Directed conversion of Alzheimer's disease patient skin fibroblasts into functional neurons.

Directed conversion of mature human cells, as from fibroblasts to neurons, is of potential clinical utility for neurological disease modeling as well as cell therapeutics. Here, we describe the efficient generation of human-induced neuronal (hiN) cells from adult skin fibroblasts of unaffected individuals and Alzheimer's patients, using virally transduced transcription regulators and extrinsic support factors. hiN cells from unaffected individuals display morphological, electrophysiological, and gene expression profiles that typify glutamatergic forebrain neurons and are competent to integrate functionally into the rodent CNS. hiN cells from familial Alzheimer disease (FAD) patients with presenilin-1 or -2 mutations exhibit altered processing and localization of amyloid precursor protein (APP) and increased production of Aß, relative to the source patient fibroblasts or hiN cells from unaffected individuals. Together, our findings demonstrate directed conversion of human fibroblasts to a neuronal phenotype and reveal cell type-selective pathology in hiN cells derived from FAD patients.

Elevated Arc/Arg 3.1 protein expression in the basolateral amygdala following auditory trace-cued fear conditioning.

The underlying neuronal mechanisms of learning and memory have been heavily explored using associative learning paradigms. Two of the more commonly employed learning paradigms have been contextual and delay fear conditioning. In fear conditioning, a subject learns to associate a neutral stimulus (conditioned stimulus; CS), such as a tone or the context of the room, with a fear provoking stimulus (unconditioned stimulus; US), such as a mild footshock. Utilizing these two paradigms, various analyses have elegantly demonstrated that the amygdala plays a role in both fear-related associative learning paradigms. However, the amygdala's involvement in trace fear conditioning, a forebrain-dependent fear associative learning paradigm that has been suggested to tap into higher cognitive processes, has not been closely investigated. Furthermore, to our knowledge, the specific amygdala nuclei involved with trace fear conditioning has not been examined. The present study used Arc expression as an activity marker to determine the amygdala's involvement in trace fear associative learning and to further explore involvement of specific amygdalar nuclei. Arc is an immediate early gene that has been shown to be associated with neuronal activation and is believed to be necessary for neuronal plasticity. Findings from the present study demonstrated that trace-conditioned mice, compared to backward-conditioned (stimulation-control), delay-conditioned and naïve mice, exhibited elevated amygdalar Arc expression in the basolateral (BLA) but not the central (CeA) or the lateral amygdala (LA). These findings are consistent with previous reports demonstrating that the amygdala plays a critical role in trace conditioning. Furthermore, these findings parallel studies demonstrating hippocampal-BLA activation following contextual fear conditioning, suggesting that trace fear conditioning and contextual fear conditioning may involve similar amygdala nuclei. Together, findings from this study demonstrate similarities in the pathway for trace and contextual fear conditioning, and further suggest possible underlying mechanisms for acquisition and consolidation of these two types of fear-related learning.

Multi-dimensional and region-specific planning for coal retirements.

Early retirement of coal-fired power is essential for remaining in line with the 2°C target set in the Paris Agreement. Plant age plays the major role in designing retirement pathways, however, this overlooks the economic and health costs associated with coal-fired power. We introduce multi-dimensional retirement schedules that account for age, operating cost, and air pollution hazards. Results show that regional retirement pathways vary substantially with different weighting schemes. Schedules based on age would retire capacity mostly in the US and EU, whereas those based on cost or air pollution would shift the majority of near-term retirements to China and India, respectively. Our approach emphasizes that a "one-size-fits-all" strategy is ineffective in addressing global phase-out pathways. It provides the opportunity for devising region-specific pathways that are sound to the local context. Our results involve emerging economies and highlight incentives for early retirement that surpass climate change mitigation and address regional priorities.

Simple and effective immobilization for radiation treatment of choroidal melanoma.

