Melatonin attenuates glucocorticoid effect induced by medroxyprogesterone acetate in rats

Melatonin modulation of the chronic dexamethasone-induced adrenal insufficiency

PURPOSE

Chronic exposure to synthetic glucocorticoids/GCs, widely in use to treat many diseases, may compromise the hypothalamic-pituitary-adrenal/HPA axis leading to a condition of adrenal insufficiency/AI. This study demonstrates the efficacy of the melatonin/MEL in amelioration of chronic dexamethasone (DEX)-induced AI.

METHODS

Mice (Parkes Strain/Male/8 weeks old/30-33 g) were maintained in four groups (10 mice/group) for 30 days: Group 1/Control received intraperitoneal (i.p) vehicle (alcoholic 0.9% normal saline); Group II/DEX (400 µg/kg BW/day/i.p), Group III/(DEX + MEL 750 µg/kg BW/day/subcutaneous), and Group IV received only MEL. Adrenal, pituitary, and blood samples were collected from six mice/groups. Four mice/groups were subjected to the Lipopolysaccharide (LPS) challenge. Adrenal histology, ACTH immunohistochemistry, and plasma ACTH and corticosterone/CORT levels were measured.

RESULTS

DEX exposure suppressed the pituitary ACTH expression significantly from control as revealed by morphometry and circulating hormones (Density, p < 0.01; size, immunointensity, plasma ACTH, and CORT; p < 0.001). Increased adrenal histopathology indicated probable AI. MEL co-supplementation significantly increased the corticotropes' density (p < 0.05), size (p < 0.001), immunointensity (<0.01), and plasma level of ACTH (p < 0.01) compared to the DEX group. The adreno-cortical width, zona fasciculata cell density and size, and the plasma CORT level (p < 0.001) were also significantly increased. The enhanced CORT response of the HPA axis in the DEX + MEL group compared to the DEX group on the LPS challenge provides support for the MEL restoration of the HPA axis functioning.

CONCLUSION

Further research on the MEL modulation of the HPA axis may support its role in preventing AI.

Meta-analysis and machine learning reveal the antiobesity effects of melatonin on obese rodents

Melatonin appears to be a promising supplement for obesity treatment. The antiobesity effects of melatonin on obese rodents are influenced by various factors, including the species, sex, the dosage of melatonin, treatment duration, administration via, daily treatment time, and initial body weight (IBW). Therefore, we conducted a meta-analysis and machine learning study to evaluate the antiobesity effect of melatonin on obese mice or rats from 31 publications. The results showed that melatonin significantly reduced body weight, serum glucose (GLU), triglycerides (TGs), low-density lipoprotein (LDL), and cholesterol (TC) levels in obese mice or rats but increased high-density lipoprotein (HDL) levels. Melatonin showed a slight positive effect on clock-related genes, although the number of studies was limited. Meta-regression analysis and machine learning indicated that the dosage of melatonin was the primary factor influencing body weight, with higher melatonin dosages leading to a stronger weight reduction effect. Together, male obese C57BL/6 mice and Sprague-Dawley rats with an IBW of 100-200 g showed better body weight reduction when supplemented with a dose of 10-30 mg/kg melatonin administered at night via injection for 5-8 weeks.

Molecular Assessment of Proadipogenic Effects for Common-Use Contraceptives and Their Mixtures

Hormonal contraceptives are widely prescribed due to their effectiveness and convenience and have become an integral part of family planning strategies worldwide. In the United States, approximately 65% of reproductive-aged women are estimated to be using contraceptive options, with approximately 33% using one or a combination of hormonal contraceptives. While these methods have undeniably contributed to improved reproductive health, recent studies have raised concerns regarding their potential effect on metabolic health. Despite widespread anecdotal reports, epidemiological research has been mixed as to whether hormonal contraceptives contribute to metabolic health effects. As such, the goals of this study were to assess the adipogenic activity of common hormonal contraceptive chemicals and their mixtures. Five different models of adipogenesis were used to provide a rigorous assessment of metabolism-disrupting effects. Interestingly, every individual contraceptive (both estrogens and progestins) and each mixture promoted significant adipogenesis (eg, triglyceride accumulation and/or preadipocyte proliferation). These effects appeared to be mediated in part through estrogen receptor signaling, particularly for the contraceptive mixtures, as cotreatment with fulvestrant acted to inhibit contraceptive-mediated proadipogenic effects on triglyceride accumulation. In conclusion, this research provides valuable insights into the complex interactions between hormonal contraceptives and adipocyte development. The results suggest that both progestins and estrogens within these contraceptives can influence adipogenesis, and the specific effects may vary based on the receptor disruption profiles. Further research is warranted to establish translation of these findings to in vivo models and to further assess causal mechanisms underlying these effects.