Transient expression of c-fos during the development of the rat cerebral cortex

The present study has explored with immunocytochemical methods the expression of the proto-oncogene c-fos during the pre- and postnatal development of the cerebral cortex of the rat. The immunostaining of the Fos protein follows a strikingly precise spatiotemporal pattern: it occurs uniquely within layer VIb of the developing cerebral cortex, and is transient, lasting only from embryonic day 20 until postnatal day 1. The expression of c-fos in layer VIb may be related to the dynamic changes that occur at this level during development.     

Non-competitive NMDA antagonists and anti-oxidant drugs reduce striatal atrophy and facilitate recovery of function following lesions of the rat cortex

Following brain injury there is an excessive release of glutamate, a reduction in levels of cellular Mg+ +, and the generation of oxygen free radicals. These processes may contribute to the severity of the behavioral impairments seen following brain injury by leading to secondary neuronal degeneration. The present experiment investigates the relative effects of three drugs (MK-801, an NMDA antagonist; magnesium chloride, an NMDA antagonist; and N-tert-butyl-α-phenylnitrone (PBN), an anti-oxidant and free radical scavenger) which disrupt different aspects of the pathophysiological process, in reducing these impairments. Direct comparisons of these drugs may determine if one treatment is more effective than another, or if one is detrimental. In addition, the effects of combination treatments including PBN and MK-801 or MgCl2 were examined. These combination treatment were aimed at the possibility of potentiating the beneficial effects observed after administration of these agents alone. Rats received unilateral electrolytic lesions of the somatic sensorimotor cortex followed by a regimen of MK-801 (1 mg/kg), MgCl2 (1 mmol/kg), PBN (100 mg/kg), MK-801 + PBN (1 mg/kg, 100 mg/kg), MgCl2 + PBN (1 mmol/kg, 100 mg/kg), or saline (1 ml/kg) beginning 15 min following injury. Rats were tested on several sensorimotor tasks (i.e. forelimb placing and foot-fault) for 43 days following the cortical lesions. Rats receiving any of the single or combination drug treatments showed a significant facilitation of recovery on the sensorimotor tasks compared to saline control rats. On one behavioral test (i.e. foot-fault) there was a significant further enhancement of the recovery by combination treatments compared to the single treatment groups. These data are consistent with the idea that excessive release of glutamate, reduction in Mg+ + levels, and free radical generation contribute to the severity of the behavioral impairments following cortical injury, and that arresting these processes results in a facilitation of behavioral recovery. Anatomical analysis showed that all drug treatments decreased the amount of atrophy seen in the ipsilateral striatum.     

NMDA antagonists and clonidine block c-fos expression during morphine withdrawal

The c-fos gene is expressed in the central nervous system (CNS) in response to neuronal stimuli. Induction of c-fos in certain CNS regions occurs following naltrexone precipitated withdrawal in morphine dependent rats. Non-competitive (MK801) and competitive (LY274614) NMDA receptor antagonists and clonidine, an alpha₂ partial agonist, attenuate the intensity of naltrexone precipitated withdrawal. We determined the levels of c-fos mRNA by solution hybridization in several brain regions in control and morphine dependent rats following pretreatment with saline, MK801 (1 mg/kg, s.c.), LY274614 (100 mg/kg, i.p.), or clonidine (1.5 mg/kg, i.p.). Morphine treatment increased c-fos mRNA levels in striatum (STR) and amygdala (AMY). Naltrexone did not alter c-fos mRNA levels in placebo-treated rats. However, naltrexone increased c-fos mRNA levels in morphine dependent rats in the nucleus accumbens (NA), frontal cortex (FC), AMY, and hippocampus (HIP) but not in STR or spinal cord. Pretreatment with MK801 blocked this effect of naltrexone in AMY but not in NA, FC, or HIP, while pretreatment with LY274614 or clonidine blocked this effect of naltrexone in AMY and NA but not in FC or HIP. These results further delineate both the neuroanatomical pathways involved in morphine withdrawal and the locus of action of compounds that reduce morphine-withdrawal symptoms. © 1995 Wiley-Liss, Inc.     

