Infrared Spectrophotometry Studies on Cerebral Tumor s-RNAs

Deuterated s-RNAs prepared from a medulloblastoma, a glioblastoma and a frontal lobe show a different relative intensity in the 1680 cm–1 band. The phenomenon can be related to the frequency in the base pairings; it may depend either on a proportionally different content of t-RNAs and/or on qualitative variations in the primary and secondary structure of the polynucleotides. Irrespective of the kind of variation and its causes, the finding once more proves the existence of chemical differences between neuroectodermal tumors, with an undifferentiated and those with an atypical cellular component.

Neuropeptides in CSF and post-mortem brain tissue of normal controls, schizophrenics and Huntington's choreics

Studies describing the CNS distribution of neuropeptides can provide important new insights concerning their possible physiological functions. The rational for studying human post-mortem tissue, as well as some methodological constraints, are reviewed. The localization of NT in normal human brain is presented. Concentrations of NT, TRH, and SRIF were determined in brain tissue from normal controls and patients with schizophrenia or Huntington's chorea. Specific alterations in the levels of these neuropeptides were found in each disease. Appreciable quantities of NT immunoreactivity are present in human CSF. Sub-normal CSF-NT levels were found in a sub-group of unmedicated schizophrenics but were elevated back to normal concentrations following neuroleptic treatment. Although the pathophysiological significance of these findings is unclear, they nevertheless indicate that neuropeptides are important brain constituents which deserve further study.

Reserpine-induced decrease in type I and II corticosteroid receptors in neuronal and lymphoid tissues of adrenalectomized rats

The effect of the biogenic amine depleting drug, reserpine, on the concentration of type II corticosteroid receptors (i.e., glucocorticoid receptors) in neuronal (hippocampus, frontal cortex, hypothalamus), lymphoid (circulating lymphocytes, spleen, thymus) and pituitary tissues as well as hippocampal type I (i.e., mineralocorticoid) receptors was examined in adrenal-intact and adrenalectomized (ADX) rats. Reserpine (2 mg/kg) or vehicle was administered to adrenal-intact rats for 2 consecutive days. Following the second injection rats were ADX and sacrificed 24 h later. Reserpine significantly decreased type I and II hippocampal receptors as well as type II receptors in frontal cortex, hypothalamus, lymphocytes and spleen. Since the reserpine-induced decreases in receptor content could be due to reserpine-induced elevations in circulating corticosterone levels, reserpine (2 mg/kg) or vehicle was administered to 1-day ADX rats which were then sacrificed 2 days later (i.e., 3 days post ADX). A 1-day ADX control group was also included. The 3-day ADX regimen produced significant or nearly significant increases in type II receptors in hippocampus, frontal cortex, hypothalamus, lymphocytes and spleen in vehicle-treated rats. Reserpine attenuated the ADX-induced upregulation of type II receptors in hippocampus, frontal cortex, lymphocytes and spleen, but had no effect on the ADX-induced upregulation of type II receptors in the hypothalamus. The ADX-induced increase in hippocampal type I receptors was not affected by reserpine treatment. In a final experiment, reserpine (2 mg/kg) or vehicle was administered immediately after ADX and rats were sacrificed 24 h later in order to assess the effect of reserpine on basal (i.e., nonupregulated) corticosteroid receptor levels in the absence of circulating corticosterone levels.(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of serotonin receptors in the amygdaloid complex and central gray substance in conditioned passive avoidance reaction in rats]

The functional role of 5-HT1 receptors in the memory trace retrieval was investigated in amygdala (AM), central gray substance of midbrain (CGS) and frontal cortex. There is used the passive avoidance response in the rat. The decrease of 5-HT1 binding sites in AM and CGS was revealed for the rats with retention of the passive avoidance response. The binding of 3H-5-HT in AM was found two sets of binding sites. It was concluded, that 5-HT1 receptors of AM and CGS are involved in learning processes either in the moment of the memory trace retrieval or immediately after it.

