Electroencephalographic,behavioral, and histopathologic features of seizures induced by intra-amygdala application of folic acid in cats

The effects of intracerebral injection of folic acid are still controversial. We studied the electroencephalographic, behavioral, and histopathologic consequences of the seizures induced by intra-amygdala administration of various doses of FA in freely moving cats. The severity of the seizures was dose-dependant. For doses of 25 and 50 nmol, single low-amplitude spikes appeared in the amygdala 15 to 20 min after injection and a typical amygdala symptomatology was observed. From doses of 100 nmol recurrent limbic seizures occurred 40 to 80 min after injection. Finally, from doses of 150 nmol secondarily generalized seizures were induced, which could be followed by death 4 to 6 h after injection. The severity of the cerebral lesions was related to both the dose and the paroxysmal manifestations. In cases with short survival time (6 h) and few seizures the pathology was restricted to a lymphocytic and glial reaction with some ischemic cells at the injected site. In cases with status epilepticus, edema and neuronal degeneration was observed in the hippocampus, amygdala, thalamic nuclei of the midline, entorhinal cortex, and cerebellum. No neuronal alteration at the injected site was observed. For longer survival times (8 days) edema was less severe, but hyperchromatic cells were still numerous. These results, compared with those of intra-amygdala administration of kainic acid, suggest that pathologic lesions induced in cats by folic acid more closely resemble those described in man after some status epilepticus.     

Neurotoxic amino acid lesions of the lateral hypothalamus: a parametric comparison of the effects of ibotenate, N-methyl-d,l-aspartate and quisqualate in the rat

Separate groups of rats received unilateral lesions of the lateral hypothalamus by one of the 3 amino-acid neurotoxins, ibotenic acid (IBO), N-methyl-D,L-aspartic acid (NMA) or quisqualic acid (QA). A parametric comparison was made between the toxins on the extent of neuronal cell loss and the specificity of damage, by a systematic variation of both the volume (0.25-1.0 mm3) and concentration (0.03-0.12 M) injected. Neurotoxic potency on hypothalamic neurones varied in the order IBO greater than NMA greater than QA. All 3 toxins spared magnocellular supraoptic and accessory nuclei as well as medial hypothalamic neurones. Extrahypothalamic damage differed between the toxins: ventral thalamic neurones were susceptible to NMA and QA but only slightly to IBO, whereas the medial amygdala was sensitive to IBO but not NMA or QA. All 3 toxins spared ascending monoamine systems passing through the lateral hypothalamus, as assessed by biochemical assays of forebrain dopamine and serotonin. However, IBO induced a bilateral increase in dopamine levels, which was interpreted as an indirect consequence of the loss of lateral hypothalamic efferents projecting to the midbrain.     

Smoking, gender, and dietary influences on erythrocyte essential fatty acid composition among patients with schizophrenia or schizoaffective disorder.

BACKGROUND: Prior reports of decreased levels of essential fatty acids among schizophrenic patients have generated several hypotheses proposing inherent abnormalities in phospholipid and fatty acid metabolism and have provided the basis for treatment trials; however, these essential fatty acid aberrations may be attributable to uncontrolled factors, such as smoking, rather than abnormalities inherent to schizophrenia. METHODS: Erythrocyte fatty acid compositions were quantified in 72 medicated schizophrenic or schizoaffective patients both at baseline and after 16 weeks of supplementation with 3 g/day of either ethyl-eicosapentaenoic acid or placebo. Current smoking status, gender, dietary survey, and Montgomery Asburg Depression Rating Scale, Repeatable Battery for the Assessment of Neuropsychological Status, Abnormal Involuntary Movement Scale, and Positive and Negative Syndrome Scale scores were assessed. RESULTS: Schizophrenic patients who smoked had lower baseline erythrocyte docosahexaenoic acid percent (2.98 +/-.7 vs. 3.59 +/- 1.2, p <.005) and eicosapentaenoic acid (EPA) percent (.39 +/-.13 vs. 47 +/-.22, p <.05), compared with nonsmokers, with a significant gender interaction (p <.01) in multivariate analyses of variance. Baseline arachidonic acid did not differ. Smokers reported lower dietary intake (percent total fat) of linolenic acid (F = 10.1, p <.003) compared with nonsmokers. Nonsmoking women reported greater dietary intake of EPA compared with smoking men or nonsmokers of either gender. CONCLUSIONS: Smoking status, gender, and dietary intake significantly predicted erythrocyte polyunsaturated fatty acid status among schizophrenic patients. No evidence was found for subgroups of schizophrenia or relationships to specific symptom severity on the basis of erythrocyte fatty acids. Prior reports of abnormalities of essential fatty acid metabolism among schizophrenic patients may have been an artifact of patients' smoking behavior and differences in dietary intake of omega-3 fatty acids.     