NMDA receptor expression in the mouse cerebellar cortex

A detailed, light microscopic study on the distribution of the N-methyl-D-aspartate receptor subunit 1(NMDAR1) was carried out with immunohistochemistry and in situ hybridization on the cerebellar cortex of the mouse. With a monoclonal antibody, labeling of Purkinje cell bodies varied from intense to negative, while heavy dendritic staining was limited to the proximal dendrites (unlike the rat, which also had heavily stained distal dendrites). In the granular layer, the cell bodies and the dendritic shafts of Golgi II cells were only moderately stained, but very intense labeling was associated with granule cell bodies, and with their dendrites and dendritic endings in the glomeruli. The mossy and climbing fibers were negative. In situ hybridization with a cRNA probe showed levels and spatial distributions of NMDAR1 mRNA consistent with the immunolabeling pattern, in that signals were strongest in the granular and Purkinje cell layers and relatively low or absent in the molecular layer and white matter. The findings are consistent with the hypothesis that NMDAR1 may be especially well concentrated at the synaptic target sites of the mossy and climbing fibers. In the mouse, NMDAR1 at the parallel fiber sites associated with Purkinje cell spiny branchlets may differ from the rat in its level of expression or in its molecular configuration. © 1995 Wiley-Liss, Inc.     

Lesion-induced changes in NMDA receptor subunit mRNA expression in rat visual cortex

Focal lesions in the visual cortex are well known to induce pronounced perilesional reorganization of the neuronal circuitry. Since NMDA receptors crucially control synaptic plasticity and reorganization, we studied lesion-induced changes in their subunit expression and biophysical properties. Between 8 and 10 days after focal thermolesioning, pyramidal neurones in the near surround of the lesion were studied in acute brain slices. We found a significant decrease in the ratio of NR2A and NR2B subunit mRNA as compared to neurones from sham operated animals. Interestingly, no significant differences in the properties of NMDA receptor-mediated postsynaptic currents (NMDA PSCs) were observed between lesioned and sham operated animals. Thus, the observed perilesional changes in the NR2A/NR2B mRNA ratio appear to be subthreshold to result in significant changes in the functional properties of NMDA receptors.     

Genetic and epigenetic regulation of NMDA receptor expression in the rat visual cortex

The susceptibility of cortical networks to use-dependent modifications declines with age (critical period) and this decline of neuronal plasticity during development is paralleled by the shortening of NMDA receptor EPSCs. We showed previously in the somatosensory cortex that the shortening of NMDA receptor kinetics correlates with a developmentally-regulated increase in the NR2A subunit expression. Here we examine whether this developmental regulation of NR2A expression is related to the duration of critical periods and whether it is influenced by experience. Functional NMDA receptors and their molecular characteristics are studied in identified layer IV neurons of rat visual cortex. In this structure the time course of the critical period differs from that in the somatosensory cortex and can be changed by sensory deprivation, thus permitting examination of correlations between the time course of receptor expression and the duration of the critical period. We find that the developmental expression of the NR2A subunit is delayed compared with the somatosensory cortex, in agreement with the prolonged critical period in the visual cortex. Moreover, sensory deprivation further delays the developmental change in the NMDA receptor subunit composition, demonstrating the activity dependence of this process and strengthening the correlation between changes in subunit composition and the time course of the critical period.     

Chronic ethanol exposure and withdrawal influence NMDA receptor subunit and splice variant mRNA expression in the rat cerebral cortex

Chronic ethanol exposure and subsequent withdrawal are known to change NMDA receptor activity. This study examined the effects of chronic ethanol administration and withdrawal on the expression of several NMDA receptor subunit and splice variant mRNAs in the rat cerebral cortex. Ethanol dependence was induced by ethanol vapour exposure. To delineate between seizure-induced changes in expression during withdrawal and those due to withdrawal per se, another group of naive rats was treated with pentylenetetrazol (PTZ) injection (30 mg/kg, i.p.). RNA samples from the cortices of chronically treated and withdrawing animals were compared to those from pair-fed controls. Changes in NMDA receptor mRNA expression were determined using ribonuclease protection assays targetting the NR2A, -2B, -2C and NR1-pan subunits as well as the three alternatively spliced NR1 inserts (NR1-pan describes all the known NR1 splice variants generated from the 5' insert and the two 3' inserts). The ratio of NR1 mRNA incorporating the 5' insert vs. that lacking it was decreased during ethanol exposure and up to 48 h after withdrawal. NR2B mRNA expression was elevated during exposure, but returned to control levels 18 h after withdrawal. Levels of NR2A, NR2C, NR1-pan and both 3' NR1 insert mRNAs from the ethanol-treated groups did not alter compared with the pair-fed control group. No changes in the level of any NMDA receptor subunit mRNA was detected in the PTZ-treated animals. These data support the hypothesis that changes in NMDA receptor subunit composition may underlie a neuronal adaptation to the chronic ethanol-inhibition and may therefore be important in the precipitation of withdrawal hyperactivity.     

