[Pain measurement in cognitively impaired patients with the Doloshort scale]. / Schmerzmessung bei kognitiv beeinträchtigten Patienten mit der Doloshort-Skala.

BACKGROUND: Until recently the measurement of pain in cognitively impaired patients represented a neglected field in the diagnostics and treatment of pain. Investigations indicate a prevalence of pain in nursing home residents of between 45 % and 80 %. MATERIAL AND METHODS: This study investigated the reliability of the German translation of the Doloshort scale and compared it with the visual analog scale (VS). The aim of this study was to determine the practical applicability of this scale in the clinical routine and to calculate the intrarater reliability (retest) and interrater reliability. RESULTS: The interrater and intrarater reliability of the Doloshort scale was between 0.949 and 0.970. There was a highly significant correlation between the values of the Doloshort scale and the VAS. CONCLUSION: The Doloshort scale is a well suited measurement instrument for the evaluation of pain in cognitively impaired patients. Because of the short form only simple instructions are necessary and it has a high acceptance with users.

Serial position effects in patients with mild cognitive impairment and early and moderate Alzheimer's disease compared with healthy comparison subjects.

BACKGROUND/AIMS: This study aimed to investigate whether the serial position effects in memory can differentiate patients with different subtypes of mild cognitive impairment (MCI) from healthy controls and patients with different stages of Alzheimer's disease (AD). METHODS: The serial position effects was tested with the CERAD word list task in 184 persons (39 healthy control subjects, 15 amnestic MCI single domain subjects, 23 amnestic MCI multiple domain subjects, 31 nonamnestic MCI subjects, 45 early or mild AD patients, and 31 moderate AD patients). RESULTS: With progression of dementia, memory deficits increased and the impairment in the primacy effect during the learning trials advanced, whereas the recall of recent items was less impaired. The serial position profile of nonamnestic MCI patients resembled that of healthy control subjects, whereas amnestic MCI patients showed poorer performance in all 3 positions but no significant difference as a function of serial word position. CONCLUSION: Analyses of the serial position effect may be a useful complement to clinical neuropsychological measures for distinguishing amnestic MCI patients from normal aging and patients with different stages of dementia.

Beta-amyloid expression, release and extracellular deposition in aged rat brain slices.

Alzheimer's disease (AD) is characterized by beta-amyloid plaques, tau pathology, cholinergic cell death and inflammation. The aim of this study was to investigate whether beta-amyloid is generated, released and extracellularly deposited in organotypic brain slices. In developing slices, no amyloid-precursor protein (APP) was detectable; however, there was a strong upregulation in aging slices. In such slices, rat beta-amyloid(1-42) and -(1-40) peptides were found using four sequence-specific antibodies. APP and beta-amyloid were expressed in neurons and to a lesser extent in astrocytes. Beta-amyloid was secreted into the medium. Beta-amyloid was located extracellularly when aging slices were incubated with medium at pH 6.0 including apolipoprotein E4 (ApoE4). It is concluded that aging organotypic brain slices express beta-amyloid and that acidosis induces cell death with efflux of beta-amyloid and extracellular depositions, which is triggered by ApoE4. This novel in vitro model may enable us to investigate further the pathological cascade for AD and may be useful to explore future therapeutics.

Chromogranin peptides in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder which primarily affects motor neurons. Eight cases of ALS and seven control cases were studied with semiquantitative immunocytochemistry for chromogranin A, chromogranin B and secretogranin II that are soluble constituents of large dense core vesicles, synaptophysin as a membrane protein of small synaptic vesicles and superoxide dismutase 1. Among the chromogranin peptides, the number and staining intensity of motor neurons was highest for chromogranin A. In ALS, the staining intensity for chromogranin peptides and synaptophysin was significantly lower in the ventral horn of ALS patients due to a loss in immunoreactive motor neurons, varicose fibers and varicosities. For all chromogranins, the remaining motor neurons displayed a characteristic staining pattern consisting of an intracellular accumulation of immunoreactivity with a high staining intensity. Confocal microscopy of motor neurons revealed that superoxide dismutase 1-immunopositive intracellular aggregates also contained chromogranin A, chromogranin B and secretogranin II. These findings indicate that there is a loss of small and large dense core vesicles in presynaptic terminals. The intracellular co-occurrence of superoxide dismutase 1 and chromogranins may suggest a functional interaction between these proteins. This study should prompt further experiments to elucidate the role of chromogranins in ALS patients.

