In vivo silencing of the CaV3.2 T-type calcium channels in sensory neurons alleviates hyperalgesia in rats with streptozocin-induced diabetic neuropathy

Abstract

Earlier, we showed that streptozocin (STZ)-induced type 1 diabetes in rats leads to the development of painful peripheral diabetic neuropathy (PDN) manifested as thermal hyperalgesia and mechanical allodynia accompanied by significant enhancement of T-type calcium currents (T-currents) and cellular excitability in medium-sized dorsal root ganglion (DRG) neurons. Here, we studied the in-vivo and in-vitro effects of gene-silencing therapy specific for the Cav3.2 isoform of T-channels, on thermal and mechanical hypersensitivity, and T-current expression in small and medium-size DRG neurons of STZ-treated rats. We found that silencing of the T-channel Cav3.2 isoform using antisense oligonucleotides, had a profound and selective anti-hyperalgesic effect in diabetic rats and is accompanied by significant down-regulation of T-currents in DRG neurons. Anti-hyperalgesic effects of CaV3.2 antisense oligonucleotides in diabetic rats were similar in models of rapid and slow onset of hyperglycemia following intravenous and intraperitoneal injections of STZ, respectively. Furthermore, treatments of diabetic rats with daily insulin injections reversed T-current alterations in DRG neurons in parallel with reversal of thermal and mechanical hypersensitivity in-vivo. This confirms that CaV3.2 T-channels, important signal amplifiers in peripheral sensory neurons, may contribute to the cellular hyperexcitability that ultimately leads to the development of painful PDN.

Nanoparticle-encapsulated emodin decreases diabetic neuropathic pain probably via a mechanism involving P2X3 receptor in the dorsal root ganglia

“…Type 2 diabetic rat models were induced by a single intraperitoneal (i.p.) injection of 30 mg/kg streptozocin (STZ) and a diet of high calorie food [21,22]. STZ was dissolved in citrate buffer (pH 4.5).…”

“…After 7 days, blood samples were obtained from the tail vein, and glycaemia was determined using a glucometer. Fasting blood glucose > 200 mg/dl (11.1 mM) was considered a marker of DM [21,22]. Spontaneous pain behaviors were measured at 7 days after STZ injection.…”

“…The mechanical nociceptive threshold was evaluated by observing withdrawal responses to mechanical stimulation using von Frey filaments (Stoelting, Wood Dale, IL, USA) [22][23][24]. The von Frey filament was used to apply a linearly increasing pressure, starting at 0.13 g and increasing until a withdrawal response occurred.…”

“…The latency to hind paw withdrawal from a thermal stimulus was determined by exposing the plantar surface of the hind paw to radiant heat using the Thermal Paw Stimulation System (BME-410C, Tianjin, China) [22][23][24]. Rats were placed in a transparent, square, bottomless acrylic box (22 cm × 12 cm × 22 cm) on a glass plate under which a light was located.…”

Gasotransmitters in Vascular Complications of Diabetes

“…The T-type voltage-gated calcium channel Ca V 3.2 is sensitized by H 2 S, leading to increased pain sensitivity (101). An increased H 2 S tissue content and hyperactivity (102). Conversely, antinociceptive effects also have been reported for H 2 S. These effects were antagonized by the ATP-sensitive potassium (K ATP ) channel blocker glibenclamide and by NOS inhibition (103).…”