Non-competitive antagonists of N-methyl-D-aspartate prevent spontaneous neuronal death in primary cultures of embryonic rat cortex

Primary cultures of embryonic rat cerebral cortex were treated after 17 days in vitro for 10 min with a single dose of the non-competitive antagonists of N-methyl-D-aspartate (NMDA) receptor MK 801, TCP, and GK 11. They were then maintained in vitro for 31, 59, or 73 days, and then processed for the immunocytochemical detection of neuron-specific enolase (NSE). Immunoreactive cells were counted in treated and control cultures, and it was found that, except at 31 days, treated cultures contained far more NSE immunoreactive cells than controls. Moreover, this effect was dose-dependent, since with both TCP and GK 11 neuron survival was significantly higher with, respectively, 20 microM and 5 microM than with the lowest concentration of 2.5 microM. We tentatively conclude that spontaneous neuron death occurring in primary cultures in vitro is at least partly related to the NMDA-associated Ca++ channel, since the common property of the molecules we used is to block this channel. The relevance of this mechanism of cell death in vitro to neuronal death in vivo is discussed.     

大鼠听皮质NMDA受体亚单位NR2BmRNA年龄-依赖性表达

应用原位杂交技术,研究了大鼠生后发育过程中,听皮质神经元NMDA受体亚单位NR2B mRNA年龄-依赖性的表达变化.特异性DIG标记寡核苷酸探针检测显示,NR2B亚单位mRNA阳性神经元数量从出生后即有高水平表达,之后,随着天龄增长逐渐递减,在出生后14 d出现一过性表达高峰,14～21 d时表达水平急剧降低(＞50.0%),21 d后保持低水平表达至成年.研究结果为进一步在皮质水平上探讨出生后听觉功能发育可塑性的分子机制提供了重要资料.     

大鼠听皮质NMDA受体亚单位NR2BmRNA年龄-依赖性表达

应用原位杂交技术 ,研究了大鼠生后发育过程中 ,听皮质神经元NMDA受体亚单位NR2BmRNA年龄 依赖性的表达变化。特异性DIG标记寡核苷酸探针检测显示 ,NR2B亚单位mRNA阳性神经元数量从出生后即有高水平表达 ,之后 ,随着天龄增长逐渐递减 ,在出生后 14d出现一过性表达高峰 ,14～ 2 1d时表达水平急剧降低(>5 0 .0 % ) ,2 1d后保持低水平表达至成年。研究结果为进一步在皮质水平上探讨出生后听觉功能发育可塑性的分子机制提供了重要资料     

Ontogeny of AMPA and NMDA receptor gene expression in the developing sheep white matter and cerebral cortex

This study examined the hypothesis that the high prevalence of white matter injury in premature infants is associated with increased expression of calcium-permeable forms of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype of glutamate receptors in pre-myelinating white matter. We characterized expression of subunits of the AMPA, and for reference, the N-methyl-d-aspartate (NMDA), glutamate receptors at 0.5, 0.65, 0.85, and term gestation in the ovine fetal white matter and cerebral cortex. There was a low expression of the critical calcium-impermeable AMPA receptor GluR2 subunit in subcortical white matter both absolutely and relative to other AMPA subunits throughout gestation. In contrast, GluR2 subunit mRNA expression fell in the cerebral cortex with increasing gestation whereas protein expression increased. These findings suggest a vulnerability of subcortical white matter to AMPA receptor-mediated calcium toxicity throughout the second half of gestation. Thus, the hypothesis that AMPA receptor-mediated glutamate toxicity contributes to brain damage in premature infants needs to be revised.     