Effects of age and mild cognitive impairment on direct and indirect access to arithmetic knowledge.

The present study aimed at investigating age-related changes and mild cognitive impairment (MCI) related effects in simple arithmetic. To pursue this goal, MCI patients, healthy old adults and young adults performed three computerised tasks. The production (e.g., 3 x 4=?) and the verification task (3 x 4 12?) evaluated direct access to multiplication knowledge, the number-matching task (3 x 4 34?, 'do 3 x 4 and 34 have the same digits?') tested indirect access. In verification and number-matching, interference from related distractors (e.g., 3 x 4 followed by 16) relative to unrelated distractors (17) reflects access to stored fact representations as well as efficiency of inhibition processes. Results indicated that, compared to young adults, MCI and healthy old adults were slower in responding across tasks. In production and verification, analyses of individual latency regression slopes and intercepts suggested that these age effects were related to differences at peripheral processing stages (e.g., encoding) rather than at the central (arithmetic retrieval) stage. Differences between MCI and healthy elderly emerged only in the number-matching task. While in verification effects were comparable between groups, in number-matching MCI patients were more susceptible to interference from irrelevant information than healthy old participants. Overall, the present findings indicate that aging has a general effect on peripheral processing speed, but not on arithmetic memory retrieval. Parietal cortico-subcortical circuits mediating arithmetic fact retrieval (Dehaene, S., & Cohen, L. (1995). Towards an anatomical and functional model of number processing. Mathematical Cognition, 1, 83-120; Dehaene, S., & Cohen, L. (1997). Cerebral pathways for calculation: Double dissociation between rote verbal and quantitative knowledge of arithmetic. Cortex, 33, 219-250) thus seem to be preserved in normal aging and MCI. In contrast, MCI patients show enhanced interference in number-matching. This task-specific lack of inhibition may point to dysfunctional frontal cortico-subcortical networks in MCI.

[Differences between men and women in side effects of second-generation antipsychotics]. / Neuere Antipsychotika. Unterschiede im Nebenwirkungsprofil bei Frauen und Männern.

In this review we investigate whether sex differences exist for side effects of second-generation antipsychotics. Results are based on a MEDLINE search for the years 1974 through 2005. Even if pharmacokinetics differ between females and males, significantly higher plasma levels for women have been demonstrated only for olanzapine and clozapine. Hyperprolactinaemia is mainly induced by treatment with risperidone and amisulpride, and there is evidence for more pronounced prolactin levels in females. Most studies reviewed indicate that clozapine and olanzapine are associated with more body weight gain, once more especially in female patients. Furthermore, the few published studies indicate that metabolic syndrome is more frequent in females and there are likely no gender-specific differences between the new antipsychotic medications concerning frequency and degree of acute or chronic movement disturbance. The risk of QT prolongation with torsades de pointes arrhythmia is again higher in females. In conclusion, there is some evidence of sex differences in the side effects of second-generation antipsychotics. For better understanding of the basic mechanisms in sex differences, future studies with a primary focus on this topic are required. More specific data will help to determine how these differences shall affect clinical management.

First localization and biochemical identification of chromogranin B- and secretoneurin-like immunoreactivity in the fetal human vagal/nucleus solitary complex.

The human vagal/nucleus solitary complex is a primary visceral relay station and an integrative brain stem area which displays a high density of chromogranin B- and secretoneurin-like immunoreactivity. In this study, we localized and biochemically identified these proteins during prenatal development. At prenatal week 11, 15, 20 and 37, we performed a chromatographic analysis to identify the molecular forms of PE-11, a peptide within the chromogranin B sequence, and secretoneurin, a peptide within secretogranin II. Their localization was studied with immunocytochemistry, and was compared to that of substance P which is well established as a functional neuropeptide in the vagal/nucleus solitary complex. At prenatal week 11, chromogranin B-, secretoneurin- and substance P-like immunoreactivities were detected consisting of varicosities, varicose fibers and single cells. At the same time, PE-11 and secretoneurin appeared as a single peak in chromatographic analysis. Prohormone convertases PC1- and PC2-like immunoreactivities were also present at week 11. In general, the density for each peptide increased during later fetal stages with the highest density at week 37. These results demonstrate that each chromogranin peptide is expressed during human fetal life in neurons of the vagal/nucleus solitary complex indicating that these peptides could be important during prenatal development.