Effects of valproic acid,carbamazepine, and phenobarbitone on the fatty acid composition of erythrocyte membranes in children

PURPOSE: To investigate a possible relation between antiepileptic drugs (AEDs) and the fatty acid composition of membranes. METHODS: Fatty acid (FA) composition of erythrocytes was studied in children with epilepsy receiving AED monotherapy. Children taking valproate (VPA, n = 28), carbamazepine (CBZ, n = 17), or phenobarbitone (PB, n = 14) were compared with healthy controls (n = 25). FAs were measured by capillary-gas chromatography (GC-FID). RESULTS: Significant changes (p < 0.05) in the FA composition of membranes were found. In children treated with VPA, C13:0 was decreased (8.2 +/- 2% vs. 10.7 +/- 4% in controls) and C14:0 increased (1.4 +/- 0.5% vs.1 +/- 0.5% in controls). C17:0 again was reduced (9.9 +/- 4% vs. 13.2 +/- 6% in controls), whereas the long-chained acids were enhanced: C18:2n-6 (6 +/- 2.4% vs. 3.9 +/- 2.5% in controls), and C20:4n-6 (1.9 +/- 1.7% vs. 1.4 +/- 0.5% in controls). The nonidentified FAs also increased with VPA therapy: 2.5 +/- 0.8% versus 1.7 +/- 0.9% in controls. Children treated with CBZ showed only minimal changes of FA composition: C13:0 was decreased compared with controls (8 +/- 2% vs. 10.7 +/- 4%). No changes were seen in patients taking PB. The mean corpuscular volume (MCV) showed important differences between the study groups: MCV was 84.7 +/- 6.0 fl during VPA therapy (p < 0.001) and 85.7 +/- 4.1 fl with CBZ (p < 0.001). During PB, the MCV increased to 82.87 +/- 3.29 fl compared with controls (78.73 +/- 4.92 fl; p < 0.01). CONCLUSIONS: VPA therapy is associated with changes of the FA composition of membranes, which is not the case with PB therapy. The implications of this finding remain to be established.     

咖啡酸、罗非考昔及两者连用对喹啉酸诱导的大鼠行为变化及谷胱甘肽氧化还原紊乱的改善与修复作用

目的环氧和酶（COX）抑制剂和脂肪氧化酶（LOX）抑制剂已被证实具有神经保护作用,但对其具体机制目前研究甚少。喹啉酸具有兴奋毒性作用,通过激活NMDA受体,引起类似于亨廷顿舞蹈症（Huntington’s Disease,HD）的症状,包括行为、形态以及生化水平上的各种异常。本研究旨在探讨咖啡酸（LOX特异性抑制剂）和罗非考昔（COX特异性抑制剂）各自以及两者连用对喹啉酸引起的大鼠神经毒性的改善和修复作用。方法在大鼠右侧纹状体内注射喹啉酸,诱导神经毒性。随后每天给大鼠口服咖啡酸或罗非考昔,或两者同时服用。用一系列行为学及生化检测方法检测咖啡酸和罗非考昔,以及两者连用对喹啉酸诱导的大鼠行为变化及谷胱甘肽氧化还原紊乱的改善和修复作用。结果在纹状体注射喹啉酸不仅能降低大鼠体重,引起运动失调,而且能破坏纹状体内氧化还原间的平衡,表现为谷胱甘肽水平降低,以及氧化谷胱甘肽水平升高。长期服用咖啡酸或罗非考昔,以及两者连用都能显著减轻喹啉酸引起的行为变化,修复氧化还原水平的平衡。而当剂量为2.5mg/kg时,咖啡酸未表现出任何保护作用。结论本实验结果表明,大脑的兴奋性中毒有可能通过改变谷胱甘肽的水平影响氧化与抗氧化间的平衡。环氧合酶和脂肪氧化酶通路都可能参与了喹啉酸诱导的神经毒性过程。这些结果为治疗HD提供了研究靶点。     

