View metadata, citation and similar papers at core.ac.uk brought to you by CORE ORIGINAL RESEARCH ARTICLEprovided by Frontiers - Publisher Connector published: 01 December 2014 doi: 10.3389/fnmol.2014.00094 Age dependence of the rapid antidepressant and synaptic effects of acute NMDA receptor blockade Elena Nosyreva, Anita E. Autry, Ege T. Kavalali and Lisa M. Monteggia* Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA Edited by: Ketamine is a N-methyl-D-aspartate receptor (NMDAR) antagonist that produces rapid Kimberly Raab-Graham, University of antidepressant responses in individuals with major depressive disorder.The antidepressant Texas at Austin, USA action of ketamine has been linked to blocking NMDAR activation at rest, which inhibits Reviewed by: eukaryotic elongation factor 2 kinase leading to desuppression of protein synthesis and Kuei-YuanTseng, Rosalind Franklin University, USA synaptic potentiation in the CA1 region of the hippocampus. Here, we investigated ChiHye Chung, Konkuk University, ketamine mediated antidepressant response and the resulting synaptic potentiation in South Korea juvenile animals. We found that ketamine did not produce an antidepressant response *Correspondence: in juvenile animals in the novelty suppressed feeding or the forced swim test. In addition Lisa M. Monteggia, Department of ketamine application failed to trigger synaptic potentiation in hippocampal slices obtained Neuroscience, University of Texas Southwestern Medical Center, 5323 from juvenile animals, unlike its action in slices from adult animals.The inability of ketamine Harry Hines Boulevard, Dallas, to trigger an antidepressant response or subsequent synaptic plasticity processes suggests TX 75390-9111, USA a developmental component to ketamine mediated antidepressant efficacy. We also show e-mail: lisa.monteggia@ utsouthwestern.edu that the NMDAR antagonist AP5 triggers synaptic potentiation in mature hippocampus similar to the action of ketamine, demonstrating that global competitive blockade of NMDARs is sufficient to trigger this effect. These findings suggest that global blockade of NMDARs in developmentally mature hippocampal synapses are required for the antidepressant efficacy of ketamine. Keywords: antidepressant, ketamine, behavior, synaptic potentiation, development INTRODUCTION Nosyreva et al., 2013). The behavioral as well as the synaptic Major depressive disorder (MDD) is a serious mental condition in effects of ketamine are dependent on the function of eukary- which there is a need for fast acting treatment. Ketamine, a non- otic elongation factor 2 (eEF2) kinase and protein synthesis as competitive N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine failed to elicit a behavioral response or potentiation has been shown to elicit a rapid antidepressant response in patients on the eEF2 kinase null mice as well as after application of pro- with MDD (Berman et al., 2000; Zarate et al., 2006; Price et al., tein translation blocker anisomycin (Autry et al., 2011; Nosyreva 2009) and bipolar depression (Diazgranados et al., 2010a; Zarate et al., 2013). Although these studies have provided a strong cor- et al., 2012). Ketamine has also been reported to have rapid anti- relation between the synaptic action of ketamine and its rapid suicidal effects (Price et al., 2009; DiazGranados et al., 2010b; antidepressant effects, they have not yet addressed whether this Larkin and Beautrais, 2011; Zarate et al., 2012), an area of crit- effect is dependent on the stage of synapse development. Synaptic ical unmet need. However, ketamine does not present an ideal plasticity related processes are age dependent and their proper- profile as an antidepressant due to its potential psychotomimetic ties vary during synapse development. For instance, NMDAR effects as well as abuse potential. Thus, there has been interest in only postsynaptically silent synapses are more prevalent dur- delineating the cellular mechanisms that underlie ketamine action ing earl stages of synapse development (Wu et al., 1996; Hanse to facilitate development of safer compounds with similar robust et al., 2013). We therefore examined whether ketamine elicits an and rapid antidepressant effects. antidepressant response and triggers similar synaptic potentia- In recent work, the antidepressant effect of ketamine have tion in juvenile animals to that previously observed in adults. been recapitulated in animal models predictive of antidepres- In addition, these earlier studies have not addressed whether the sant efficacy (Maeng et al., 2008; Li et al., 2010; Autry et al., 2011; synaptic effect of ketamine and another use-dependent NMDAR Nosyreva et al., 2013; Gideons et al., 2014), such as the forced blocker MK-801 could be mimicked