Distribution of mRNAs for Chromogranins A and B and Secretogranin II in Rat Brain.

The mRNA distribution of chromogranins A and B and secretogranin II was determined in rat brain. In Northern blots the oligonucleotide probes used hybridized with single mRNA species of the expected sizes. With tissue hybridization the mRNA signals for these three proteins were found throughout the brain. However, each of the three messages had a distinct distribution, which was exemplified by the fact that in the various regions either all three proteins, a combination of two or only one of them were apparently synthesized. Significant levels of all three mRNAs were found in several regions of the hippocampus and of the amygdala, in some thalamic nuclei and in the pyriform cortex. On the other hand the subiculum contained only the message for chromogranin A, the granule cell layer of the cerebellum only that for chromogranin B, and in posterior intralaminar thalamic and medial geniculate nuclei and in the nucleus of the solitary tract only secretogranin II mRNA was found. The distinct distributions of mRNAs for the chromogranins in various brain regions support the concept that these proteins are propeptides giving rise to functionally active components.

Distribution of neurons expressing neurokinin B in the rat brain: immunohistochemistry and in situ hybridization.

Neurokinin B (NKB) belongs to the family of neuropeptides named tachykinins. Members of this family such as substance P or neurokinin A have been proposed to function as neurotransmitters or neuromodulators. Searching for possible sites of action of NKB in the central nervous system, we have now investigated its distribution within the rat brain by immunohistochemical techniques and in situ hybridization. For immunohistology two different antisera directed against amino acid sequences within preprotachykinin B were used. One antiserum had been raised against a synthetic derivative of NKB; the other one was directed towards the amino acids 50-79 of preprotachykinin B, which are referred to as peptide 2. Essentially the same distribution of immunoreactive perikarya was obtained with both antisera and it closely corresponded to the cellular localization of preprotachykinin B mRNA. Neurons containing NKB immunoreactivity and mRNA were present in many areas including cerebral cortex, hippocampal formation, amygdaloid complex, bed nucleus of the stria terminalis, ventral pallidum, habenula, medial preoptic area, arcuate nucleus, and lateral mammillary bodies. Dense immunoreactive fibers were observed in various parts of the brain and were most prominent in the olfactory bulb and tubercle, the lateral olfactory tract, medial hypothalamus, around blood vessels of the median eminence and interpeduncular nucleus, amygdaloid nuclei, stria terminalis, subbrachial nucleus, and medial geniculate nucleus. Fibers of less intense staining were seen among other brain areas in the substantia nigra, the reticular formation, and the area of the nucleus of the solitary tract. Surgical lesion of the fasciculus retroflexus revealed that the dense fiber network observed in the interpeduncular nucleus originates from the ventral and dorsal parts of the medial habenula. Our data suggest a widespread and distinct distribution of neurons expressing NKB within the central nervous system, suggesting possible neuromodulatory roles of this neuropeptide for various brain functions.

Secretoneurin: a market in rat hippocampal pathways.

Secretoneurin is a 33-amino acid peptide, generated in brain by proteolytic processing of secretogranin II. The distribution of secretoneurin-like immunoreactivity and secretogranin II mRNA was investigated in the hippocampus of the rat. Secretogranin II mRNA was found in high concentrations throughout the granule cell and pyramidal cell layers and in many local neurons, notably in the hilus of the dentate gyrus. The general distributional pattern of secretoneurin-like immunoreactivity was characterized by a prominent staining in the area of the terminal field of mossy fibers with an obvious staining in the infrapyramidal area of CA3 and a strongly immunopositive band in the inner third of the molecular layer of the dentate gyrus. Lesions of the granule cells by local injection of colchicine significantly reduced secretoneurin-like immunoreactivity in the terminal field of mossy fibers, but not in the inner molecular layer of the dentate gyrus. On the other hand, destruction of interneurons of the dentate gyrus (mossy cells and certain gamma-aminobutyricacid-ergic interneurons) by kainic acid-induced seizures was associated with a reduction of secretoneurin-like immunoreactivity in the inner molecular layer of the dentate gyrus. However, 30 days after kainic acid-induced seizures, a strongly secretoneurin-immunoreactive band reappeared in this area, which at this late time point is due to sprouting of mossy fibers collaterals. Our experiments suggest a widespread distribution of secretoneurin-like immunoreactivity in neurons of the hippocampal formation with a preferential localization in excitatory pathways including associational/commissural fibers originating from secretoneurin-containing mossy cells.

