Conotoxin contulakin-G engages a neurotensin receptor 2/R-type calcium channel (Cav2.3) pathway to mediate spinal antinociception

Hungry for relief: Potential for neurotensin to address comorbid obesity and pain

Chronic pain and obesity frequently occur together. An ideal therapy would alleviate pain without weight gain, and most optimally, could promote weight loss. The neuropeptide neurotensin (Nts) has been separately implicated in reducing weight and pain but could it be a common actionable target for both pain and obesity? Here we review the current knowledge of Nts signaling via its receptors in modulating body weight and pain processing. Evaluating the mechanism by which Nts impacts ingestive behavior, body weight, and analgesia has potential to identify common physiologic mechanisms underlying weight and pain comorbidities, and whether Nts may be common actionable targets for both.

Pronociceptive role of spinal Cav2.3 (R-type) calcium channels in a mouse model of postoperative pain

BACKGROUND

More than 80% of patients may experience acute pain after a surgical procedure, and this is often refractory to pharmacological intervention. The identification of new targets to treat postoperative pain is necessary. There is an association of polymorphisms in the Cav2.3 gene with postoperative pain and opioid consumption. Our study aimed to identify Cav2.3 as a potential target to treat postoperative pain and to reduce opioid-related side effects.

EXPERIMENTAL APPROACH

A plantar incision model was established in adult male and female C57BL/6 mice. Cav2.3 expression was detected by qPCR and suppressed by siRNA treatment. The antinociceptive efficacy and safety of a Cav2.3 blocker-alone or together with morphine-was also assessed after surgery.

KEY RESULTS

Paw incision in female and male mice caused acute nociception and increased Cav2.3 mRNA expression in the spinal cord but not in the incised tissue. Intrathecal treatment with siRNA against Cav2.3, but not with a scrambled siRNA, prevented the development of surgery-induced nociception in both male and female mice, with female mice experiencing long-lasting effects. High doses of i.t. SNX-482, a Cav2.3 channel blocker, or morphine injected alone, reversed postoperative nociception but also induced side effects. A combination of lower doses of morphine and SNX-482 mediated a long-lasting reversal of postsurgical pain in female and male mice.

CONCLUSION

Our results demonstrate that Cav2.3 has a pronociceptive role in the induction of postoperative pain, indicating that it is a potential target for the development of therapeutic approaches for the treatment of postoperative pain.

Venom-inspired somatostatin receptor 4 (SSTR4) agonists as new drug leads for peripheral pain conditions

Persistent pain affects one in five people worldwide, often with severely debilitating consequences. Current treatment options, which can be effective for mild or acute pain, are ill-suited for moderate-to-severe persistent pain, resulting in an urgent need for new therapeutics. In recent years, the somatostatin receptor 4 (SSTR 4 ), which is expressed in sensory neurons of the peripheral nervous system, has emerged as a promising target for pain relief. However, the presence of several closely related receptors with similar ligand-binding surfaces complicates the design of receptor-specific agonists. In this study, we report the discovery of a potent and selective SSTR 4 peptide, consomatin Fj1, derived from extensive venom gene datasets from marine cone snails. Consomatin Fj1 is a mimetic of the endogenous hormone somatostatin and contains a minimized binding motif that provides stability and drives peptide selectivity. Peripheral administration of synthetic consomatin Fj1 provided analgesia in mouse models of postoperative and neuropathic pain. Using structure-activity studies, we designed and functionally evaluated several Fj1 analogs, resulting in compounds with improved potency and selectivity. Our findings present a novel avenue for addressing persistent pain through the design of venom-inspired SSTR 4 -selective pain therapeutics.

One Sentence Summary

Venom peptides from predatory marine mollusks provide new leads for treating peripheral pain conditions through a non-opioid target.