Evaluation of glycine site antagonists of the NMDA receptor in global cerebral ischaemia

In the present studies we have investigated the effects of a range of glycine site antagonists of the N-methyl--aspartate (NMDA) receptor in the gerbil model of global cerebral ischaemia. The compounds tested were (+)-3-amino-1-hydroxy-2-pyrrolidone (HA 966, 15 mg/kg), 7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2(H)-quinolinone) (L-701,324, 40 mg/kg), 7-chloro-3-(cyclopropylcarbonyl)-4-hydroxy-2(1H)-quinolinone) (L-701,252, 50 mg/kg), (3-(3-hydroxyphenyl)prop-2-ynyl 7-chloro-4 hydroxy-2(1H)-quinolone-3-carboxylate) (L-701,273, 50 mg/kg), 5-nitro-6,7-dichloro-2,3-quinoxalinedione (ACEA 1021, 25 mg/kg) and [(E)-3[(phenylcarbamoyl) ethenyl]-4,6-dichloroindole-2-carboxylic acid sodium salt (GV 150526A, 40 mg/kg). All compounds were administered via the i.p. route 30 min before and again at 2 h 30 min after 5 min bilateral carotid artery occlusion (BCAO) in the gerbil. For comparison we also evaluated a non-competitive NMDA antagonist, (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801, 2 mg/kg) and an α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) antagonist, (3S,4aR, 6R, 8aR)-6-[2-(1(2)H-tetrazole-5-yl)]decahydroisoquinoline-3-carboxylic acid (LY293558, 20 mg/kg). In the present studies L-701,252, L-701,324 and L-701,273 provided a small degree of neuroprotection. ACEA 1021, GV 150526A and HA 966 failed to provide any neuroprotection, while MK-801 provided significant (20%) protection. In contrast LY293558 provided good (55%) neuroprotection. These results indicate that glycine site antagonists and competitive NMDA antagonists provide a small degree of neuroprotection in global cerebral ischaemia. In contrast, AMPA receptor antagonists provide more robust neuroprotection in global cerebral ischaemia.     

Evaluation of glycine site antagonists of the NMDA receptor in global cerebral ischaemia

The central neurochemical and neuroendocrine effects of a psychogenic (ferret exposure) and a neurogenic (restraint) stressor were assessed in rats that had been selectively bred for differences in amygdala excitability manifested by either Fast or Slow amygdala kindling epileptogenesis. While these rat lines differ in their emotionality, their behavioral styles were dependent on the nature of the stressor to which they were exposed. During restraint, the Slow rats were mostly immobile, while Fast rats persistently struggled. In contrast, Fast rats were more immobile in response to the ferret. Yet, the more emotional Slow rats exhibited a greater corticosterone response to the ferret, while comparable corticosterone responses between lines were evident following restraint. Although both stressors influenced norepinephrine (NE), dopamine (DA) and/or serotonin (5-HT) activity in brain regions typically associated with stressors (e.g., locus coeruleus, paraventricular nucleus of the hypothalamus, nucleus accumbens, prefrontal cortex), considerable amine alterations were evident in the medial and basolateral amygdala nuclei, but not in the central nucleus. Moreover, greater NE changes were apparent in the medial amygdala of the left hemisphere. Similarly, DA alterations also were greater in the left medial amygdala in response to stressors. Despite very different behavioral styles, however, the two lines often exhibited similar amine alterations in response to both stressors.     

Olfactory bulbectomy alters NMDA receptor levels in the rat prefrontal cortex

Olfactory bulbectomized (OBX) rats show a variety of behavioral and biochemical deficits that parallel human depression. We investigated the expression of glutamate receptor subtypes in cortical and subcortical brain regions following bilateral olfactory bulbectomy in adult rats. Quantitative receptor autoradiography using [(125)I]MK-801 (NMDA receptor), [(3)H]AMPA (AMPA receptor), and [(3)H]kainate (kainate receptor) was performed on brain sections at 1-5 weeks following olfactory bulbectomy. Our results show an elevation of NMDA receptors in the medial prefrontal cortex within 1 week following bulbectomy, which persisted up to at least 5 weeks post-bulbectomy. Neither kainate nor AMPA receptors were altered in any brain region examined. The potential significance of these results is discussed in light of experimental findings supporting a role for NMDA receptors in the mechanism of action of antidepressant drugs and the pathophysiology of major depression.     