Distribution of secretoneurin immunoreactivity in the spinal cord and lower brainstem in comparison with that of substance P and calcitonin gene-related peptide.

Secretoneurin is a peptide of 33 amino acids generated in brain by proteolytic processing of secretogranin II. The distribution of this newly characterized peptide was investigated by means of immunocytochemistry and in situ hybridization in the spinal cord and lower brainstem of the rat. The staining pattern of secretoneurin immunoreactivity (IR) was compared to that of substance P (SP) and calcitonin gene-related peptide (CGRP) in adjacent sections. A high density of secretoneurin-IR fibers and terminals was found in lamina I and outer lamina II of the caudal trigeminal nucleus and of the spinal cord at all levels, around the central canal, and in the sympathetic and parasympathetic areas of the lateral cell columns. The ventral horn displayed a low to moderate density of secretoneurin-IR. The highest number of secretogranin II mRNA-containing cells was found in lamina II of the dorsal horn and in neurons of the dorsal root ganglia. In the white matter, secretoneurin-IR was most prominent in the dorsolateral part of the lateral funiculus and in the tract of Lissauer. The distributions of secretoneurin-IR and SP-IR were strikingly similar. CGRP-IR and secretoneurin-IR overlapped in the outer laminae of the dorsal horn, in the lateral cell column, and probably in some motoneurons. This study establishes that, like SP and CGRP, secretoneurin is a peptide highly concentrated in the terminal field of primary afferents and in sympathetic and parasympathetic areas. Thus secretoneurin might be involved in the modulation of afferent transmission.

Evidence for a high density of secretoneurin-like immunoreactivity in the extended amygdala of the rat.

Secretoneurin is a novel 33-amino-acid neuropeptide produced by endoproteolytic processing from secretogranin II, which is a member of the chromogranin/secretogranin family. In this immunocytochemical study, we compared the distribution pattern of secretoneurin immunoreactivity with that of tyrosine hydroxylase, calbindin, substance P, and Leu-enkephalin in adjacent sections of rat forebrain. Secretoneurin appeared mainly in varicosities and fibers. Only a few cell bodies were stained. In the nucleus accumbens, a partial overlap of secretoneurin-immunoreactive patches with enkephalin-immunopositive areas was found. Secretoneurin displayed low to moderate levels of immunoreaction in calbindin-rich as well as in calbindin-immunonegative areas of the caudate-putamen. In the globus pallidus, entopeduncular nucleus, and substantia nigra, secretoneurin immunoreactivity was oriented ventromedially preferentially in woolly fibers. The dense immunostaining in the medial nucleus accumbens was directly continuous with dense secretoneurin immunoreactivity in the bed nucleus of the stria terminalis. Two strongly secretoneurin-immunopositive bands, one in the sublenticular portion and a smaller one along the posterior limb of the anterior commissure, interconnected the highly secretoneurin-immunopositive centromedial amygdala with the bed nucleus of the stria terminalis. Thus, the distribution pattern of secretoneurin immunoreactivity provides a marker of the extended amygdala that forms a continuum between the centromedial amygdala and the bed nucleus of the stria terminalis.

Further evidence that behavioral tests and neuropeptide mRNA and tissue level alterations can differentiate between typical and atypical antipsychotic drugs.