Effects of caffeic acid, rofecoxib, and their combination against quinolinic acid-induced behavioral alterations and disruption in glutathione redox status

Objective

The neuroprotective roles of cyclooxygenase (COX) and lipooxygenase (LOX) inhibitors have been well documented. Quinolinic acid (QA) is a well-known excitotoxic agent that could induce behavioral, morphological and biochemical alterations similar with symptoms of Huntington’s disease (HD), by stimulating NMDA receptors. However, the exact roles of COX and LOX inhibitors in HD have not yet been explained. The present study aims to elucidate the effects of caffeic acid (a specific inhibitor for LOX), rofecoxib (a specific inhibitor for COX-2), and their combination in ameliorating QAinduced neurotoxicity in rats.

Methods

QA was injected into the right striatum of rats to induce neurotoxicity. Caffeic acid and rofecoxib were then orally administered separately. In the combination study, caffeic acid and rofecoxib were administered together. After that, a series of behavioral assessments were conducted to determine the effects of caffeic acid and rofecoxib, respectively, and the co-effect of caffeic acid and rofecoxib, against QA-induced neurotoxicity.

Results

Intrastriatal QA administration (300 nmol) not only induced a significant reduction in body weight and motor incoordination, but also altered the redox status (decreased glutathione and increased oxidized glutathione level) in striatum, as compared to the sham group. Moreover, chronic treatment with caffeic acid (5 mg/kg and 10 mg/kg, respectively, p.o.) or rofecoxib (10 mg/kg, p.o.) could significantly attenuate QA-induced behavioral alterations and restore the redox status in striatum. However, at the dose of 2.5 mg/kg, caffeic acid did not show any significant effects on these parameters in QA-treated rats. Furthermore, the combination of rofecoxib (10 mg/kg) and caffeic acid (5 mg/kg) could significantly protect against QA neurotoxicity.

Conclusion

The in vivo study indicates that excitotoxic injury to the brain might affect oxidant/antioxidant equilibrium by eliciting changes in glutathione. Moreover, the LOX and the COX pathways may be both involved in quinolinic-induced neurotoxicity, which provides a promising target for HD treatment.     

Long-term decreases in striatal dopamine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid after a single injection of amphetamine in iprindole-treated rats: Time course and time-dependent interactions with amfonelic acid

The administration of a single dose of (+)-amphetamine sulfate (9.2 mg/kg) to rats treated with iprindole hydrochloride (10 mg/kg) produced marked decreases in the striatal concentrations of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) one week after drug administration. Significant changes were not observed in striatal 5-hydroxyindoleacetic acid (5-HIAA) nor in norepinephrine, DA, DOPAC, HVA, and 5-HIAA concentrations in frontal cortex and a limbic forebrain sample containing primarily nucleus accumbens and olfactory tubercles. In time-course experiments, decreases in striatal DA were apparent by 12 h after amphetamine plus iprindole administration and persisted for at least 4 weeks. Decreases in striatal DOPAC and HVA followed a similar time course, except decreases in these parameters were observed at 6 h as well. The administration of amfonelic acid, a potent DA uptake inhibitor, up to 8 h but not at 12 h after amphetamine administration prevented the decreases in striatal DA, DOPAC and HVA at one week after the administration of the drug to iprindole-treated rats. These data indicate that the actions of amphetamine which are necessary and sufficient for the production of long-term decreases in striatal DA, DOPAC and HVA are dependent upon the integrity of the neuronal uptake mechanism for DA and occur within 12 h after the administration of amphetamine to iprindole-treated rats. Although amfonelic acid prevented the long-term effects of amphetamine on striatal DA neurons, it did not alter the decrease in DOPAC produced by amphetamine at 6 h after the administration of amphetamine plus iprindole. This finding suggests that the ability of amfonelic acid to prevent the long-term effects of amphetamine on striatal DA neurons in iprindole-treated rats is not due to a blockade of the entry of amphetamine into the neuron and, thus, suggests that the access of amphetamine to the inside of the neuron is not sufficient for the production of its long-term, possibly neurotoxic, effects on striatal DA neurons.     

