Biology subjects

Klein, A. H.

Publications and source records attributed to Klein, A. H..

5 recordsLinked to original sources

bioRxiv2026

Loss of SUR1 and Kir6.2 ATP-sensitive potassium channel subunits produces comparable neuronal excitability and morphine antinociception

ATP-sensitive potassium (KATP) channels are integral membrane proteins that play a crucial role in linking cellular metabolism to neuronal excitability. KATP channels in peripheral nociception and pain emphasize metabolic gating as a determinant of dorsal root ganglia and spinal cord excitability, particularly in pathophysiological states. Activation of KATP channels reduces excitability and and also contributes to opioid induced analgesia. KATP channels are composed of multiple subunits, that are assembled in several subtypes, including Kir6.2/SUR1 which is found predominantly in neurons in the nervous system. It remains unclear whether both Kir6.2 and SUR1 subunits are required to regulate neuronal excitability under naive conditions and to mediate morphine-induced antinociception. These experiments aim to determine whether neuron-specific loss of either Kir6.2 or SUR1 increases dorsal root ganglion (DRG) neuronal excitability, and attenuates morphine antinociception in mice. We found that loss of SUR1 or Kir6.2 activity or expression both increased DRG excitability in whole cell patch clamp studies. Using DRG cultured from SUR1 and Kir6.2 floxed animals, we also found that loss of either subunit decreased potassium flux induced by diazoxide. Morphine induced antinociception was also attenuated after Cre-mediated recombination in SUR1 and Kir6.2 floxed animals. Chronic morphine administration also decreased Kir6.2 (gene: Kcnj11) RNA signal in mouse DRG, but not spinal cords. Together, these findings suggest that, despite evidence from single-cell sequencing and other datasets indicating potentially distinct expression patterns of SUR1 and Kir6.2, these subunits most likely function cooperatively to form functional KATP channels under normal physiological conditions.

neuroscience↗

bioRxiv2023

Loss of ATP-sensitive channel expression and function decreases opioid sensitivity in a mouse model of type 2 diabetes

During diabetes, {beta}-cell dysfunction due to loss of potassium channels sensitive to ATP, known as KATP channels occurs progressively over time contributing to hyperglycemia. KATP channels are additionally present in the central and peripheral nervous systems and are downstream targets of opioid receptor signaling. The aim of this study is to investigate if KATP channel expression or activity in the nervous system changes in diabetic mice and if morphine antinociception changes in mice fed a high fat diet (HFD) for 16 weeks compared to controls. Mechanical thresholds were also monitored before and after administration of glyburide or nateglinide, KATP channel antagonists, for four weeks. HFD mice have decreased antinociception to systemic morphine, which is exacerbated after systemic treatment with glyburide or nateglinide. HFD mice also have lower rotarod scores, decreased mobility in an open field test, and lower burrowing behavior compared to their control diet counterparts, which is unaffected by KATP channel antagonist delivery. Expression of KATP channel subunits, Kcnj11 (Kir6.2) and Abcc8 (SUR1), were decreased in the peripheral and central nervous system in HFD mice, which is significantly correlated with baseline paw withdrawal thresholds. Upregulation of SUR1 through an adenovirus delivered intrathecally increased morphine antinociception in HFD mice, whereas Kir6.2 upregulation improved morphine antinociception only marginally. Perspective: This article presents the potential link between KATP channel function and neuropathy during diabetes. There is a need for increased knowledge in how diabetes affects structural and molecular changes in the nervous system to lead to the progression of chronic pain and sensory issues.

neuroscience↗

bioRxiv2022

KATP Channel Prodrugs Reduce Inflammatory and Neuropathic Hypersensitivity, Morphine Induced Hypersensitivity, and Precipitated Withdrawal in Mice