This study was designed to compare some behavioral and biochemical effects of chronic treatment with a range of antipsychotic drugs. Gene expression of enkephalin, chromogranin A, chromogranin B, and secretogranin II and their respective peptide products were studied with in situ hybridization and radioimmunoassays after daily oral administration of haloperidol, clozapine, risperidone, or zotepine for 21 days. In behavioral tests, significant catalepsy was induced by haloperidol only. All four antipsychotic drugs increased hind paw retraction time but only haloperidol also increased forelimb retraction time. In the caudate putamen, haloperidol increased both enkephalin mRNA expression and enkephalin tissue levels. Neither of these parameters was altered by the other three drugs. In the prefrontal cortex, antipsychotic drugs generated a distinct pattern of gene expression in two regards. First, the dopamine D(2) receptor antagonist, haloperidol, did not significantly alter synaptic protein levels or their encoding mRNAs. Secondly, there was a differential change in tissue levels and mRNA expression since secretogranin II was not affected by any tested antipsychotic drug. This study shows that different types of antipsychotic drug induce distinct behavioural effects as well as differential changes in the biosynthesis of synaptic proteins and their encoding mRNAs. The data reinforce the notion that haloperidol can be classed as a typical antipsychotic drug whilst clozapine, zotepine, and risperidone reflect their atypical classification.

Concomitant increase of somatostatin, neuropeptide Y and glutamate decarboxylase in the frontal cortex of rats with decreased seizure threshold.

The neuropeptides somatostatin and neuropeptide Y and the activity of glutamate decarboxylase were determined in the frontal cortex of rats subjected to experimental epilepsy. Two different animal models, (1) rats kindled for 4 weeks by daily injection of pentylenetetrazole, and (2) rats which had undergone strong limbic seizures induced by kainic acid, were used. Decreased seizure threshold, as shown by injection of a subconvulsive dose of pentylenetetrazole, was observed 10 days after the last kindling session and 1 month after injection of kainic acid, respectively. Significantly increased levels of somatostatin (by 60%), neuropeptide Y (135%) and increased activity of glutamate decarboxylase (22%) were found in the frontal cortex of rats previously treated with kainic acid. Separation of somatostatin-like immunoreactivity by size exclusion high-performance liquid chromatography showed a marked increase of immunoreactivity in fractions containing the somatostatin precursor (by 200%) and less prominently of somatostatin-14 and somatostatin-28 (by 60 and 80%, respectively). Michaelis-Menten kinetics of glutamate decarboxylase revealed an increased maximal velocity (Vmax) in the frontal cortex of kainic acid-treated rats, but no change in the Km value was found. Similar results were also obtained in pentylenetetrazole-kindled rats. Injection of cysteamine (100 mg/kg, i.p.) resulting in a 30% decrease of cortical somatostatin in kainic acid-pretreated rats markedly suppressed seizures induced by an otherwise subconvulsive dose of pentylenetetrazole.(ABSTRACT TRUNCATED AT 250 WORDS)

Nerve growth factor and glial cell line-derived neurotrophic factor restore the cholinergic neuronal phenotype in organotypic brain slices of the basal nucleus of Meynert.

Loss of cholinergic neurons is found in the medial septum and nucleus basalis of Meynert in Alzheimer's disease. Recent observations suggest that cholinergic neurons down-regulate their phenotype and that growth factors may rescue cholinergic neurons. The aim of this study was to investigate whether cholinergic neurons of the basal nucleus of Meynert can be cultured in rat organotypic slices, and if nerve growth factor and glial cell line-derived neurotrophic factor can rescue the cholinergic phenotype. In the organotypic slices, glial cells, GABAergic and cholinergic neurons were visualized using immunohistochemistry. The number of cholinergic neurons was found to be very low in slices cultured without exogenous nerve growth factor. Analysis of nerve growth factor tissue levels by enzyme-linked immunosorbent assay revealed very low endogenous tissue levels. When slices were incubated with 100ng/ml nerve growth factor during the initial phase of culturing, a stable expression of choline acetyltransferase was found for up to several weeks. After eight weeks in culture with nerve growth factor or two to three weeks after nerve growth factor withdrawal, numbers of detected cholinergic neurons decreased. Neurons incubated with nerve growth factor displayed a significantly enlarged cell soma compared to neurons without growth factors. In cultures incubated for up to nine weeks, it was also found that glial cell line-derived neurotrophic factor was capable of restoring the cholinergic phenotype. The low-affinity p75 and high-affinity trkA receptors, as well as the glial cell line-derived neurotrophic factor receptor GFRalpha-1, could be visualized in slices using immunohistochemistry. In conclusion, it is shown that, in the axotomized organotypic slice model, the number of cholinergic neurons is decreased, but can be partly restored by nerve growth factor and glial cell line-derived neurotrophic factor.

