Decreased Serum Oxytocin and Increased Homocysteine in First-Episode Schizophrenia Patients

Abstract

Schizophrenia (SZ) is a debilitating and heterogeneous disease. We hypothesized that the oxytocin (OXT) system, inflammation and one-carbon metabolism would have a link with SZ. In this study, serum OXT, OXT receptor (OXTR), interleukin-6 (IL-6), high sensitivity CRP (hsCRP) and homocysteine (Hcy) levels were measured in 52 first-episode schizophrenia (FES) patients and 41 healthy controls (HC) from the Second Xiangya Hospital of Central South University. Meanwhile, the mRNA expressions of OXT and OXTR genes were determined by real-time quantitative PCR. Serum OXT and OXTR levels were significantly lower in FES patients (518.96 ± 22.22 and 174.60 ± 17.11 pg/ml) than the HC group (711.58 ± 40.57 and 252.15 ± 20.62 pg/ml). Serum IL-6 and hsCRP levels showed no difference between the two groups (1.82 ± 0.30 vs. 1.69 ± 0.36 pg/ml, 0.66 (0.22, 1.07) vs. 0.31 (0.13, 0.91) mg/L), but serum Hcy levels were significantly higher in FES patients (20.18 ± 1.83 vs. 15.24 ± 0.82 μmol/ml). The FES patients (0.27 ± 0.02 and 0.20 ± 0.02) have relatively higher mRNA expressions of OXT and OXTR genes than the HC group (0.16 ± 0.01 and 0.14 ± 0.01). In summary, our results suggested the possible function of the OXT system and Hcy in the pathogenesis of SZ.

Unveiling the Metabolic Profile of First-Episode Drug-Naïve Schizophrenia Patients: Baseline Characteristics of a Longitudinal Study Among Han Chinese

“…Our results also showed that FEDN patients had higher prevalence of hyperhomocysteinemia and hyperprolactinemia. Previous studies have also shown significantly increased HC and PRL levels in antipsychotic-naïve schizophrenia and related disorders (11,20). For example, Kirkpatrick et al (13) reported significant differences in PRL levels in patients with schizophrenia compared with controls.…”

“…On phase 3, all participants were invited to provide a blood sample for laboratory tests, including uric acid (UA), homocysteine (HC), total cholesterol (TC), triglyceride (TG) and prolactin (PRL). Previous studies have reported that first-episode schizophrenia populations present with decreased UA levels, increased HC, TC, TG and PRL levels (9)(10)(11)(12)(13). Considering that a substantial body of evidence has accumulated that indicates hypouricemia (40,41), hyperhomocysteinemia (42), hypercholesterolemia (43), hypertriglyceridemia (44) and hyperprolactinemia (45) are associated with cardiovascular risk, it was necessary to investigate hypouricemia, hyperhomocysteinemia, hypercholesterolemia, hypertriglyceridemia and hyperprolactinemia in these patients.…”

“…Moreover, MAs have been associated with poorer functional outcomes (5), worse quality of life (6, 7), and non-compliance with antipsychotic therapy (8) in this group of individuals. Interestingly, previous studies showed that first-episode schizophrenia populations without or minimal antipsychotic exposure present with higher prevalence of MAs, including lipid profile disturbances, reduced uric acid levels, elevated homocysteine and prolactin levels (9)(10)(11)(12)(13). Until now, the underlying mechanism of increased subthreshold metabolic dysregulation in schizophrenia is still unclear.…”

Oxytocin in Schizophrenia: Pathophysiology and Implications for Future Treatment

“…Results from the study of endogenous oxytocin levels in schizophrenia are mixed. Endogenous peripheral (measured in serum or plasma) oxytocin levels in patients with schizophrenia are lower than those in the healthy population [ 80 , 81 , 82 , 83 , 84 , 85 ], although several studies reported opposite findings [ 86 , 87 ] or no differences [ 88 , 89 ]. Two studies published in the 1980s found that cerebrospinal fluid oxytocin levels are higher in schizophrenia than in the healthy population [ 90 , 91 ], but another study found no difference in levels between individuals with or without schizophrenia [ 92 ].…”

Nicotinamide N-Methyltransferase: Genomic Connection to Disease

“…Regarding the first of these strands of evidence, there is little doubt that in the cases of bipolar disorder, 71 epilepsy, 45,72 and schizophrenia, [73][74][75] levels of homocysteine and its oxidation product, homocystine, are elevated. This evidence spans many years and too many references for all to be reviewed here.…”