At our institution, patients diagnosed with choroidal melanoma requiring external beam radiation therapy are treated with two 6 MV volumetric-modulated arcs delivering 50 Gy over 5 daily fractions. The patient is immobilized using an Orfit head and neck mask and is directed to look at a light emitting diode (LED) during CT simulation and treatment to minimize eye movement. Patient positioning is checked with cone beam computed tomography (CBCT) daily. Translational and rotational displacements greater than 1 mm or 1° off the planned isocenter position are corrected using a Hexapod couch. The aim of this study is to verify that the mask system provides adequate immobilization and to verify our 2-mm planning target volume (PTV) margins are sufficient. Residual displacements provided by pretreatment verification and post-treatment CBCT data sets were used to assess the impact of patient mobility during treatment on the reconstructed delivered dose to the target and organs at risk. The PTV margin calculated using van Herk's method1 was used to assess patient motion plus other factors that affect treatment position, such as kV-MV isocenter coincidence. Patient position variations were small and were shown to not cause significant dose variations between the planned and reconstructed dose to the target and organs at risk. The PTV margin analysis showed patient translational motion alone required a PTV margin of 1 mm. Given other factors that affect treatment delivery accuracy, a 2-mm PTV margin was shown to be sufficient for treatment of 95% of our patients with 100% of dose delivered to the GTV. The mask immobilization with LED focus is robust and we showed a 2-mm PTV margin is adequate with this technique.

Spreading Depolarization as a Therapeutic Target in Severe Ischemic Stroke: Physiological and Pharmacological Strategies.

BACKGROUND: Spreading depolarization (SD) occurs nearly ubiquitously in malignant hemispheric stroke (MHS) and is strongly implicated in edema progression and lesion expansion. Due to this high burden of SD after infarct, it is of great interest whether SD in MHS patients can be mitigated by physiologic or pharmacologic means and whether this intervention improves clinical outcomes. Here we describe the association between physiological variables and risk of SD in MHS patients who had undergone decompressive craniectomy and present an initial case of using ketamine to target SD in MHS. METHODS: We recorded SD using subdural electrodes and time-linked with continuous physiological recordings in five subjects. We assessed physiologic variables in time bins preceding SD compared to those with no SD. RESULTS: Using multivariable logistic regression, we found that increased ETCO2 (OR 0.772, 95% CI 0.655-0.910) and DBP (OR 0.958, 95% CI 0.941-0.991) were protective against SD, while elevated temperature (OR 2.048, 95% CI 1.442-2.909) and WBC (OR 1.113, 95% CI 1.081-1.922) were associated with increased risk of SD. In a subject with recurrent SD, ketamine at a dose of 2 mg/kg/h was found to completely inhibit SD. CONCLUSION: Fluctuations in physiological variables can be associated with risk of SD after MHS. Ketamine was also found to completely inhibit SD in one subject. These data suggest that use of physiological optimization strategies and/or pharmacologic therapy could inhibit SD in MHS patients, and thereby limit edema and infarct progression. Clinical trials using individualized approaches to target this novel mechanism are warranted.

Effects of the MEK inhibitor, SL-327, on rewarding, motor- and cellular-activating effects of D-amphetamine and SKF-82958, and their augmentation by food restriction in rat.