Differential changes in tachykinins after kainic acid-induced seizures in the rat.

Changes in concentrations of the tachykinins substance P, neurokinin A and neurokinin B were investigated in rat brains after kainic acid-induced seizures. Two different antisera, one detecting substance P specifically and one recognizing neurokinins A and B but not substance P, were used. Subsequently to the acute seizures (3 h after kainic acid) significant decreases (by 25-40%) in total neurokinin (A + B) and substance P immunoreactivities were observed in the frontal cortex, dorsal hippocampus and striatum. Depending on the brain area neurokinin immunoreactivity recovered 1-3 days after injection of the toxin and was significantly increased in the frontal cortex (by 40-60%) and the hippocampus (by 100-300%) after 10-60 days. Further analysis by high pressure liquid chromatography revealed that increases in both neurokinin A and neurokinin B concentrations contributed to the increases in total neurokinin immunoreactivity 30 days after kainic acid. At the same time significantly increased levels were also observed for substance P in the frontal cortex (by 30%). Furthermore, increases were also observed in the concentrations of neuropeptide K and gamma-preprotachykinin-A(72-92) in the frontal cortex and the hippocampus 30 days after the kainic acid treatment.

Comparative distribution of neurokinin B-, substance P- and enkephalin-like immunoreactivities and neurokinin B messenger RNA in the basal forebrain of the rat: evidence for neurochemical compartmentation.

The distribution of neurokinin B was investigated in the basal forebrain of the rat by immunocytochemistry with an antibody directed against neurokinin B, and with a second antiserum directed to a peptide sequence contained within its precursor, and by means of in situ hybridization. The staining pattern was compared in closely adjacent sections to that of substance P- and enkephalin-like immunoreactivities. Cholecystokinin immunoreactivity was used to delineate the apparent dorsolateral border of the ventral pallidum with the nucleus accumbens. Remarkable similarities are found in the distribution of these peptides in the basal forebrain, especially in its ventral part. The coarse band-like terminal staining pattern (woolly fibers) that has been shown by others for substance P- and enkephalin-like immunoreactivity, is also observed for neurokinin B-like immunoreactivity, mainly in the ventral pallidum. Medium-sized cells are found arranged in clusters or singularly within the caudate-putamen even without colchicine. A band of strong neurokinin B immunoreactivity extends just underneath the dorsal pallidum to the amygdala. In comparison to enkephalin the most distinct observation is that neurokinin B immunoreactivity is not present in the dorsal pallidum (global pallidus). Neurokinin B immunoreactivity was not found in the pars reticulata of the substantia nigra which is strongly immunopositive for substance P. The number of cells detected by in situ hybridization was higher compared to the immunopositive perikarya throughout the basal ganglia. The staining pattern observed reflects a partial overlap with the substance P and enkephalin system although a differential distribution for each of these peptides was observed for cell bodies and axons terminals.

Localization of neuroendocrine secretory protein 55 messenger RNA in the rat brain.

Neuroendocrine secretory protein 55 (NESP55) is a recently characterized secretory protein localized to large dense-core vesicles resembling the class of chromogranins. We investigated the distribution of the messenger RNA encoding for NESP55 in the rat brain by in situ hybridization with specific 35S-labelled oligonucleotides. NESP55 messenger RNA was detected only on neuronal but not glial cells. In the brain, expression of NESP55 messenger RNA was most prominent in several areas throughout the midbrain and brainstem, including the locus coeruleus, the raphe complex and the reticular formation. NESP55 messenger RNA-expressing cells were also found in many areas and nuclei throughout the hypothalamus. Neocortical areas, the hippocampus and the cerebellum were devoid of NESP55 messenger RNA-containing neurons. From this distribution pattern, a significant overlap of NESP55 expression with the noradrenergic, adrenergic and serotonergic transmitter systems was evident. The present study defines, for the first time, the cellular localizaton of NESP55 messenger RNA in the rat brain. The present results provide the basis for future studies defining the as yet obscure function of NESP55.

