SP6616 as a Kv2.1 inhibitor efficiently ameliorates peripheral neuropathy in diabetic mice

Abstract

Background Diabetic peripheral neuropathy (DPN) is a common complication of diabetes severely afflicting the patients, while there is yet no effective medication against this disease. As Kv2.1 channel functions potently in regulating neurological disorders, the present work was to investigate the regulation of Kv2.1 channel against DPN-like pathology of DPN model mice by using selective Kv2.1 inhibitor SP6616 (ethyl 5-(3-ethoxy-4-methoxyphenyl)-2-(4-hydroxy-3-methoxybenzylidene)-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate) as a probe. Methods STZ-induced type 1 diabetic mice with DPN (STZ mice) were defined at 12 weeks of age (4 weeks after STZ injection) through behavioral tests, and db/db (BKS Cg- m +/+ Lepr db /J ) type 2 diabetic mice with DPN ( db/db mice) were at 18 weeks of age. SP6616 was administered daily via intraperitoneal injection for 4 weeks. The mechanisms underlying the amelioration of SP6616 on DPN-like pathology were investigated by RT-PCR, western blot and immunohistochemistry technical approaches against diabetic mice, and verified against the STZ mice with Kv2.1 knockdown in dorsal root ganglion (DRG) tissue by injection of adeno associated virus AAV9-Kv2.1-RNAi. Amelioration of SP6616 on the pathological behaviors of diabetic mice was assessed against tactile allodynia, thermal sensitivity and motor nerve conduction velocity (MNCV). Findings SP6616 treatment effectively ameliorated the threshold of mechanical stimuli, thermal sensitivity and MNCV of diabetic mice. Mechanism research results indicated that SP6616 suppressed Kv2.1 expression, increased the number of intraepidermal nerve fibers (IENFs), improved peripheral nerve structure and vascular function in DRG tissue. In addition, SP6616 improved mitochondrial dysfunction through Kv2.1/CaMKKβ/AMPK/PGC-1α pathway, repressed inflammatory response by inhibiting Kv2.1/NF-κB signaling and alleviated apoptosis of DRG neuron through Kv2.1-mediated regulation of Bcl-2 family proteins and Caspase-3 in diabetic mice. Interpretation Our work has highly supported the beneficial of Kv2.1 inhibition in ameliorating DPN-like pathology and highlighted the potential of SP6616 in the treatment of DPN. Funding Please see funding sources.

FX5, a non-steroidal glucocorticoid receptor antagonist, ameliorates diabetic cognitive impairment in mice

“…injection of 150 mg/kg STZ in 0.5 M sodium citrate buffer or vehicle. One week after injection, mice with blood glucose level higher than 16.7 mM were classified as T1DM (STZ) mice [ 34 ].…”

Jatrorrhizine ameliorates Schwann cell myelination via inhibiting HDAC3 ability to recruit Atxn2l for regulating the NRG1‐ErbB2‐PI3K‐AKT pathway in diabetic peripheral neuropathy mice

“…For this purpose, a series of von Frey filaments were applied to the plantar surface of the left hind paw with pressure, causing the filament to buckle. A paw withdrawal in response to each stimulus was recorded, and a 50% paw withdrawal threshold was calculated according to the published formula (Zhu et al, 2020). The motor nerve conduction velocity of the sciatic nerve was evaluated using orthodromic recording techniques, at least five readings per animal were taken at 15 min intervals, and the average reading was calculated.…”

Roles of AMPK and Its Downstream Signals in Pain Regulation

“…Painful or painless neuropathy or both can develop in patients with diabetes [ 121 , 122 , 123 ], and the generative mechanism(s) is complicated and is associated with multiple factors, such as the duration of diabetes and age [ 124 , 125 ]. Animal models usually develop hypersensitivity during the early stage of diabetes [ 10 , 126 ], whereas sensation is usually lost after long-term hyperglycemia [ 127 ]. Neuronal AMPK can be impaired from early stage of diabetes in mice [ 10 ].…”

“…Activating AMPK early during the course of diabetes can inhibit neuronal excitability and ameliorate hypersensitivity by downregulating membrane-associated TRPA1 in sensory neurons [ 10 , 40 ]. In contrast, AMPK activation can also enhance neuronal excitability and ameliorate hyposensitivity, including mechanical or thermal responses, by inhibiting the Kv2.1 channel in animal models of long-term diabetic neuropathy [ 127 ], suggesting a dual beneficial effect of AMPK activators such as metformin in patients with diabetes.…”