RATIONALE: Food restriction (FR) enhances learned and unlearned behavioral responses to drugs of abuse and increases D-1 dopamine (DA) receptor-mediated activation of extracellular signal-regulated kinases (ERK) 1/2 MAP kinase in nucleus accumbens (NAc). While a role has been established for ERK signaling in drug-mediated associative learning, it is not clear whether ERK regulates unconditioned behavioral effects of abused drugs. OBJECTIVES: The purpose of this study was to determine whether blockade of ERK signaling, using the brain-penetrant MEK inhibitor, SL-327, decreases behavioral or NAc cellular responses to acute drug treatment and their augmentation by FR. MATERIALS AND METHODS: Separate experiments assessed the effects of SL-327 (50 mg/kg, intraperitoneally) on (1) the reward-potentiating effect of D-amphetamine in an intracranial self-stimulation protocol, (2) the locomotor-activating effect of the D-1 agonist, SKF-82958, and (3) Fos-immunostaining induced in the NAc by SKF-82958. RESULTS: FR rats displayed enhanced responses to drug treatment on all measures. SL-327 had no effect on sensitivity to rewarding brain stimulation or the reward-potentiating effect of D-amphetamine. The MEK inhibitor, U0126, microinjected into the NAc was also without effect. The locomotor-activating effect of SKF-82958 was unaffected by SL-327. In contrast, SL-327 decreased NAc Fos-immunostaining and abolished the difference between feeding groups. CONCLUSIONS: These results support the conclusion that ERK signaling does not mediate unlearned behavioral responses to drug treatment. However, the upregulation of ERK and downstream transcriptional responses to acute drug treatment may underlie the reported enhancement of reward-related learning in FR subjects.

Antagonizing the different stages of kappa opioid receptor activation selectively and independently attenuates acquisition and consolidation of associative memories.

Previous work from our laboratory has shown that nonspecific kappa opioid receptor (KOR) antagonism in primary somatosensory cortex (S1) can inhibit acquisition for the forebrain-dependent associative task, Whisker-Trace Eyeblink conditioning (WTEB). Although studies have demonstrated that KOR activation can alter stimuli salience, our studies controlled for these factors, demonstrating that KOR also plays a role in facilitating learning. KOR has two distinct phases of activation followed by internalization/downregulation, that each independently activate kinases and transcription factors known to mediate task acquisition and memory consolidation respectively. The current study demonstrated that antagonism of the initial phase of KOR activation in S1 via local injections of the g-protein inhibitor, pertussis toxin (PTX), blocked initial WTEB acquisition without affecting retention of the association. In contrast, KOR late phase antagonism in S1 via local injections of the GRK3-specific antagonist, guanidinonaltrindole (GNTI), blocked retention of the WTEB association without affecting task acquisition. Consistent with the known mechanism for KOR activation, KOR protein expression in S1 was found to be decreased following WTEB training, further supporting the involvement of neocortical KOR activation with learning. Prior studies have shown that task acquisition and memory consolidation are mediated by distinct molecular processes; however, little is known regarding a potential mechanism driving these processes. The current study suggests that neocortical KOR activation mediates activation of these processes with learning. This study provides the first evidence for a time- and learning-dependent property of neocortical KOR in facilitating acquisition and consolidation of associative memories, while elucidating an unexplored neocortical learning mechanism.

A Synthetic Cell-Penetrating Dominant-Negative ATF5 Peptide Exerts Anticancer Activity against a Broad Spectrum of Treatment-Resistant Cancers.

PURPOSE: Despite significant progress in cancer research, many tumor entities still have an unfavorable prognosis. Activating transcription factor 5 (ATF5) is upregulated in various malignancies and promotes apoptotic resistance. We evaluated the efficacy and mechanisms of the first described synthetic cell-penetrating inhibitor of ATF5 function, CP-d/n-ATF5-S1. EXPERIMENTAL DESIGN: Preclinical drug testing was performed in various treatment-resistant cancer cells and in vivo xenograft models. RESULTS: CP-d/n-ATF5-S1 reduced the transcript levels of several known direct ATF5 targets. It depleted endogenous ATF5 and induced apoptosis across a broad panel of treatment-refractory cancer cell lines, sparing non-neoplastic cells. CP-d/n-ATF5-S1 promoted tumor cell apoptotic susceptibility in part by reducing expression of the deubiquitinase Usp9X and led to diminished levels of antiapoptotic Bcl-2 family members Mcl-1 and Bcl-2. In line with this, CP-d/n-ATF5-S1 synergistically enhanced tumor cell apoptosis induced by the BH3-mimetic ABT263 and the death ligand TRAIL. In vivo, CP-d/n-ATF5-S1 attenuated tumor growth as a single compound in glioblastoma, melanoma, prostate cancer, and triple receptor-negative breast cancer xenograft models. Finally, the combination treatment of CP-d/n-ATF5-S1 and ABT263 significantly reduced tumor growth in vivo more efficiently than each reagent on its own. CONCLUSIONS: Our data support the idea that CP-d/n-ATF5-S1, administered as a single reagent or in combination with other drugs, holds promise as an innovative, safe, and efficient antineoplastic agent against treatment-resistant cancers. Clin Cancer Res; 22(18); 4698-711. ©2016 AACR.