Distribution of norepinephrine, epinephrine, dopamine, serotonin, 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindole-3-acetic acid in dog brain

The distribution and endogenous concentrations of norepinephrine, epinephrine, dopamine, serotonin, 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindole-3-acetic acid were determined in the brains of adult dogs. Norepinephrine and epinephrine were localized primarily in 'central core' areas in brain stem and hypothalamus. Dopamine (DA) and its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acids (HVA), were localized primarily in basal ganglia with relatively high concentrations also found in amygdala, septum and substantia nigra. HVA was also found in relatively high concentrations in areas where DA concentrations was very low. Serotonin and 5-hydroxyindole-3-acetic acid levels were highest in brain stem, hypothalamus, globus pallidus and nucleus accumbens. Epinephrine levels were higher than in previously studied species, at times as much as 25-30% of norepinephrine and frequently greater than dopamine in brain stem and hypothalamus. Using the ratios 5-hydroxyindole-3-acetic acid/serotonin and homovanillic acid/dopamine as indicators of serotonin and dopamine turnover and utilization, both putative transmitters were found to be generally more highly utilized in areas of lower concentration, especially in brain stem and cortex. Catecholamines were found to be unconjugated in dog brain. DOPAC and HVA were found to exist primarily in the unconjugated form. DOPAC was found to be slightly conjugated in most areas while 10-20% of HVA was present in the conjugated form in most cases.     

Neurophysiologic effects of folate compounds in hippocampus, in vitro

Pteroylglutamic acid (PGA, folic acid) and related compounds were studied for their electropysiologic effects on guinea pig hippocampal slices in vitro. Folates are found to have marked neuroexcitatory actions in CA3 and lesser but substantial excitatory effects in CA1. The dentate gyrus is minimally activated by folates. Extracellular recordings in CA3 reveal augmentation in single unit activity, evoked responses, and at 50–100 μM PGA concentrations, spontaneous epileptiform discharges are generated. Progressive increase in PGA concentrations to at least 2 mM do not result in loss of this activity. At concentrations of 200 μM, epileptiform bursts in CA3, precede those in CA1 which are lost by sectioning the Schaeffer collateral pathway. However, with 500 μM PGA, spontaneous bursts occur in CA1 isolated from CA3. The change induced by PGA primarily affects the population spike resulting in lower stimulus threshold and higher amplitude response.Measurement of threshold concentration necessary to produce spontaneous epileptiform activity of folate related compounds reveals the following order of potency: pteroylglutamic acid (PGA) ≥ formyl tetrahydrofolic acid (folinic acid) > > methyltetrahydrofolate (MTHF) ≥ methotrexate (MTX) ≥ glutamic acid. Pteroic acid, pterin,N(p-aminobenzoyl)L-glutamic acid are inactive. Methotrexate does not diminish the response to PGA. Thus, the entire folate molecule is needed for full activity. Folates represent naturally occurring, highly epileptogenic compounds whose mechanism of action is not dependent on metabolic products. Possibly they act at a central receptor as a neuromodulator.     

Ruminiclostridium 5, Parabacteroides distasonis,and bile acid profile are modulated by prebiotic diet and associate with facilitated sleep/clock realignment after chronic disruption of rhythms

