ca gradually decreased. MEL levels were decreased during the 2nd week following surgery and slightly increased 2 weeks later. The serum MEL levels in the ovariectomized group were significantly and negatively correlated with serum ICTP and both urinary HYP and Ca levels. CONCLUSION: Our findings in rats seem to corroborate the concept of secondary changes in MEL levels co-participating in the development of bone mass changes characteristic for postmenopausal osteoporosis.

Quantitative ultrasound of the heel and serum and urinary cortisol values in assessment of long-term corticotherapy side effects in female bronchial asthma patients.

Female asthma patients (26) with and without corticotherapy were studied. The control group included 19 healthy women. Skeletal status was assessed by ultrasound measurement of the heel (Achilles, Lunar, Madison, WI, USA) and serum and urinary corisol expressed adrenal function. Ultrasound and hormonal values were significantly lower in patients treated with glucocorticosteroids (GC) than in controls. In patients without GC, cortisol parameters were normal and ultrasound measurements were moderately diminished. 57% of women with and 33% of women without GC-therapy had an ultrasound T-score less than -2.5. Decrease of ultrasound values estimated by linear regression in relationship to time of asthma duration was highest in women with GC therapy. Several significant coefficients of correlation between ultrasound and adrenal function parameters were noted only in patients treated with GC. These data suggest that bone and endocrinological side effects due to steroid therapy in asthma patients show similar trends. Results obtained in present study require further longitudinal investigations.