Multitargeted combination effects of a triherbal formulation containing ELP against osteoporosis: in vitro evidence.

OBJECTIVES: An anti-osteoporotic herbal formula ELP containing Epimedii Herba (E), Ligustri Lucidi Fructus (L) and Psoraleae Fructus (P) was studied to investigate the herb-herb interaction (or the possible synergistic effect) among each component and to identify the principal herbs in different modes of action. METHODS: Rat osteoblast-like UMR-106 cells proliferation, rat MSCs-derived osteoblastogenesis and RANKL-induced RAW 264.7 osteoclastogenesis were adopted to investigate the bone-forming activity and bone-degrading activity of the herbal extracts. In the statistical aspect, a modified Tallarida's approach was employed to assess the synergistic effects in herbal combinations. KEY FINDINGS: Psoraleae Fructus is the active herb for stimulating osteoblast proliferation, and mild synergy was detected in the pairwise combinations EL, LP and formula ELP. In osteoblastogenesis assay, E and L are the principal herbs for promoting osteoblast differentiation and significant synergy was detected in the pairwise combination EL. For inhibiting osteoclast formation, L is the active herb and significant synergy was detected in the 3-way combination ELP. CONCLUSIONS: The presence of E, L and P is essential for ELP formula as a whole to act against osteoporosis via enhancing bone formation and reducing bone reabsorption. An optimal dosage at 150 µg/ml was proposed for ELP based on our findings.

Combined inhibition of Bcl-2/Bcl-xL and Usp9X/Bag3 overcomes apoptotic resistance in glioblastoma in vitro and in vivo.

Despite great efforts taken to advance therapeutic measures for patients with glioblastoma, the clinical prognosis remains grim. The antiapoptotic Bcl-2 family protein Mcl-1 is overexpressed in glioblastoma and represents an important resistance factor to the BH-3 mimetic ABT263. In this study, we show that combined treatment with ABT263 and GX15-070 overcomes apoptotic resistance in established glioblastoma cell lines, glioma stem-like cells and primary cultures. Moreover, this treatment regimen also proves to be advantageous in vivo. On the molecular level, GX15-070 enhanced apoptosis by posttranslational down-regulation of the deubiquitinase, Usp9X, and the chaperone Bag3, leading to a sustained depletion of Mcl-1 protein levels. Moreover, knock-down of Usp9X or Bag3 depleted endogenous Mcl-1 protein levels and in turn enhanced apoptosis induced through Bcl-2/Bcl-xL inhibition. In conclusion, combined treatment with ABT263 and GX15-070 results in a significantly enhanced anti-cancer activity in vitro as well as in vivo in the setting of glioblastoma. Both drugs, ABT263 and GX15-070 have been evaluated in clinical studies which facilitates the translational aspect of taking this combinatorial approach to the clinical setting. Furthermore we present a novel mechanism by which GX15-070 counteracts Mcl-1 expression which may lay a foundation for a novel target in cancer therapy.

Rapid adult experience-dependent anatomical plasticity in layer IV of primary somatosensory cortex.