Ammonia and monoamine concentrations in two brain areas in rats after one hyperoxic seizure

Monoamines (catecholamines, serotonin, and metabolites) and ammonia were studied within two areas of the rat brain--the frontal cortex (FC) and the striatum (SA)--after exposure to hyperbaric oxygen (HBO) at 6 ATA up to the first seizure. An increase of norepinephrine (NE), dopamine (DA), and metabolites (HVA, DOPAC) measured by the HPLC/EC method were found in SA with a parallel increase of ammonia at variance with the FC where no monoamine changes, but a slight increase of ammonia, were found. Blood ammonia did not change with HBO. So, 20 min after one HBO seizure, there are regional differences in the brain, which are consistent with the previous findings of an SA start of electrocortical abnormalities at the onset of a seizure. Elevated DA, and possibly NE, levels may contribute to the accumulation of ammonia in the brain. During prolonged HBO exposure, this rise of ammonia could be one of the mechanisms involved in the relapse of seizures. It might also be implicated in initiation of the first seizure. By their situations and contents, SA glial cells could play an important role in brain HBO susceptibility.

An immunohistochemical localization of neuropeptide Y (NPY) in its amidated form in human frontal cortex

The distribution of neuropeptide Y (NPY)-immunoreactive neurons was studied in human frontal cerebral cortex from surgical biopsy specimens by immunohistochemical techniques. NPY-containing neurons were identified in all cortical sublayers except sublayer I. The stained neurons were of the multipolar, bitufted, round or triangular form with dendritic and axonal processes. The immunoreactive neurons were considered to be cortical interneurons, due to their nonpyramidal form, and since their processes could be followed intracortically particularly in direction to superficial cortical layers. The NPY precursor molecule is processed to NPY by a dibasic cleavage, and NPY is further enzymatically amidated before release and receptor activation can be achieved. Antisera raised against Cys-NPY(32-36)amide recognize amidated NPY not cross-reacting with nonamidated NPY. These antisera and immunohistochemistry revealed the presence of a population of NPYamide-immunoreactive cells morphologically indistinguishable from the NPY-immunoreactive cells in the human frontal cortex. By comparing the number of immunoreactive cells in adjacent sections, it appears that the number of NPY-immunoreactive cells was higher than those immunoreactive to NPYamide. Also, the density of NPY fibers was much higher compared with the number stained with NPYamide antiserum. The present immunohistochemical study indicates that NPY in its amidated form is contained in a subpopulation of human cortical NPY-immunoreactive neurons and may participate as an active neurotransmitter/modulator within the human cerebral cortex.

Monoclonal antibody to embryonic CNS antigen A2B5 provides evidence for the involvement of membrane components at sites of Alzheimer degeneration and detects sulfatides as well as gangliosides

Immunohistological and biochemical studies were initiated to determine whether or not neural membrane components were associated with degenerative changes characteristic of Alzheimer's disease (AD). Monoclonal antibody A2B5, developed against embryonic chick retinal cells and previously shown to react with neural surface gangliosides, was applied to formalin-fixed sections of control and AD brain tissue. Frontal cortex and hippocampus of AD cases exhibited high levels of A2B5 immunoreactivity within those neurons undergoing neurofibrillary degeneration. Neuritic processes associated with senile plaques were also highly reactive with the A2B5 antibody. The amount of gangliosides and their pattern after HPTLC were the same in control and AD cases. However, the unexpected observation was made that the A2B5 antibody reacted with human brain sulfatides in addition to the expected reactivity with minor gangliosides. The average level of sulfatides in AD brain was significantly higher than in normal controls. The data support the involvement of one or more membrane components with neurodegeneration in the Alzheimer brain.