Chronic disruption of rhythms (CDR) impacts sleep and can result in circadian misalignment of physiological systems which, in turn, is associated with increased disease risk. Exposure to repeated or severe stressors also disturbs sleep and diurnal rhythms. Prebiotic nutrients produce favorable changes in gut microbial ecology, the gut metabolome, and reduce several negative impacts of acute severe stressor exposure, including disturbed sleep, core body temperature rhythmicity, and gut microbial dysbiosis. In light of previous compelling evidence that prebiotic diet broadly reduces negative impacts of acute, severe stressors, we hypothesize that prebiotic diet will also effectively mitigate the negative impacts of chronic disruption of circadian rhythms on physiology and sleep/wake behavior. Male, Sprague Dawley rats were fed diets enriched in prebiotic substrates or calorically matched control chow. After 5 weeks on diet, rats were exposed to CDR (12 h light/dark reversal, weekly for 8 weeks) or remained on undisturbed normal light/dark cycles (NLD). Sleep EEG, core body temperature, and locomotor activity were recorded via biotelemetry in freely moving rats. Fecal samples were collected on experimental days –33, 0 (day of onset of CDR), and 42. Taxonomic identification and relative abundances of gut microbes were measured in fecal samples using 16S rRNA gene sequencing and shotgun metagenomics. Fecal primary, bacterially modified secondary, and conjugated bile acids were measured using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Prebiotic diet produced rapid and stable increases in the relative abundances of Parabacteroides distasonis and Ruminiclostridium 5. Shotgun metagenomics analyses confirmed reliable increases in relative abundances of Parabacteroides distasonis and Clostridium leptum, a member of the Ruminiclostridium genus. Prebiotic diet also modified fecal bile acid profiles; and based on correlational and step-wise regression analyses, Parabacteroides distasonis and Ruminiclostridium 5 were positively associated with each other and negatively associated with secondary and conjugated bile acids. Prebiotic diet, but not CDR, impacted beta diversity. Measures of alpha diversity evenness were decreased by CDR and prebiotic diet prevented that effect. Rats exposed to CDR while eating prebiotic, compared to control diet, more quickly realigned NREM sleep and core body temperature (ClockLab) diurnal rhythms to the altered light/dark cycle. Finally, both cholic acid and Ruminiclostridium 5 prior to CDR were associated with time to realign CBT rhythms to the new light/dark cycle after CDR; whereas both Ruminiclostridium 5 and taurocholic acid prior to CDR were associated with NREM sleep recovery after CDR. These results support our hypothesis and suggest that ingestion of prebiotic substrates is an effective strategy to increase the relative abundance of health promoting microbes, alter the fecal bile acid profile, and facilitate the recovery and realignment of sleep and diurnal rhythms after circadian disruption.     

Ethanol,baclofen, and kainic acid neurotoxicity

The neurotoxicity induced by intrastriatal injections of kainic acid was greater in rats drinking approximately 4 ml ethanol per day for 16 days before injection than in controls. Intraperitoneal injection of 5 mg/kg baclofen (parachlorophenyl GABA), 30 min before the kainic acid injections had a slight protective action. These results have implications in connection with reported effects of ethanol and baclofen on glutamate systems in the brain.     

Amine metabolites, neuroendocrine findings, and personality dimensions as correlates of suicidal behavior

Levels of 5-hydroxyindoleactic acid (5-HIAA) and homovanillic acid (HVA) were measured in the cerebrospinal fluid (CSF) of 62 female inpatients with major depression (n = 19), schizophrenic disorder (n = 18), alcohol dependence (n = 13), and other disorders (n = 12). Nineteen patients had attempted suicide immediately before admission, and six had used violent methods. Fifty-three patients received a dexamethasone suppression test (DST) following lumbar puncture and all completed the Marke-Nyman Temperament Scale (Hungarian version) within 10 days. CSF 5-HIAA was significantly lower in patients who had made violent suicide attempts, but did not differ between suicide attempters who had taken drug overdoses and nonattempters. CSF HVA showed no significant differences. Dexamethasone nonsuppression occurred more frequently among attempters, but this difference did not reach statistical significance. Among the three personality dimensions of the Marke-Nyman Scale, validity was lower and stability higher in suicidal patients; both findings were more pronounced in the violent subgroup. CSF 5-HIAA and Marke-Nyman validity were inversely correlated to each other in all three subgroups, and violent attempters could be separated from the other two groups by their simultaneously low CSF 5-HIAA values and Marke-Nyman validity scores.     

Black-gold: a simple, high-resolution histochemical label for normal and pathological myelin in brain tissue sections

A novel haloaurophosphate complex called Black-Gold has been synthesized and applied to localize myelin within the central nervous system. The technique is tailored to studies using formalin fixed non-solvent processed tissue. The technique stains large myelinated tracts dark red-brown, while the individual myelinated axons appear black. This study demonstrates how this novel tracer can be used to localize both normal and pathological myelin. Specific myelin changes associated with exposure to diverse neurotoxicants including kainic acid, domoic acid, 3-nitropropionic acid, Fluoro-Gold and isoniazid are demonstrated and characterized. This study also demonstrates how Black-Gold can be combined with other histochemical markers including Nissl stains, retrogradely transported fluorescent tracers and fluorescent markers of neuronal degeneration. Advantages associated with the Black-Gold technique include high resolution, high contrast, short histochemical processing time, and consistent reproducibility.     