by the widely used com- swim test (FST), the novelty suppressed feeding (NSF) test, and petitive non-use dependent NMDAR antagonist D-AP5 [D-AP5 learned helplessness test. In parallel, in hippocampal slices we (2R)-amino-5-phosphonopentanoate]. have also observed a form of synaptic potentiation elicited after In this study, we report that ketamine does not trigger a 30-min application of ketamine in the absence of stimulation. behavioral antidepressant response in juvenile animals as it does After ketamine application at rest, we stimulated the Schaffer col- in adults. We also find that ketamine does not trigger synap- lateral/commissural afferents and recorded postsynaptic responses tic potentiation in juvenile animals, demonstrating that the from CA1 dendrites. These responses were significantly enhanced antidepressant and synaptic effects of ketamine require the estab- after ketamine treatment in adult rats and mice (Autry et al., 2011; lishment of mature synaptic contacts. In addition, we show Frontiers in Molecular Neuroscience www.frontiersin.org December 2014 | Volume 7 | Article 94 | 1 Nosyreva et al. Age dependence of rapid antidepressant action that the competitive NMDAR antagonist D-AP5, elicits synaptic EXTRACELLULAR FIELD POTENTIAL RECORDINGS potentiation in developmentally mature slices complementing the Hippocampal slices (400 μm) were prepared from 14 to 21 day earlier observation that the competitive NMDAR antagonist 3- (young) or 6–8 week (adult) old Sprague Dawley rats, as indi- [(R)-2-Carboxypiperazin-4-yl]-propyl-1-phosphonic acid (CPP) cated. Animals were anesthetized with isoflurane and decapitated triggers a rapid antidepressant response in vivo (Autry et al., 2011). soon after the disappearance of corneal reflexes. The brain was removed, dissected, and then sliced using a vibratome (VT 1000S, MATERIALS AND METHODS Leica) in ice–cold dissection buffer containing the following (in ANIMALS mM): 2.6 KCl, 1.25 NaH2PO4, 26 NaHCO3, 0.5 CaCl2, 5 MgCl2, Male C57BL/6 mice from Jackson Labs and male Sprague–Dawley 212 sucrose, and 10 dextrose. Area CA3 was surgically removed rats from Charles River were obtained. For the experimental from each slice immediately after sectioning. The slices were paradigms, mice were 4 weeks of age and rats were either 2–3 transferred into a reservoir chamber filled with ACSF contain- (developmentally immature/juvenile) or 6–8 (developmentally ing the following (in mM): 124 NaCl, 5 KCl, 1.25 NaH2PO4, mature, young adult) weeks of age (McCutcheon and Marinelli, 26 NaHCO3,2CaCl2, 2 MgCl2, and 10 dextrose. Slices were 2009). Animals were maintained on a 12-h light/dark cycle with ad allowedtorecoverfor2–3hat30◦C. ACSF and dissection buffer libitum access to food and water, except when indicated. All exper- were equilibrated with 95% O2 and 5% CO2. For recording, iments were conducted and analyzed blind to treatment group. slices were transferred to a submerged recording chamber, main- Experiments were approved by the Institutional Animal Care and tained at 30◦C, and perfused continuously with ACSF at a rate of Use Committee at the UT Southwestern Medical Center. 2–3 ml/min. Field potentials were recorded with extracellular recording elec- DRUG TREATMENT trodes (1 M) filled with ACSF and placed in stratum radiatum of Ketamine (Fort Dodge Animal Health) and D-AP5 [D-(-)-2- area CA1. FPs were evoked by monophasic stimulation (duration, Amino-5-phosphonopentanoic acid] (Abcam Biochemicals) were 200 μs) of Schaffer collateral/commissural afferents with a con- prepared fresh in artificial cerebral spinal fluid (ACSF) and added centric bipolar tungsten stimulating electrode (Frederick Haer). to solutions as indicated. D-AP5, the active isomer of AP5, Stable baseline responses were collected every 30 s using a stim- was used to avoid potential variability associated with a racemic ulation intensity (10–30 μA), yielding 50–60% of the maximal mixture. The behavioral experiments utilized mice that were response. FPs were filtered at 2 kHz and digitized at 10 kHz on intraperitoneal (i.p.) injected drug to more closely mimic the route a personal computer using custom software (LabVIEW, National of administration in humans. For the field potentials (FPs) record- Instruments). Synaptic strength was measured as the initial slope ings, after 20 min of stable baseline, drugs (ketamine, D-AP5) (10–40% of the rising phase) of the FP. The group data were ana- were applied for 30 min at rest and then one control stimulus lyzed as follows: (1) the initial slopes of the FP were expressed was applied, after which there was no stimulation duringa1h as percentages of the preconditioning baseline average; and (2) washout. Stimulation was resumed for 30 min after washout. the time-matched,