Immunohistochemical quantification of the synapse-related protein synaptophysin in Alzheimer disease

Alzheimer disease (AD) as well as other dementing disorders are characterized by a continuous loss of neurons in cortical and subcortical areas and probably by an extensive synaptic loss. In order to substantiate and localize the loss of synapses in AD, we quantified by microdensitometry the neuropil immunoreactivity to an antibody that labels the protein synaptophysin (p38), which is localized in the presynaptic terminals. We found in the AD cases an average 50% decrease in the density of the granular neuropil immunoreaction in parietal, temporal and midfrontal cortex. In contrast, Pick disease cases presented close to normal values in parietal cortex, but major losses in temporal and frontal cortex. Our data strongly suggest an important role of synapse loss in dementia.

[5-HT1 receptors in rats with amnesia]

5-HT1 receptors of the amygdala, midbrain's central gray substance, hippocampus and frontal cortex of the rats were investigated during the memory trace retrieval, using the model of "psychogenic" amnesia. It was found that specific binding of 3H 5-HT in amygdala and central gray substance was decreased in the rats with passive avoidance retention. 3H 5-HT binding in the amnesic rats didn't differ from the control animals. Absence of decrease of 5-HT1 receptors number could be considered as one of the possible mechanisms of the memory trace non-retrieval due to amnesia or its consequence.

[The asymmetry of the free amino acid pool in sections of the rat brain]

The content of free amino acid pool in symmetric regions of cortex, hypothalamus, midbrain and blood of rats which had produced the movement conditioned reflex strengthened by feeding was studied. It was established that the "untrained" rats have higher content of free amino acid pool in their blood. The brain of the experimental animals revealed the biochemical asymmetry which was marked by the differences in free amino acid pool distribution between the left and right halves of the studied regions of brain. It was shown that left sided asymmetry animals i.e. animals with heightened content of free amino acid pool in the left half of the brain dominated in the "untrained" group of rats. The supposition was expressed that this biochemical asymmetry may contribute to the ability of animals to learn.

Regional variation in rat brain proton relaxation times and water content

Relaxation times (T1 and T2) and water content are measured in frontal cortex, amygdaloid cortex, hippocampus, mid-brain and cerebellum of rat brain. Differences are found in relaxation times, between areas containing a mixture of grey and white matter, and grey matter only. Differences were also found between certain grey matter areas. Relaxation times correlated with water content.

Basal forebrain efferents to the medial dorsal thalamic nucleus in the rhesus monkey

Thalamic efferent connections of the basal forebrain (BF); medial septal nucleus (MS), vertical limb of the diagonal band (VDB), horizontal limb of the diagonal band (HDB), nucleus basalis (NB), and ventral pallidum (VP) were investigated in twelve rhesus monkeys. In five animals, injections of radioactively labeled amino acids were placed in the BF. In four animals, the injections involved different divisions of the NB, HDB, and the most ventral part of the VDB. In those four cases, labeled fibers in the medial forebrain bundle were observed traveling caudally towards the hypothalamus where some turned dorsally to enter the inferior thalamic peduncle. These fibers terminated in the ventral half of the magnocellular part of the medial dorsal thalamic nucleus (MDmc). In a fifth case, the amino acid injection involved most of the MS and the VDB. Labeled fibers traveled caudally from the injection site and entered the stria medullaris. These fibers then traveled caudally before turning ventrally to terminate in the dorsal half of MDmc. To determine which of the diverse neuronal types in the BF gives rise to these thalamic projections, in two monkeys injections of horseradish peroxidase (HRP) were placed into MDmc. Labeled neurons were observed throughout the full extent of the NB, the VDB, the MS, and part of the VP. In order to determine the extent of the cholinergic input to MDmc from the BF, one of the HRP cases was processed for the simultaneous visualization of HRP, and acetylcholinesterase (AChE), the hydrolytic enzyme for acetylcholine, and a second case was processed for simultaneous visualization of HRP, and choline acetyltransferase (ChAT), the synthetic enzyme for acetylcholine. We observed that 30-50% of the HRP-labeled neurons were putatively cholinergic. In order to determine if the NB projection to MD is a collateral of the NB projection to orbital frontal cortex, one fluorescent retrograde tracer was injected into the orbital frontal cortex and one into MD. This case showed that approximately 5% of the BF neurons that project to MDmc also project to the orbital frontal cortex. These results confirm a significant subcortical projection by which the cholinergic system of the basal forebrain may influence higher cortical functions through the thalamus.