Sensory deprivation, such as whisker deprivation, is one of the most common paradigms used to examine experience-dependent plasticity. Many of these studies conducted during development have demonstrated anatomical and synaptic neocortical plasticity with varying lengths of deprivation (for review, see Holtmaat and Svoboda, 2009). However, to date, there have been few studies exploring brief periods of experience-dependent neocortical plasticity in adulthood, similar to that observed from learning and memory paradigms (Siucinska and Kossut, 1996, 2004; Galvez et al., 2006; Chau et al., 2013). Examining both synapsin I and Golgi-Cox stained neurons in primary somatosensory cortex of unilaterally whisker-deprived adult mice, the current study demonstrates that 5 days of whisker deprivation results in more synapses in spared barrels and reduced synapses in deprived barrels. To our knowledge, this is the first study to characterize anatomical changes in layer IV of primary somatosensory cortex after a brief period of sensory deprivation in adulthood. Furthermore, findings from the present study suggest that analyses from prolonged periods of either sensory deprivation or stimulation during adulthood are missing forms of plasticity that could provide better insight into various cognitive processes, such as learning and memory.

Training-dependent associative learning induced neocortical structural plasticity: a trace eyeblink conditioning analysis.

Studies utilizing general learning and memory tasks have suggested the importance of neocortical structural plasticity for memory consolidation. However, these learning tasks typically result in learning of multiple different tasks over several days of training, making it difficult to determine the synaptic time course mediating each learning event. The current study used trace-eyeblink conditioning to determine the time course for neocortical spine modification during learning. With eyeblink conditioning, subjects are presented with a neutral, conditioned stimulus (CS) paired with a salient, unconditioned stimulus (US) to elicit an unconditioned response (UR). With multiple CS-US pairings, subjects learn to associate the CS with the US and exhibit a conditioned response (CR) when presented with the CS. Trace conditioning is when there is a stimulus free interval between the CS and the US. Utilizing trace-eyeblink conditioning with whisker stimulation as the CS (whisker-trace-eyeblink: WTEB), previous findings have shown that primary somatosensory (barrel) cortex is required for both acquisition and retention of the trace-association. Additionally, prior findings demonstrated that WTEB acquisition results in an expansion of the cytochrome oxidase whisker representation and synaptic modification in layer IV of barrel cortex. To further explore these findings and determine the time course for neocortical learning-induced spine modification, the present study utilized WTEB conditioning to examine Golgi-Cox stained neurons in layer IV of barrel cortex. Findings from this study demonstrated a training-dependent spine proliferation in layer IV of barrel cortex during trace associative learning. Furthermore, findings from this study showing that filopodia-like spines exhibited a similar pattern to the overall spine density further suggests that reorganization of synaptic contacts set the foundation for learning-induced neocortical modifications through the different neocortical layers.

PARP inhibition restores extrinsic apoptotic sensitivity in glioblastoma.

BACKGROUND: Resistance to apoptosis is a paramount issue in the treatment of Glioblastoma (GBM). We show that targeting PARP by the small molecule inhibitors, Olaparib (AZD-2281) or PJ34, reduces proliferation and lowers the apoptotic threshold of GBM cells in vitro and in vivo. METHODS: The sensitizing effects of PARP inhibition on TRAIL-mediated apoptosis and potential toxicity were analyzed using viability assays and flow cytometry in established GBM cell lines, low-passage neurospheres and astrocytes in vitro. Molecular analyses included western blots and gene silencing. In vivo, effects on tumor growth were examined in a murine subcutaneous xenograft model. RESULTS: The combination treatment of PARP inhibitors and TRAIL led to an increased cell death with activation of caspases and inhibition of formation of neurospheres when compared to single-agent treatment. Mechanistically, pharmacological PARP inhibition elicited a nuclear stress response with up-regulation of down-stream DNA-stress response proteins, e.g., CCAAT enhancer binding protein (C/EBP) homology protein (CHOP). Furthermore, Olaparib and PJ34 increased protein levels of DR5 in a concentration and time-dependent manner. In turn, siRNA-mediated suppression of DR5 mitigated the effects of TRAIL/PARP inhibitor-mediated apoptosis. In addition, suppression of PARP-1 levels enhanced TRAIL-mediated apoptosis in malignant glioma cells. Treatment of human astrocytes with the combination of TRAIL/PARP inhibitors did not cause toxicity. Finally, the combination treatment of TRAIL and PJ34 significantly reduced tumor growth in vivo when compared to treatment with each agent alone. CONCLUSIONS: PARP inhibition represents a promising avenue to overcome apoptotic resistance in GBM.

