Both exogenous and endogenous cannabinoids can allosterically modulate glycine receptors (GlyRs). However, little is known about the molecular basis of cannabinoid-GlyR interactions. Here we report that sustained incubation with the endocannabinoid anandamide (AEA) substantially increased the amplitude of glycine-activated current in both rat cultured spinal neurons and in HEK-293 cells expressing human α1, rat α2 and α3 GlyRs. While the α1 and α3 subunits were highly sensitive to AEA-induced potentiation, the α2 subunit was relatively insensitive to AEA. Switching a serine at 296 and 307 in the TM3 (transmembrane domain 3) of the α1 and α3 subunits with an alanine (A) at the equivalent position in the α2 subunit converted the α1/α3 AEA-sensitive receptors to sensitivity resembling that of α2. The S296 residue is also critical for exogenous cannabinoid-induced potentiation of I Gly. The magnitude of AEA potentiation decreased with removal of either the hydroxyl or oxygen groups on AEA. While desoxy-AEA was...

Rationale: Cannabinergic compounds, such as THC and the endogenous cannabinoid, anandamide (AEA), can affect neurocognitive processes, including memory and attention. In particular, activation of cannabinoid receptors in prefrontal cortex causes deficit...

Despite the success of antiretroviral therapy in suppressing viral load, nearly half of the 37 million people infected with HIV experience cognitive and motor impairments, collectively classified as HIV-associated neurocognitive disorders (HAND). In the CNS, HIV-infected microglia release neurotoxic agents that act indirectly to elicit excitotoxic synaptic injury. HIV trans-activator of transcription (Tat) protein is one such neurotoxin that is thought to play a major role in the neuropathogenesis of HAND. The endocannabinoid (eCB) system provides on-demand neuroprotection against excitotoxicity, and exogenous cannabinoids attenuate neurotoxicity in animal models of HAND. Whether this neuroprotective system is altered in the presence of HIV is unknown. Here, we examined the effects of Tat on the eCB system in rat primary hippocampal cultures. Using whole-cell patch-clamp electrophysiology, we measured changes in retrograde eCB signaling following exposure to Tat. Treatment with Tat significantly reduced th...

Cannabis is the most widely used illicit drug in the US, and cannabis use among adolescents continues to rise. Some studies suggest that adolescent cannabis use increases the risk for depression, anxiety, and cognitive impairments later in life. In addi...

The active principle of marijuana, Δ9-tetrahydrocannabinol (THC), may regulate mood by hijacking an intrinsic cannabinoid-mediated mechanism involved in the control of emotions. In support of this hypothesis, pharmacological blockade of FAAH (fatty-acid amide hydrolase), an enzyme that hydrolyzes the endogenous cannabinoid anandamide, reduces anxiety-like behaviours in rats. These effects have not yet been identified, but they may involve activation of neurons in the dorsal raphe (DR) nucleus, a major source of serotonin in the mammalian brain. To test this possibility, we measured spontaneous firing activity in rats and mice DR neurons using in vivo recording techniques. Systemic administration of the potent and selective FAAH inhibitor URB597 (0.1 mg/kg, intravenous, i.v.) elicited a slow-onset increase in DR neuron firing, which became significant 20-140 min after drug injection (mean firing rate; vehicle: 1.45±0.1 Hz; URB597: 2.45±0.2 Hz; P < 0.01, n=55). This effect was prevented by the CB1 receptor a...

Eric Ziea1, Justin Wu1, Lixing Lao2, Tianhua Ren1, David Yew3, Joseph Sung1. Dept Med1, Anat3, Chin Univ Hong Kong. Center Integrat Med2, Univ Maryland,Baltimore. Childhood stress has been implicated as a contributing factor in irritable bowel syndrome(IBS).It has also been reported that neonatal maternal separation stress(NMSS) induces visceral hyperalgesia in rats, thus we used a colonic balloon distension(CBD) rat model to study the effect of NMSS on brain-gut axis neurochemical responses to nociceptive stimuli. Male neonatal SD rats were randomly divided into: 1.Maternal separation(MS;n=8) 3 hours/day on postnatal days 2-21 and 2.Non-handled control (n=8).CBD was performed on day 60 to assess abdominal withdrawal reflex (AWR),a marker of visceral pain. Pain threshold was defined as balloon pressure provoking a nociceptive AWR response to graded CBD. Substance P and serotonin (5-HT) expression along the brain-gut axis was evaluated by immunohistochemistry and ELISA.Pain threshold was significantly lower...

Recent studies revealed that cannabinoid CB1 receptors (CB1Rs) play important roles in the development of neural circuit formation and plasticity. In the rodent barrel cortex, CB1Rs at the thalamocortical terminals causes a developmental switch from lon...

The medial prefrontal cortex (mPFC) has been widely implicated in the contextual control of appetitive and aversive conditioning. Furthermore, the two subdomains within the mPFC, the infralimbic (IL) and prelimbic (PL), have been shown to differentially...

Endocannabinoids form a novel class of intercellular messengers, the functions of which include retrograde signaling in the brain and mediation or modulation of several types of synaptic plasticity. Yet, the signaling mechanisms and long-term effects of the stimulation of CB1 cannabinoid receptors (CB1-R) are poorly understood. We show that anandamide, 2-arachidonoyl-glycerol, and Δ9-tetrahydrocannabinol (THC) activated extracellular signal-regulated kinase (ERK) in hippocampal slices. In living mice, THC activated ERK in hippocampal neurons and induced its accumulation in the nuclei of pyramidal cells in CA1 and CA3. Both effects were attributable to stimulation of CB1-R and activation of MAP kinase/ERK kinase (MEK). In hippocampal slices, the stimulation of ERK was independent of phosphatidyl-inositol-3-kinase but was regulated by cAMP. The endocannabinoid-induced stimulation of ERK was lost in Fyn knock-out mice, in slices and in vivo , although it was insensitive to inhibitors of Src-family tyrosine ki...

1,1-Dimethylheptyl-delta-8-THC-11-oic acid (CT-3 or ajulemic acid) is a potent analog of THC-11-oic acid (the metabolite of THC). The apparent lack of psychotropic effects of CT-3 makes it an attractive candidate for therapeutic development. Here we extended the characterization of CT-3 to models of chronic inflammatory pain and neuropathic pain in rats, and investigated the mechanisms that contribute to the unique behavioral profile of CT-3. (1) Systemic administration of CT-3 was effective in suppressing thermal hyperalgesia in CFA-inflammed rats, and in reversing mechanical allodynia in the CCI model of neuropathic pain. (2) Peripheral administration of CT-3 (i.pl.) and intracerebral, but not intrathecal administration were effective in suppressing CFA-induced hyperalgesia. (3) In competition binding with [3H]SR141716A, CT-3 exhibited an approximate 4 fold higher Ki in spinal cord compared to brain membrane preparations. Likewise, in [S35]GTPgS binding assays, CT-3 behaved as a partial agonist in the br...