Plasma orexin-A-like immunoreactivity levels and renal function in patients in a geriatric ward

Increased Expression of Orexin-A in Patients Affected by Polycystic Kidney Disease

Orexin-A is a neuropeptide product of the lateral hypothalamus that acts on two receptors, OX1R and OX2R. The orexinergic system is involved in feeding, sleep, and pressure regulation. Recently, orexin-A levels have been found to be negatively correlated with renal function. Here, we analyzed orexin-A levels as well as the incidence of SNPs in the hypocretin neuropeptide precursor (HCRT) and its receptors, HCRTR1 and HCRTR2, in 64 patients affected by autosomal dominant polycystic kidney disease (ADPKD) bearing truncating mutations in the PKD1 or PKD2 genes. Twenty-four healthy volunteers constituted the control group. Serum orexin-A was assessed by ELISA, while the SNPs were investigated through Sanger sequencing. Correlations with the main clinical features of PKD patients were assessed. PKD patients showed impaired renal function (mean eGFR 67.8 ± 34.53) and a statistically higher systolic blood pressure compared with the control group (p < 0.001). Additionally, orexin-A levels in PKD patients were statistically higher than those in healthy controls (477.07 ± 69.42 pg/mL vs. 321.49 ± 78.01 pg/mL; p < 0.001). Furthermore, orexin-A inversely correlated with blood pressure (p = 0.0085), while a direct correlation with eGFR in PKD patients was found. None of the analyzed SNPs showed any association with orexin-A levels in PKD. In conclusion, our data highlights the emerging role of orexin-A in renal physiology and its potential relevance to PKD. Further research is essential to elucidate the intricate mechanisms underlying orexin-A signaling in renal function and its therapeutic implications for PKD and associated cardiovascular complications.

Increased plasma orexin-A concentrations are associated with the non-motor symptoms in Parkinson's disease patients

BACKGROUND

Orexin, a neuropeptide primarily secreted by neurons in the lateral hypothalamus, has been implicated in Parkinson's disease (PD). Studies on the relationship between plasma orexin-A levels and PD are rare.

OBJECTIVES

This study aimed to assess levels of plasma orexin-A in the progression of PD and to evaluate the correlation between orexin-A levels and non-motor symptoms.

METHODS

Enzyme-linked immunosorbent assay was used to determine plasma orexin-A levels in 117 healthy controls and 121 PD patients, including those with early (n = 68), medium (n = 40) and advanced (n = 13) stages of the disease. Evaluation of motor symptoms and non-motor symptoms in PD patients, such as sleep disorders, cognitive dysfunction, neuropsychiatric symptoms, autonomic nervous dysfunction, hyposmia and PD-related pain, were assessed by the associated scales.

RESULTS

Plasma orexin-A levels were significantly higher in PD patients compared to healthy controls. Orexin-A levels were elevated in early-stage and medium-stage PD compared to healthy controls, but were decreased in advanced-stage PD. Orexin-A levels were negatively correlated with the Unified Parkinson's Disease Rating Scale Part III scores, disease duration, and dopamine receptor agonist doses, and were positively correlated with the Pittsburgh Sleep Quality Index, REM-sleep Behavior Disorder Questionnaire, 14-item Hamilton Anxiety Scale, Mini-Mental State Examination, and Non-motor Symptom Scale items 22-24 scores.

CONCLUSIONS

We found for the first time that plasma orexin-A levels were increased in early-stage and medium-stage PD and were decreased in advanced-stage PD. Furthermore, orexin-A levels were correlated with the non-motor symptoms of insomnia, REM-sleep behavior disorder, anxiety, cognitive dysfunction, and renal dysfunction.