Association of serum uric acid levels with bone mineral density and the presence of osteoporosis in Chinese patients with Parkinson's disease: a cross-sectional study

Association between serum insulin-like growth factor 1 and osteoporosis risk in Parkinson's disease: a cross-sectional study

OBJECTIVE

To examine the correlation between serum insulin-like growth factor 1 (IGF-1) and osteoporosis (OP) in Parkinson's disease (PD).

METHODS

We retrospectively analyzed clinical data from 105 PD patients (PD group) and 78 individuals in the health examination group (HC group). We compared general clinical data and serum IGF-1 levels between the two groups. PD patients were further categorized into PD with OP (50 cases) and PD without OP (55 cases) based on dual-energy X-ray absorptiometry (DXA) results for bone density. We compared general clinical data and serum IGF-1 levels between these two subgroups. Pearson correlation coefficient analysis was conducted to assess the relationship between serum IGF-1 levels and bone density at the lumbar spine and left femoral neck. Multifactorial logistic regression analysis was performed to identify risk factors for PD with OP.

RESULTS

Serum IGF-1 levels were significantly lower in the PD group compared to the HC group (P < 0.05). Pearson correlation analysis revealed a positive association between serum IGF-1 levels and both lumbar spine and left femoral neck bone densities (r = 0.653, P < 0.001; r = 0.625, P < 0.001). Multivariate logistic regression analysis identified decreased serum IGF-1 levels, lower uric acid levels, and higher H-Y stage as risk factors for PD with OP (P < 0.05).

CONCLUSION

Reduced levels of serum IGF-1, uric acid, and an increased H-Y stage are closely linked to osteoporosis in PD. Elevating serum levels of IGF-1 and uric acid may potentially offer therapeutic avenues for PD with osteoporosis.

Vitamin D, Calbindin, and calcium signaling: Unraveling the Alzheimer's connection

Calcium is a ubiquitous second messenger that is indispensable in regulating neurotransmission and memory formation. A precise intracellular calcium level is achieved through the concerted action of calcium channels, and calcium exerts its effect by binding to an array of calcium-binding proteins, including calmodulin (CAM), calcium-calmodulin complex-dependent protein kinase-II (CAMK-II), calbindin (CAL), and calcineurin (CAN). Calbindin orchestrates a plethora of signaling events that regulate synaptic transmission and depolarizing signals. Vitamin D, an endogenous fat-soluble metabolite, is synthesized in the skin upon exposure to ultraviolet B radiation. It modulates calcium signaling by increasing the expression of the calcium-sensing receptor (CaSR), stimulating phospholipase C activity, and regulating the expression of calcium channels such as TRPV6. Vitamin D also modulates the activity of calcium-binding proteins, including CAM and calbindin, and increases their expression. Calbindin, a high-affinity calcium-binding protein, is involved in calcium buffering and transport in neurons. It has been shown to inhibit apoptosis and caspase-3 activity stimulated by presenilin 1 and 2 in AD. Whereas CAM, another calcium-binding protein, is implicated in regulating neurotransmitter release and memory formation by phosphorylating CAN, CAMK-II, and other calcium-regulated proteins. CAMK-II and CAN regulate actin-induced spine shape changes, which are further modulated by CAM. Low levels of both calbindin and vitamin D are attributed to the pathology of Alzheimer's disease. Further research on vitamin D via calbindin-CAMK-II signaling may provide newer insights, revealing novel therapeutic targets and strategies for treatment.