Limbic seizures cause pronounced changes in the expression of neurokinin B in the hippocampus of the rat.

Immunohistological and in situ hybridization techniques were used to study the influence of kainic acid-induced seizures and of pentylenetetrazol kindling on neurokinin B immunoreactivity and neurokinin B mRNA in the rat hippocampus. Pronounced increases in neurokinin B immunoreactivity were observed in the terminal field of mossy fibres 10-60 days after intraperitoneal injection of kainic acid. These slow but persistent increases in immunoreactivity were accompanied by markedly enhanced expression of neurokinin B mRNA in the granule cells and in hilar interneurons adjacent to the granule cell layer. These changes were preceded by transient increases in neurokinin B mRNA and immunoreactivity in CA1 pyramidal cell layer two and 10 days after kainic acid, which, however, subsided later on. Pentylenetetrazol kindling caused similar increases in neurokinin B mRNA expression in granule cells and in CA1 pyramidal cells, but not in hilar interneurons. In CA1, increased neurokinin B message was present two days after termination of the kindling procedure but not after 10 days. Sixty days after kainic acid injection, neurokinin B immunoreactivity extended to the inner-third of the molecular layer of the dentate gyrus. After pentylenetetrazol kindling, a neurokinin B-immunoreactive band was observed in the infrapyramidal region of CA3. Lesions of the dentate granule cells by local injection of colchicine in kainic acid-treated rats abolished the supragranular neurokinin B-positive staining, whereas it was almost unchanged after transection of the ventral hippocampal commissure. These observations suggest that neurokinin B immunoreactivity may be located in ipsilateral mossy fibres undergoing collateral sprouting to the inner molecular layer or to the infrapyramidal region in CA3, respectively. Preprotachykinin A mRNA, which encodes for neurokinin A and substance P, and substance P immunoreactivity were not changed in the hippocampus of epileptic rats compared with untreated animals. The observed changes in neurokinin B immunoreactivity and mRNA indicate that specific functional and morphological changes may be induced in hippocampal neurons by recurrent limbic seizures.

Functional changes in neuropeptide Y- and somatostatin-containing neurons induced by limbic seizures in the rat.

The influence of sustained epileptic seizures evoked by intraperitoneal injection of kainic acid on the gene expression of the neuropeptides somatostatin and neuropeptide Y and on the damage of neurons containing these peptides was studied in the rat brain. Injection of kainic acid induced an extensive loss of somatostatin and, though less pronounced, of neuropeptide Y neurons in the inner part of the hilus of the dentate gyrus. Neuropeptide Y-immunoreactive neurons located in the subgranular layer of the hilus, presumably pyramidal-shaped basket cells, were spared by the treatment. Although neuropeptide Y messenger RNA was not detected in granule cells of control rats, it was found there after kainic acid seizures at all time intervals investigated (12 h to 90 days after injection of kainic acid). High concentrations of neuropeptide Y messenger RNA were especially observed 24 h after injection of kainic acid. At this time neuropeptide Y messenger RNA was also transiently observed in CA1 pyramidal cells. Neuropeptide Y synthesis in granule cells in turn gave rise to an intense immunoreactivity of the peptide in the terminal field of mossy fibers which persisted for the entire time period (90 days) investigated. In addition, neuropeptide Y messenger RNA concentrations were also drastically elevated in presumptive basket cells located at the inner surface of the granule cell layer, especially at the "late" time intervals investigated (30-90 days after kainic acid). These data support the concept that extensive activation of granule cells by limbic seizures contributes to the observed neuronal cell death in CA3 pyramidal neurons and interneurons of the hilus. Consecutively, basket cells containing neuropeptide Y and presumably GABA might be activated and participate in recurrent inhibition of granule cells. Neuropeptide Y-immunoreactive fibers observed in the inner molecular layer at "late" time intervals after kainic acid may result either from collateral sprouting of mossy fibers or from basket cells extensively expressing the peptide. It is speculated that neuropeptide Y synthesized and released at a high rate from granule cells and basket cells may exert a protective action against seizures.