Fig 1: Mdh2 knockdown in the PVN reduces OXT neurons and impairs glucose metabolism(A) Schematic representation showing Mdh2 gene PVN-specific knockdown in mice (fed on a CD) using AAV-delivered shRNA.(B) Coronal section shows the site of virus injection in the PVN. Scale bars, 200 μm.(C) Body weight over 4 weeks after virus injection (n = 6 per group).(D) The average 24-h food intake measured over 3 consecutive days in the 4th week after virus injection.(E) Two-hour fasting blood glucose over 4 weeks after virus injection.(F and G) The curves of mice blood glucose changes (F) and area under curve (G) during IPGTT.(H and I) The curves of mice blood glucose changes (H) and area under curve (I) during intraperitoneal insulin tolerance test (IPITT).(J) Representative images show the expression of OXT in the PVN of control mice (left) and mice with PVN-specific knockout of the Mdh2 gene (right). Scale bars, 200 μm.(K) Quantification of the numbers of OXT neurons in the PVN.(L) BAT temperature in mice measured by infrared imaging.(M and N) Infrared thermal imaging within 4-h cold intervention at 4°C (M), and the BAT temperature statistics (N).(O) Schematic representation of temperature preference test (TPT).(P) The time distribution of mice during the TPT across different ambient temperatures (PVN-scram, n = 6; PVN-Mdh2−/−, n = 5).(Q) The statistics of the duration that mice spent in cold (10–22°C), warm (22–34°C) and hot (34–46°C) zones, respectively.(R and S) Blood glucose level in PVN-specific Mdh2 knockout mice (n = 6) and control mice (n = 6) after intraperitoneal injection of LW6 (R) and area under curve (S).(T) Schematic for a proposed hypothesis: central MDH2 serves as a glucose-sensing node regulating systemic glucose homeostasis. Under physiological conditions, elevated blood glucose suppresses hypothalamic MDH2 activity, which disinhibits PVNOXT neurons. Activated OXT neurons drive BAT thermogenesis via SNS efferent, promoting glucose uptake and restoring normoglycemia—a feedback loop ensuring balanced glucose control. In pathological states (e.g., T2D), chronic hyperglycemia disrupts this glucose-MDH2 feedback axis, resulting in dysfunctional MDH2-mediated regulation of PVNOXT neurons. This impairment blunts the thermogenic response to glucose surges, exacerbating hyperglycemia and creating a self-reinforcing metabolic dysregulation cycle. Data shown as mean ± SEM. ns, not significant, ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.See also Figure S6.
Fig 2: Administration of LW6 produces sustained hypoglycemia in a T2D mouse model(A) Changes in fasting blood glucose levels in mice before and 5 days after STZ injection (CD, n = 5; before i.p. STZ, n = 12; after i.p. STZ, n = 12).(B and C) Changes in blood glucose levels in mice over time (B) after intraperitoneal injection of DMSO (HFD+DMSO, n = 6) or LW6 (2 mg/kg, CD + LW6, n = 5; HFD+LW6, n = 6), and area under curve (C).(D) Daily body weight measurements during LW6 treatment (DMSO, n = 5; LW6, n = 6) in T2D mice.(E) The average 24-h food intake measured over 3 consecutive days.(F) Blood glucose levels following LW6 treatment. The last injection was performed on day 30.(G and H) The curves of blood glucose changes (G) and area under curve (H) during IPGTT.(I and J) The curves of blood glucose changes (I) and area under curve (J) during IPITT.(K–M) Infrared thermal imaging within 4-h cold exposure at 4°C (K) for BAT (L) and tail (M).(N) Enzymatic assay of MDH activity in BAT following systemic DMSO or LW6 administration (n = 5 per group).(O and P) Protein expression and quantification MDH2 content following systemic DMSO or LW6 administration (n = 4 per group). Data shown as mean ± SEM. ns, not significant, ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.
Fig 3: Brain infusion of MDH2 antagonist ameliorates hyperglycemia in mice and rats(A) Schematic illustration of cannula used to inject LW6 (MDH2 antagonist, 1.5 mM) into the third ventricle (3V) of mice (fed on an HFD).(B) Coronal histology section showing the cannula track. Scale bars, 500 μm.(C and D) Western blot analysis showing the MDH2 protein expression levels (C) and corresponding statistical quantification (D) after DMSO (n = 3) or LW6 (n = 3) injection into the 3V of mice.(E) Timeline for assessing glucose metabolism following LW6 treatment.(F and G) Effects of DMSO (n = 8) or LW6 (n = 8) treatment on blood glucose levels over time in mice (F), and area under curve (G).(H) Changes in blood glucose levels before and 15 min after treatment with DMSO or LW6.(I) Plasma insulin levels measured 15 min after brain infusion of DMSO (n = 7) or LW6 (n = 7).(J and K) Changes in blood glucose levels over time in mice (J) and area under curve (K) during IPGTT.(L) Schematic illustrating the brain delivery of LW6 (10 mM) into the 3V of Sprague-Dawley (SD) rats (fed on a CD).(M and N) Effects of DMSO (n = 7) or LW6 (n = 7) treatment on blood glucose levels over time in rats (M), and area under curve (N).(O) Plasma insulin levels 1 h after 3V LW6 administration in rats (n = 6 per group).(P and Q) Changes in blood glucose levels over time (P) and area under curve (Q) during IPGTT following DMSO or LW6 treatment (n = 7 per group). Data shown as mean ± SEM. ns, not significant, ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.See also Figures S2 and S3.
Fig 4: RYGB surgery improves glucose metabolism in T2D and decreases CSF MDH2 level(A) Schematic illustration of the experimental design for profiling CSF proteome after RYGB surgery in a diet-induced obese diabetic rat model. Zucker diabetic fatty (ZDF) rats were fed a high-fat diet (HFD) or chow diet (CD) (CD lean, n = 8) for 8 weeks. The obese rats underwent either Roux-en-Y gastric bypass (RYGB) surgery (HFD+RYGB, n = 8) or sham surgery (HFD+Sham, n = 8). The rats were fed with the corresponding diet for 6 weeks, and cerebrospinal fluid (CSF) was collected for differential protein expression analysis.(B–D) The food intake (B), changes in body weight (C), and blood glucose levels (D) before and after the surgery and their trends over time, and the intergroup comparison at the 6th week after the surgery.(E and F) Intraperitoneal glucose tolerance tests (IPGTT) at 1 week before the surgery (E) and the 6th week after the surgery (F).(G) Venn diagram showing the number of differentially expressed proteins (DEPs) among CD lean, HFD+RYGB, and HFD+Sham groups.(H) Heatmap displaying protein expression profiles for individual rats across three groups.(I) Gene Ontology (GO) enrichment analysis of DEPs between HFD+RYGB and HFD+Sham groups.(J) Ranked p values for shared DEPs identified in HFD+RYGB vs. HFD+Sham and CD lean vs. HFD+Sham comparisons, excluding DEPs found in CD lean vs. HFD+RYGB.(K) Comparison of MDH2 protein expression levels among CD lean group, HFD+RYGB group, and HFD+Sham group (n = 6 in each group). Data shown as mean ± SEM. ns, not significant, ∗∗∗∗p < 0.0001.See also Figure S1.
Supplier Page from Abcam for Recombinant mouse MDH2 protein (Active) (His tag N-Terminus)