Previous studies show ATP-sensitive potassium (KATP) channel openers can reduce hypersensitivity associated with chronic pain models in rodents, and reduce morphine tolerance. Many agonists of KATP channels are not soluble in physiologically relevant vehicles, requiring adaptation for clinical use. This study compared the antinociception activity of novel KATP channel targeting prodrugs, CKLP1, CKLP2, and CF3-CKLP. These prodrugs are activated by endogenous alkaline phosphatase enzymes present in the peripheral and central nervous systems. Analgesic capabilities of intrathecally injected prodrugs were tested in rodent models of spinal nerve ligation (SNL) and Complete Freunds Adjuvant (CFA) as models for neuropathic and inflammatory pain, respectively. CKLP1 and CKLP2 significantly increased mechanical paw withdrawal thresholds 1-2 hours after intrathecal administration in the SNL model, but all three prodrugs were able to attenuate hypersensitivity up to 7 days after CFA treatment. The reduction of opioid tolerance and opioid-induced hypersensitivity in mice treated chronically with morphine was significantly reduced in CKLP1 and CKLP2 treated animals. Prodrug cleavage was confirmed in mouse spinal cords using liquid chromatography. These studies may aid in the further development of KATP channel prodrugs for use in treatments of chronic pain, opioid tolerance, and withdrawal.

pharmacology and toxicology↗

bioRxiv2020

Loss of SUR1 subtype KATP channels alters antinociception and locomotor activity after opioid administration

BackgroundOpioid signaling can occur through several downstream mediators and influence analgesia as well as reward mechanisms in the nervous system. KATP channels are downstream targets of the opioid receptor and contribute to morphine-induced antinociception. AimsThe aim of the present work was to assess the role of SUR1-subtype KATP channels in antinocicpetion and hyperlocomotion of synthetic and semi-synthetic opioids. MethodsAdult male and female mice wild-type (WT) and SUR1 deficient (KO) mice were assessed for mechanical and thermal antinociception after administration of either buprenorphine, fentanyl, or DAMGO. Potassium flux was assessed in the dorsal root ganglia and superficial dorsal horn cells in WT and KO mice. Hyperlocomotion was also assessed in WT and KO animals after buprenorphine, fentanyl, or DAMGO administration. ResultsSUR1 KO mice had attenuated mechanical antinociception after systemic administration of buprenorphine, fentanyl, and DAMGO. Potassium flux was also attenuated in the dorsal root ganglia and spinal cord cells after acute administration of buprenorphine and fentanyl. Hyperlocomotion after administration of morphine and buprenorphine was potentiated in SUR1 KO mice, but was not seen after administration of fentanyl or DAMGO. ConclusionsThese results suggest SUR1-subtype KATP channels mediate the antinociceptive response of several classes of opioids (alkaloid and synthetic/semi-synthetic), but may not contribute to the "drug-seeking" behaviors of all classes of opioids.

neuroscience↗

bioRxiv2020

Inhibition of the phosphoinositide 3-kinase-AKT-cyclic GMP-c-Jun N-terminal kinase signaling pathway attenuates the development of morphine tolerance in a mouse model of neuropathic pain

BackgroundOpioid management of chronic pain can cause opioid-induced analgesic tolerance and hyperalgesia, complicating clinical pain-management treatments. Research presented here sought to determine if opioid induced tolerance is linked to activity changes within the PI3K{gamma}-AKT-cGMP-JNK intracellular signaling pathway in spinal cord or peripheral nervous systems. MethodsMorphine or saline injections were given subcutaneously twice a day for five days (15 mg/kg) to male C57Bl6 mice. A separate cohort of mice received spinal nerve ligation (SNL) one week prior to the start of morphine tolerance. Afterwards, spinal cord, dorsal root ganglia, and sciatic nerves were isolated for quantifying total and phosphorylated-JNK levels, cGMP, and gene expression analysis. ResultsGene expression for the PI3K{gamma}-AKT-cGMP-JNK signaling pathway including, Akt1, Akt2, Akt3, Pik3cg, Pten, Jnk3, and nNos1 were decreased in the spinal cord with varied expression changes in the dorsal root ganglia and sciatic nerve of morphine tolerant and morphine tolerant mice after SNL. We observed significant increases in total and phosphorylated-JNK levels in the spinal cord, total JNK in dorsal root ganglia, and cGMP in the sciatic nerve of morphine tolerant mice with SNL. Pharmacological inhibition of PI3K, nNOS, or JNK, using thalidomide, quercetin, or SP600125, attenuated the development of morphine tolerance in mice with SNL as measured by thermal paw withdrawal. ConclusionsOverall, the PI3K/AKT intracellular signaling pathway is a potential target for reducing the development of morphine tolerance. Continued research into this pathway will contribute to the development of new analgesic drug therapies.

neuroscience↗