Neocortical synaptic proliferation following forebrain-dependent trace associative learning.

Many behavioral studies have suggested that learning induces neocortical synaptic modifications. However, neocortical synaptic modifications following forebrain-dependent trace associative learning has not been closely examined. Acquisition of whisker-trace-eyeblink (WTEB) conditioning, a forebrain-dependent trace associative task, has been reported to modulate the expression of cytochrome oxidase, a marker for metabolic activity, in the conditioned barrels, suggesting that trace associative conditioning induces neocortical synaptic plasticity. However, neocortical synaptic plasticity has never been directly examined following this trace associative task. To assess neocortical synaptic modifications, the present study examined synapsin I expression following WTEB conditioning. Synapsin I is part of a phosphoprotein family involved in neuronal regulation of neurotransmitter release that also exhibits an expression pattern closely correlating to synapse number. Findings from this study demonstrated that synapsin I expression is elevated in primary somatosensory neocortex in trace-paired-conditioned mice compared with unpaired-conditioned (stimulation-control) mice and naïve mice, suggesting that WTEB conditioning induces synaptic proliferation. Additional findings from the present study examining cytochrome oxidase expression replicated previous findings demonstrating that WTEB conditioning induces a learning-specific expansion of the cytochrome oxidase staining expression for conditioned barrels. Together, these results suggest that synaptic proliferation is contributing to the learning-induced metabolic augmentation previously observed in conditioned barrels following WTEB conditioning. Furthermore, these results suggest that trace associative learning facilitates neocortical synaptic modification.

Prefrontal mechanisms of behavioral flexibility, emotion regulation and value updating.

Two ideas have dominated neuropsychology concerning the orbitofrontal cortex (OFC). One holds that OFC regulates emotion and enhances behavioral flexibility through inhibitory control. The other ascribes to OFC a role in updating valuations on the basis of current motivational states. Neuroimaging, neurophysiological and clinical observations are consistent with either or both hypotheses. Although these hypotheses are compatible in principle, we present results supporting the latter view of OFC function and arguing against the former. We found that excitotoxic, fiber-sparing lesions confined to OFC in monkeys did not alter either behavioral flexibility, as measured by object reversal learning, or emotion regulation, as assessed by fear of snakes. A follow-up experiment indicated that a previously reported loss of inhibitory control resulted from damage to nearby fiber tracts and not from OFC dysfunction. Thus, OFC has a more specialized role in reward-guided behavior and emotion than has been thought, a function that includes value updating.

Amygdala's involvement in facilitating associative learning-induced plasticity: a promiscuous role for the amygdala in memory acquisition.

It is widely accepted that the amygdala plays a critical role in acquisition and consolidation of fear-related memories. Some of the more widely employed behavioral paradigms that have assisted in solidifying the amygdala's role in fear-related memories are associative learning paradigms. With most associative learning tasks, a neutral conditioned stimulus (CS) is paired with a salient unconditioned stimulus (US) that elicits an unconditioned response (UR). After multiple CS-US pairings, the subject learns that the CS predicts the onset or delivery of the US, and thus elicits a learned conditioned response (CR). Most fear-related associative paradigms have suggested that an aspect of the fear association is stored in the amygdala; however, some fear-motivated associative paradigms suggest that the amygdala is not a site of storage, but rather facilitates consolidation in other brain regions. Based upon various learning theories, one of the most likely sites for storage of long-term memories is the neocortex. In support of these theories, findings from our laboratory, and others, have demonstrated that trace-conditioning, an associative paradigm where there is a separation in time between the CS and US, induces learning-specific neocortical plasticity. The following review will discuss the amygdala's involvement, either as a site of storage or facilitating storage in other brain regions such as the neocortex, in fear- and non-fear-motivated associative paradigms. In this review, we will discuss recent findings suggesting a broader role for the amygdala in increasing the saliency of behaviorally relevant information, thus facilitating acquisition for all forms of memory, both fear- and non-fear-related. This proposed promiscuous role of the amygdala in facilitating acquisition for all memories further suggests a potential role of the amygdala in general learning disabilities.

