Metabotropic glutamate type 5 receptor binding availability during dextroamphetamine sensitization in mice and humans

Mesocorticolimbic function in cocaine polydrug users: A multimodal study of drug cue reactivity and cognitive regulation

Addictions are thought to be fostered by the emergence of poorly regulated mesocorticolimbic responses to drug-related cues. The development and persistence of these responses might be promoted by altered glutamate transmission, including changes to type 5 metabotropic glutamate receptors (mGluR5s). Unknown, however, is when these changes arise and whether the mGluR5 and mesocorticolimbic alterations are related. To investigate, non-dependent cocaine polydrug users and cocaine-naïve healthy controls underwent a positron emission tomography scan (15 cocaine users and 14 healthy controls) with [11 C]ABP688, and a functional magnetic resonance imaging scan (15/group) while watching videos depicting activities with and without cocaine use. For some drug videos, participants were instructed to use a cognitive strategy to lower craving. Both groups exhibited drug cue-induced mesocorticolimbic activations and these were larger in the cocaine polydrug users than healthy controls during the session's second half. During the cognitive regulation trials, the cocaine users' corticostriatal responses were reduced. [11 C]ABP688 binding was unaltered in cocaine users, relative to healthy controls, but post hoc analyses found reductions in those with 75 or more lifetime cocaine use sessions. Finally, among cocaine users (n = 12), individual differences in prefrontal [11 C]ABP688 binding were associated with midbrain and limbic region activations during the regulation trials. Together, these preliminary findings raise the possibility that (i) recreational polydrug cocaine users show biased brain processes towards cocaine-related cues and (ii) repeated cocaine use can lower cortical mGluR5 levels, diminishing the ability to regulate drug cue responses. These alterations might promote susceptibility to addiction and identify early intervention targets.

The combined analgesic, sedative, and anti-gastric cancer mechanisms of Tinospora sagittata var. yunnanensis (S. Y. Hu) H. S. Lo based on integrated ethnopharmacological data

ETHNOPHARMACOLOGY RELEVANCE

As a Yi medicine for eliminating wind to relieve pain, Tinospora sagittata var. yunnanensis (S. Y. Hu) H. S. Lo (TSY) is widely used to treat sore throat, stomach pain, bone and muscle injuries, and tumors; however, the material basis and mechanism of action remain unclear.

AIM OF THE STUDY

This study aims to investigate the potential active compounds of TSY and related pharmacological mechanisms against gastric cancer using a multitarget strategy.

MATERIALS AND METHODS

The main chemical components of TSY were collected through a literature review and database searches. The components were further screened for ADMET properties, and their targets were predicted using network pharmacology (admetSAR) and substructure-drug-target network-based inference (SDTNBI) approaches in silico. The pharmacological mechanism of action of TSY extract for pain relief, sedation, and anti-gastric cancer activities were identified via in vivo and in vitro biochemical analyses.

RESULTS

Here, 28 chemical components were identified, 7 active compounds were selected, and 75 targets of TSY extract were predicted. A compound-target-disease network topological approach revealed that the predicted targets are highly related to the digestive system and nervous system. Network pharmacology results suggested that the anti-gastric cancer activity of TSY was highly correlated with its analgesic and sedative targets and MAPK. In vivo experiments confirmed that TSY extract not only reduced the number of voluntary activities in the mouse model but also exhibited a synergistic effect on sodium pentobarbital-induced sleep, reduced the number of mice exhibiting writhing responses to acetic acid, and increased the hot plate pain threshold of mice. Thus, TSY extract exhibits good analgesic and sedative effects. The TSY extract inhibited HGC-27 cell proliferation and induced apoptosis by regulating apoptotic proteins (BAX, BCL-2 and BCL-XL) in vitro.

CONCLUSIONS

TSY exhibits combined analgesic, sedative, and anti-gastric cancer activities.

Clinical investigations of compounds targeting metabotropic glutamate receptors

Pharmacological modulation of glutamate has long been considered to be of immense therapeutic utility. The metabotropic glutamate receptors (mGluRs) are potential targets for safely altering glutamate-driven excitation. Data support the potential therapeutic use of mGluR modulators in the treatment of anxiety, depression, schizophrenia, and other psychiatric disorders, pain, epilepsy, as well as neurodegenerative and neurodevelopmental disorders. For each of the three mGluR groups, compounds have been constructed that produce either potentiation or functional blockade. PET ligands for mGlu5Rs have been studied in a range of patient populations and several mGlu5R antagonists have been tested for potential efficacy in patients including mavoglurant, diploglurant, basimglurant, GET 73, and ADX10059. Efficacy with mGlu5R antagonists has been reported in trials with patients with gastroesophageal reflux disease; data from patients with Parkinson's disease or Fragile X syndrome have not been as robust as hoped. Fenobam was approved for use as an anxiolytic prior to its recognition as an mGlu5R antagonist. mGlu2/3R agonists (pomaglumated methionil) and mGlu2R agonists (JNJ-40411813, AZD 8529, and LY2979165) have been studied in patients with schizophrenia with promising but mixed results. Antagonists of mGlu2/3Rs (decoglurant and TS-161) have been studied in depression where TS-161 has advanced into a planned Phase 2 study in treatment-resistant depression. The Group III mGluRs are the least developed of the mGluR receptor targets. The mGlu4R potentiator, foliglurax, did not meet its primary endpoint in patients with Parkinson's disease. Ongoing efforts to develop mGluR-targeted compounds continue to promise these glutamate modulators as medicines for psychiatric and neurological disorders.

mGlu5 receptor availability in youth at risk for addictions: effects of vulnerability traits and cannabis use

The excitatory neurotransmitter glutamate has been implicated in experience-dependent neuroplasticity and drug-seeking behaviors. Type 5 metabotropic glutamate (mGlu5) receptors might be particularly important. They are critically involved in synaptic plasticity and their availability has been reported to be lower in people with alcohol, tobacco, and cocaine use disorders. Since these reductions could reflect effects of drug use or pre-existing traits, we used positron emission tomography to measure mGlu5 receptor availability in young adults at elevated risk for addictions. Fifty-nine participants (age 18.5 ± 0.6) were recruited from a longitudinal study that has followed them since birth. Based on externalizing traits that predict future substance use problems, half were at low risk, half were at high risk. Cannabis use histories varied markedly and participants were divided into three subgroups: zero, low, and high use. Compared to low risk volunteers, those at elevated risk had lower [11C]ABP688 binding potential (BPND) values in the striatum, amygdala, insula, and orbitofrontal cortex (OFC). Cannabis use by risk group interactions were observed in the striatum and OFC. In these regions, low [11C]ABP688 BPND values were only seen in the high risk group that used high quantities of cannabis. When these high risk, high cannabis use individuals were compared to all other participants, [11C]ABP688 BPND values were lower in the striatum, OFC, and insula. Together, these results provide evidence that mGlu5 receptor availability is low in youth at elevated risk for addictions, particularly those who frequently use cannabis.