Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking

Abstract

Clavulanic acid is a CNS-modulating compound with exceptional blood-brain barrier permeability and safety profile. Clavulanic acid has been proposed to have anti-depressant activity and is currently entering Phase IIb clinical trials for the treatment of Major Depressive Disorder (MDD). Studies have also shown that clavulanic acid suppresses anxiety and enhances sexual functions in rodent and primate models by a mechanism involving central nervous system (CNS) modulation, although its detailed mechanism of action has yet to be elucidated. To further examine its potential as a CNS modulating agent as well as its mechanism of action, we investigated the effects of clavulanic acid in neuronal cells. Our results indicate that clavulanic acid enhances dopamine release in PC12 and SH-SY5Y cells without affecting dopamine synthesis. Furthermore, using affinity chromatography we were able to identify two proteins, Munc18-1 and Rab4 that potentially bind to clavulanic acid and play a critical role in neurosecretion and the vesicle trafficking process. Consistent with this result, an increase in the translocation of Munc18-1 and Rab4 from the cytoplasm to the plasma membrane was observed in clavulanic acid treated cells. Overall, these data suggest that clavulanic acid enhances dopamine release in a mechanism involving Munc18-1 and Rab4 modulation and warrants further investigation of its therapeutic use in CNS disorders, such as depression.

Clavulanic acid reduces rewarding, hyperthermic and locomotor-sensitizing effects of morphine in rats: A new indication for an old drug?

“…Further, the development of behavioral sensitization to morphine is thought to be more dependent on glutamate transmission than on dopamine transmission (Vanderschuren and Kalivas, 2000). Although it is somewhat difficult to reconcile the behavioral effects of CA observed here with its dopamine-enhancing effects (Sanna et al, 2013; Kost et al, 2011, 2012), it should be noted that our study used a dosing paradigm in which CA was administered repeatedly. This dosing paradigm was used because multiple laboratories have demonstrated that the preclinical activity of CTX in reducing the symptoms of CNS diseases is dependent on repeated administration (Rothstein et al, 2005; Sari et al, 2009, 2013; Rawls et al, 2007, 2010a, b; Tallarida et al, 2013; Trantham-Davidson et al, 2012).…”

“…Some of the effects of CTX are prevention of analgesic tolerance and physical dependence that develops during chronic morphine exposure (Rawls et al, 2007, 2010a, b), inhibition of opioid-induced hyperalgesia (Chen et al, 2012), inhibition of relapse to cocaine seeking (Knackstedt et al, 2010; Sari et al, 2009), inhibition of the direct reinforcing effects of cocaine in mice maintained under a progressive-ratio responding schedule (Ward et al, 2011), inhibition of locomotor sensitization produced by cocaine and amphetamine (Tallarida et al, 2013; Sondheimer and Knackstedt, 2011; Rasmussen et al, 2011), prevention of methamphetamine-induced CPP (Abulseoud et al, 2013), and reduction of alcohol consumption (Sari et al, 2013; Rao and Sari, 2012). Despite structural similarities between CA and CTX, and the more favorable pharmacokinetic and physiochemical properties of CA as related to CNS activity (Nakagawa et al, 1994; Bolton et al, 1986), the potential effectiveness of CA as a therapeutic for CNS diseases is limited to studies that have examined neuroprotection, anxiety, and erectile dysfunction (Kim et al, 2009; Kost et al, 2011, 2012; Sanna et al, 2013). To our knowledge, the present results are the first evidence that CA can disrupt rewarding and sensitizing effects of an addictive substance.…”

“…It is also in accordance with earlier work demonstrating that CTX inhibits locomotor sensitization produced by amphetamine (Rasmussen et al, 2011) and cocaine (Tallarida et al, 2013; Sondheimer and Knackstedt, 2011) and MS-153 inhibits behavioral sensitization produced by phencyclidine (Abekawa et al, 2002). Additional mechanisms of action that may have contributed to the efficacy of CA against morphine’s rewarding effects include enhancement of monoamine transmission and inhibition of glutamate carboxypeptidase II (GCPII), also known as NAALADase (Sanna et al, 2013; Banani et al, 2012; Kost et al, 2011). A role for 5-HT systems in the conditioned rewarding effects of morphine have been demonstrated previously, with activation of 5-HT 2 receptors producing inhibition and blockade of 5-HT 3 receptors causing enhancement (Nomikos and Spyraki, 1988; Acquas et al, 1988; Carboni et al, 1989; Higgins et al, 1992).…”

“…CA has also been shown to increase dopamine transmission (Kost et al, 2011; Sanna et al, 2013). While the possibility that CA increased dopamine transmission in the present experiments cannot be excluded, it is unlikely that such an increase, if it did occur, could have accounted for the efficacy of CA against morphine’s pharmacological effects.…”

Clavulanic acid enhances glutamate transporter subtype I (GLT-1) expression and decreases reinforcing efficacy of cocaine in mice

“…These inconsistencies between CA and CTX in cocaine SA acquisition experiments suggest that the two β-lactam-containing compounds act through mechanisms that may not be entirely identical. One example is the increase in dopamine transmission produced by CA (Kost et al 2011; Sanna et al 2013). Some direct dopamine agonists display a profile similar to CA in that they decrease the breaking points under PR conditions but increase, or have no effect, on cocaine SA under FR reinforcement schedules (Depoortere et al 1993).…”