Biomechanical-based image registration for head and neck radiation treatment.

Deformable image registration of four head and neck cancer patients has been conducted using a biomechanical-based model. Patient-specific 3D finite element models have been developed using CT and cone-beam CT image data of the planning and a radiation treatment session. The model consists of seven vertebrae (C1 to C7), mandible, larynx, left and right parotid glands, tumor and body. Different combinations of boundary conditions are applied in the model in order to find the configuration with a minimum registration error. Each vertebra in the planning session is individually aligned with its correspondence in the treatment session. Rigid alignment is used for each individual vertebra and the mandible since no deformation is expected in the bones. In addition, the effect of morphological differences in the external body between the two image sessions is investigated. The accuracy of the registration is evaluated using the tumor and both parotid glands by comparing the calculated Dice similarity index of these structures following deformation in relation to their true surface defined in the image of the second session. The registration is improved when the vertebrae and mandible are aligned in the two sessions with the highest average Dice index of 0.86 ± 0.08, 0.84 ± 0.11 and 0.89 ± 0.04 for the tumor, left and right parotid glands, respectively. The accuracy of the center of mass location of tumor and parotid glands is also improved by deformable image registration where the errors in the tumor and parotid glands decrease from 4.0 ± 1.1, 3.4 ± 1.5 and 3.8 ± 0.9 mm using rigid registration to 2.3 ± 1.0, 2.5 ± 0.8 and 2.0 ± 0.9 mm in the deformable image registration when alignment of vertebrae and mandible is conducted in addition to the surface projection of the body.

Reward-potentiating effects of D-1 dopamine receptor agonist and AMPAR GluR1 antagonist in nucleus accumbens shell and their modulation by food restriction.

RATIONALE: Previous studies have suggested that chronic food restriction (FR) increases sensitivity of a neural substrate for drug reward. The neuroanatomical site(s) of key neuroadaptations may include nucleus accumbens (NAc) where changes in D-1 dopamine (DA) receptor-mediated cell signaling and gene expression have been documented. OBJECTIVES: The purpose of the present study was to begin bridging the behavioral and tissue studies by microinjecting drugs directly into NAc medial shell and assessing behavioral effects in free-feeding and FR subjects. MATERIALS AND METHODS: Rats were implanted with microinjection cannulae in NAc medial shell and a subset were implanted with a stimulating electrode in lateral hypothalamus. Reward-potentiating effects of the D-1 DA receptor agonist, SKF-82958, AMPAR antagonist, DNXQ, and polyamine GluR1 antagonist, 1-na spermine, were assessed using the curve-shift method of self-stimulation testing. Motor-activating effects of SKF-82958 were also assessed. RESULTS: SKF-82958 (2.0 and 5.0 microg) produced greater reward-potentiating and motor-activating effects in FR than ad libitum fed (AL) rats. DNQX (1.0 microg) and 1-na spermine (1.0 and 2.5 microg) selectively decreased the x-axis intercept of rate-frequency curves in FR subjects, reflecting increased responding for previously subthreshold stimulation. CONCLUSIONS: Results suggest that FR may facilitate reward-directed behavior via multiple neuroadaptations in NAc medial shell including upregulation of D-1 DA receptor function involved in the selection and expression of goal-directed behavior, and increased GluR1-mediated activation of cells that inhibit nonreinforced responses.