Opiate receptor localization in rat cerebral cortex

The differential distributions of [3H]naloxone-labeled and [3H]D-Ala-D-Leu-enkephalin-labeled opiate receptors in rat cerebral cortex were localized autoradiographically and quantified by grain counting and computerized densitometry. In addition, receptor distributions were compared to terminal patterns of thalamocortical projections labeled by axoplasmic transport of [3H]amino acids. Opiate receptors labeled with [3H]naloxone in a mu ligand selectivity pattern show striking laminar heterogeneity and are densest in limbic cortical areas, intermediate in the motor cortex, and fewest in the primary sensory areas. By contrast, opiate receptors labeled with [3H]D-Ala2-D-Leu5-enkephalin in a delta ligand selectivity pattern are much more homogeneously distributed across both regions and laminae within regions. Mu receptors in most cortical areas have density peaks in layers I and VI and each peak shows a density gradient that is sloped within the layer so that the highest densities are at the most superficial and the deepest portions of cortex. In addition, there is an intermediate peak whose laminar position varies depending on the area in which it is found. In rostral agranular cortex, including limbic and motor areas, the [3H]naloxone binding peaks are in layers I, III, and VI. In primary somatosensory cortex, the intermediate peak is in layer Va and in most of remaining homotypical cortex it is in layer IV. Some areas have only bilaminar labeling, in superficial and deep layers; these include portions of the sulcal and retrosplenial cortices. Piriform and entorhinal cortices have dense [3H]naloxone binding only in the deepest layer and show a descending gradient of density toward the superficial layer. The positions of the mu receptor peaks were compared with termination patterns of projections originating in the thalamus. Close correspondence was found between receptor binding in the prelimbic, primary somatosensory, and entorhinal areas and projection terminations arising from the thalamic mediodorsal, posterior, and central medial nuclei, respectively. Although regional variations in [3H]D-Ala2-D-Leu5-enkephalin-labeled receptor density are uncommon, a gradual decrease in the number of sites along the dorsomedial wall of the cortex from anterior cingulate to caudal retrosplenial limbic cortex can be observed. Laminar variations in binding density are small as well; higher concentrations of the peptide binding sites are usually found in the deep cortical layers. These findings emphasize aspects of opiate receptor architecture which may be relevant to identifying cortical "opiatergic" neurocircuitry and raise the possibility of opiate modulation of thalamocortical transmission.     

Glutamate, NMDA and NMDA receptor antagonists: cardiovascular effects of intrathecal administration in the rat

Selected excitatory amino acids and antagonists were tested for their effects on arterial pressure and heart rate when administered intrathecally at the second (T2) or ninth (T9) thoracic spinal levels in urethane-anesthetized Sprague-Dawley rats with spontaneous or artificial respiration. Intrathecal administration of glutamate (1 mumol) and N-methyl-D-aspartic acid (NMDA; 2 nmol) at T9 increased arterial pressure and heart rate. The response began within 1 min, peaked at 2-3 min and persisted for 8-15 min. The maximum changes were 20-25 mm Hg for arterial pressure and 40-50 beats/min for heart rate. These responses were prevented by systemic administration of hexamethonium (10 mg/kg). Responses to administration of NMDA at the two spinal levels were essentially the same. Effects elicited by NMDA but not by glutamate were blocked by pretreatment with the NMDA receptor antagonists, D,L-2-amino-5-phosphonovaleric acid (APV; 10 nmol, intrathecal administration) and ketamine (7 mg/kg, i.v.). Intrathecal administration of APV (10, 50 and 200 nmol) at T2 produced dose-dependent decreases in arterial pressure without changing heart rate. The results support the hypothesis that NMDA receptors are involved in regulation of sympathetic output at the spinal level. They also indicate that in this preparation there is a tonic activation of NMDA receptors in sympathetic pathways to the vessels but not to the heart. Finally, the persistence of the response to glutamate in the presence of NMDA receptor antagonists suggests the involvement of non-NMDA receptors in spinal control of sympathetic output.     

PSA-NCAM expression in the piriform cortex of the adult rat. Modulation by NMDA receptor antagonist administration

Uptake of biocytin and biotin was investigated in cultured transformed variants of neuronal (NB2a neuroblastoma) and glial (C6 astrocytoma) CNS cells. NB2a cells took up both compounds but biocytin was transported more efficiently than biotin in the nanomolar concentration range. In NB2a cells a single transport mechanism was found for biocytin with different kinetic parameters in the presence of high extracellular Na+ (Km 0.4 microM, Vmax 20 pmol/min/mg), K+ (Km 1.7 microM, Vmax 32 pmol/min/mg), or choline+ (Km 0.1 microM, Vmax 5 pmol/min/mg). Two transport systems (Km1 17 microM, Vmax1 53 pmol/min/mg; Km2 314 microM, Vmax2 360 pmol/min/mg) were identified for biotin with only system 1 being Na+-dependent. Biocytin uptake was competitively inhibited by excess biotin but not vice versa. Inhibition studies with structural analogs indicated different specificities for biotin and biocytin uptake. Biocytin uptake into C6 cells was hardly detectable whereas biotin was taken up by diffusion (kD 0.6 microl/min/mg) and a single saturable mechanism (Km 70 microM, Vmax 119 pmol/min/mg) at high extracellular Na+. High extracellular K+ enhanced biotin diffusion into C6 cells. Inhibition studies with structural analogs revealed a less specific biotin uptake mechanism in C6 than in NB2a cells. Biocytin normalized deficient biotin-dependent propionyl-CoA carboxylase activity within 4 h in biotin-deficient NB2a cells whereas in C6 cells reactivation was <20% thereby confirming that biocytin is only poorly transported into C6 cells. Specific biocytin uptake into NB2a cells is to our knowledge the first demonstration of a carrier-mediated transport mechanism for this compound. Neuronal biocytin uptake might contribute to the pathogenesis of biotinidase deficiency where biocytin is present in elevated levels.     