Reduction of cortical dopamine, noradrenaline, serotonin and their metabolites in Parkinson''s disease

Transport processes operating in astrocytes were examined by measuring unidirectional fluxes of 42K and 36Cl in primary cultures of mouse astrocytes, at steady-state with respect to ion composition. The total K+ uptake rate was 2025 nmol X mg-1 protein X min-1. This rate was not influenced by furosemide (2 mM), an inhibitor of Cl- uptake and K+-K+ exchange, or acetazolamide (0.1 mM), a carbonic anhydrase inhibitor. Ouabain (1 mM) inhibited the uptake rate by 541 nmol X mg-1 X min-1. The equilibrated K+ content was determined to be 696 nmol X mg-1. The rate constant for efflux was 2.76 min-1. This equals an efflux rate of 1921 nmol X mg-1 X min-1, i.e. a similar value as the influx. Furosemide and ouabain did not inhibit the efflux. The equilibrated Cl- content was found to be 167 nmol X mg-1 and it decreased in furosemide-treated cells to 68.1 nmol X mg-1. The total Cl- uptake was 35 nmol X mg-1 X min-1 and it was inhibited by furosemide or bumetanide by 27 nmol X mg-1 X min-1. The mean resting membrane potential was found to be -77.4 mV. From these data we conclude: (1) that the K+ uptake rates are high, as can be expected from estimates based on literature data for K+ conductance in mammalian glial cells in situ; and (2) that the cells possess a very low relative Cl- permeability.     

Neuroendocrine,epigenetic, and intergenerational effects of general anesthetics

The progress of modern medicine would be impossible without the use of general anesthetics (GAs). Despite advancements in refining anesthesia approaches, the effects of GAs are not fully reversible upon GA withdrawal. Neurocognitive deficiencies attributed to GA exposure may persist in neonates or endure for weeks to years in the elderly. Human studies on the mechanisms of the long-term adverse effects of GAs are needed to improve the safety of general anesthesia but they are hampered not only by ethical limitations specific to human research, but also by a lack of specific biological markers that can be used in human studies to safely and objectively study such effects. The latter can primarily be attributed to an insufficient understanding of the full range of the biological effects induced by GAs and the molecular mechanisms mediating such effects even in rodents, which are far more extensively studied than any other species. Our most recent experimental findings in rodents suggest that GAs may adversely affect many more people than is currently anticipated. Specifically, we have shown that anesthesia with the commonly used GA sevoflurane induces in exposed animals not only neuroendocrine abnormalities (somatic effects), but also epigenetic reprogramming of germ cells (germ cell effects). The latter may pass the neurobehavioral effects of parental sevoflurane exposure to the offspring, who may be affected even at levels of anesthesia that are not harmful to the exposed parents. The large number of patients who require general anesthesia, the even larger number of their future unexposed offspring whose health may be affected, and a growing number of neurodevelopmental disorders of unknown etiology underscore the translational importance of investigating the intergenerational effects of GAs. In this mini review, we discuss emerging experimental findings on neuroendocrine, epigenetic, and intergenerational effects of GAs.     

Neurotoxic effects of endogenous materials: quinolinic acid, L-pyroglutamic acid, and thyroid releasing hormone (TRH)

The previously reported, dose-related, and selective neurotoxic action of 100 to 200 nmol quinolinic acid on intrastriatal injection was confirmed. A slight neurotoxicity was obtained with 250 nmol thyroid releasing hormone but not with a similar dose of L-pyroglutamic acid.     

A possible effect of the methylxanthines caffeine,theophylline and aminophylline on postnatal myelination of the rat brain

In order to determine whether an amino acid may act as a neurotransmitter in the perforant pathway we examined the effect of lesion of rat entorhinal cortex on the concentrations of various amino acids in the hippocampus proper and fascia dentata. Only the aspartic acid content was found significantly decreased after the lesion. This decreases is not due to a loss from target cells of the perforant pathway, but rather to a loss from its degenerating terminals.