Neurotensin and Neurotensin Receptors in Stress-related Disorders: Pathophysiology & Novel Drug Targets

Neurotensin (NT) is a 13-amino acid neuropeptide widely distributed in the CNS that has been involved in the pathophysiology of many neural and psychiatric disorders. There are three known neurotensin receptors (NTSRs), which mediate multiple actions, and form the neurotensinergic system in conjunction with NT. NTSR1 is the main mediator of NT, displaying effects in both the CNS and the periphery, while NTSR2 is mainly expressed in the brain and NTSR3 has a broader expression pattern. In this review, we bring together up-to-date studies showing an involvement of the neurotensinergic system in different aspects of the stress response and the main stress-related disorders, such as depression and anxiety, post-traumatic stress disorder (PTSD) and its associated symptoms, such as fear memory and maternal separation, ethanol addiction, and substance abuse. Emphasis is put on gene, mRNA, and protein alterations of NT and NTSRs, as well as behavioral and pharmacological studies, leading to evidence-based suggestions on the implicated regulating mechanisms as well as their therapeutic exploitation. Stress responses and anxiety involve mainly NTSR1, but also NTSR2 and NTSR3. NTSR1 and NTSR3 are primarily implicated in depression, while NTSR2 and secondarily NTSR1 in PTSD. NTSR1 is interrelated with substance and drug abuse and NTSR2 with fear memory, while all NTSRs seem to be implicated in ethanol consumption. Some of the actions of NT and NTSRs in these pathological settings may be driven through interactions between NT and corticotrophin releasing factor (CRF) in their regulatory contribution, as well as by NT's pro-inflammatory mediating actions.

Targeting sensory neuron GPCRs for peripheral neuropathic pain

Despite the high prevalence of peripheral neuropathic pain (NP) conditions and significant progress in understanding its underlying mechanisms, the management of peripheral NP remains inadequate. Existing pharmacotherapies for NP act primarily on the central nervous system (CNS) and are often associated with CNS-related adverse effects, limiting their clinical effectiveness. Mounting preclinical evidence indicates that reducing the heightened activity in primary sensory neurons by targeting G-protein-coupled receptors (GPCRs), without activating these receptors in the CNS, relieves pain without central adverse effects. In this review, we focus on recent advancements in GPCR-mediated peripheral pain relief and discuss strategies to advance the development of more effective and safer therapies for peripheral NP by shifting from traditional CNS modulatory approaches toward selective targeting of GPCRs on primary sensory neurons.

Current Drug Development Overview: Targeting Voltage-Gated Calcium Channels for the Treatment of Pain

Voltage-gated calcium channels (VGCCs) are targeted to treat pain conditions. Since the discovery of their relation to pain processing control, they are investigated to find new strategies for better pain control. This review provides an overview of naturally based and synthetic VGCC blockers, highlighting new evidence on the development of drugs focusing on the VGCC subtypes as well as mixed targets with pre-clinical and clinical analgesic effects.

The Options for Neuraxial Drug Administration

Neuraxial drug administration, i.e., the injection of drugs into the epidural or intrathecal space to produce anesthesia or analgesia, is a technique developed more than 120 years ago. Today, it still is widely used in daily practice in anesthesiology and in acute and chronic pain therapy. A multitude of different drugs have been introduced for neuraxial injection, only a part of which have obtained official approval for that indication. A broad understanding of the pharmacology of those agents is essential to the clinician to utilize them in a safe and efficient manner. In the present narrative review, we summarize current knowledge on neuraxial anatomy relevant to clinical practice, including pediatric anatomy. Then, we delineate the general pharmacology of neuraxial drug administration, with particular attention to specific aspects of epidural and intrathecal pharmacokinetics and pharmacodynamics. Furthermore, we describe the most common clinical indications for neuraxial drug administration, including the perioperative setting, obstetrics, and chronic pain. Then, we discuss possible neurotoxic effects of neuraxial drugs, and moreover, we detail the specific properties of the most commonly used neuraxial drugs that are relevant to clinicians who employ epidural or intrathecal drug administration, in order to ensure adequate treatment and patient safety in these techniques. Finally, we give a brief overview on new developments in neuraxial drug therapy.