神经元移行异常的大鼠脑皮层中NMDA的表达

目的 观察神经元移行异常(neurona1 migration disorders,NMDs)动物模型脑组织的病理变化以及N-甲基-D-天门冬氨酸受体(n-methyl-d-aspartate receptor,NMDA)的表达.方法 三组Sprague-Dawley孕鼠分别在孕15天,孕17天以及孕19天接受2.25Gy的X射线照射约5分钟,其后代成年后即为NMDs动物模型.观察指标为:存活率、脑组织的病理变化以及皮层中NMDA的表达.结果 胚胎期较早接受射线的大鼠,存活率低,大脑皮层结构紊乱严重,皮层NRl和NR2A的表达高.结论 在NMDs的大鼠脑皮层中,NRl和NR2A表达增加,且其表达增加的程度能反映NMDs的严重程度.NMDA的上调可能是NMDs患者致痫的主要病因.     

Early auditory deprivation alters expression of NMDA receptor subunit NR1 mRNA in the rat auditory cortex

The expression of NMDA receptor NR1 subunit mRNA was studied in rat auditory cortex (AC) on different postnatal days using digoxigenin-labeled oligonucleotide probes. The results showed that NR1 expression increased from birth to postnatal day 35 (P35) and remained constant until P56. The most significant increases occurred between P7 and P14. Changes in NR1 mRNA expression in rats subjected to monaural hearing deprivation on P7, P21, P35, and P49 were examined on P56. Between P7 and P21, when the rat auditory system was still in a critical period of development, NR1 mRNA expression was lower in the contralateral AC, which received auditory signals from the plugged ear, than in the ipsilateral AC. However, no significant difference was observed between the rats deprived of hearing on P35 and those deprived of hearing on P42, the end of the critical period of auditory development. These results showed that monaural hearing deprivation during early postnatal development was associated with decreased NR1 mRNA expression in the contralateral AC and suggested the involvement of NR1 in auditory function during development. They also indicated that, during postnatal development, environmental factors changed the functional plasticity of neurons in the AC through NR1 receptor expression. Taken together, these findings provide a possible underlying mechanism for the development of postnatal auditory function.     

The AMPA receptor potentiator LY404187 increases cerebral glucose utilization and c-fos expression in the rat.

AMPA receptor potentiators enhance AMPA receptor-mediated glutamatergic neurotransmission and may have therapeutic potential as cognitive enhancers or antidepressants. The anatomical basis for the action of AMPA receptor potentiators is unknown. The aim of this study was to determine the effects of the biarylpropylsulfonamide AMPA receptor potentiator, LY404187 (0.05 to 5 mg/kg subcutaneously), upon cerebral glucose utilization and c-fos expression using 14C-2-deoxglucose autoradiography and c-fos immunocytochemistry. LY404187 (0.5 mg/kg) produced significant elevations in glucose utilization in 28 of the 52 anatomical regions analyzed, which included rostral neocortical areas and the hippocampus, as well the dorsal raphe nucleus, lateral habenula, and locus coeruleus. No significant decreases in glucose utilization were observed in any region after LY404187 administration. The increases in glucose utilization with LY404187 (0.5 mg/kg) were blocked by pretreatment with the AMPA receptor antagonist LY293558 (25 mg/kg), indicating that LY404187 acts through AMPA receptor-mediated mechanisms. LY404187 (0.5 mg/kg) also produced increases in c-fos immunoreactivity in the cortex, locus coeruleus, and the dorsal raphe nucleus. These studies demonstrate neuronal activation in key brain areas that are associated with memory processes and thus provide an anatomical basis for the cognitive enhancing effects of AMPA receptor potentiators.