Dementia, parkinsonism, and motor neuron disease: neurochemical and neuropathological correlates

The neurochemical markers for the major neurotransmitter systems were measured in the brain of a patient who died with a dementia-parkinsonism-motor neuron disease (DPMN) syndrome complex. Moderate neuronal loss in the substantia nigra, spongiform changes in the frontal cortex, and moderate anterior horn cell loss throughout the spinal cord were observed. A severe nigrostriatal dopamine deficiency provides the basis for the observed parkinsonian features. The dementia is unexplained.

Identification of 5-hydroxytryptamine1A receptor proteins in bovine frontal cortex

5-Hydroxytryptamine1A (5-HT1A) receptor proteins were identified by a novel approach in which photoaffinity labeling technique was used in conjunction with affinity column chromatography. 5-HT1A receptors were solubilized from bovine frontal cortical membranes with 0.3% digitonin and 0.1% Nonidet P-40, and bound effectively to 1-[2-(4-aminophenyl)ethyl]-4-(3-trifluoromethylphenyl)piperazine (PAPP)-coupled Affi-Gel 10 in a time-dependent manner. PAPP was shown previously to be a selective ligand for the 5-HT1A receptor. Two protein bands with molecular masses of approximately 55,000 and 38,000 daltons revealed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were eluted from the affinity column with either 1 mM 5-HT or 1 microM [3H]1-[2-(4-azidophenyl)ethyl]-4-(3-trifluoromethyl-phenyl)piperazine ([3H]p-azido-PAPP). [3H]p-Azido-PAPP is a selective photoaffinity labeling probe for the 5-HT1A receptor. The intensity of these two protein bands and the incorporation of [3H]p-azido-PAPP into these two proteins decreased significantly when the solubilized fraction was preincubated with excess 5-HT or PAPP (saturating all 5-HT1A receptors) prior to affinity column chromatography. These results suggest strongly that these two proteins are related to the 5-HT1A receptor protein. The isoelectric points of the photolabeled 5-HT1A receptor proteins were 6.0 and 6.5.

Glycosaminoglycans in cortical autopsy samples from Alzheimer brain

Each of the known classes of mammalian glycosaminoglycans, with the exception of keratan sulphate, was found in cerebral cortex samples from patients with Alzheimer-type dementia and age-matched controls. These molecules were quantitated, after electrophoresis and staining with Alcian Blue dye, by scanning densitometry. No significant differences were found between the mean levels of each of the above glycosaminoglycans in frontal cortex from patients with dementia compared with controls. An increase (26%; p less than 0.05) in the mean level of hyaluronate, but not of other glycosaminoglycans, was found in temporal cortex samples. On the other hand, the uronic acid content of hyaluronate degradation products following Streptomyces hyaluronidase treatment of brain glycosaminoglycans did not reveal any statistically significant changes in Alzheimer's disease. HPLC of disaccharide products from Arthrobacter chondroitinase AC digests did not reveal any significant changes in sulphate substitution of chondroitin sulphate in Alzheimer brain.

Sex differences in passive avoidance depend on the integrity of the central serotonergic system

Effects of the neurotoxin para-chloroamphetamine (PCA) on sex differences in passive avoidance were studied. Seven days prior to passive avoidance training and testing, male and female rats were injected with PCA (5 mg/kg) or physiological saline (SAL). Treatment effects on brain monoamines levels were evaluated in brains collected shortly after the passive avoidance test. Compared to SAL-treated control groups PCA severely reduced both serotonin (5-HT) and 5-hydroxyindole-acetic acid (5-HIAA) in the frontal cortex of males and females. Levels of dopamine (DA) and homovanillic acid (HVA) in the frontal cortex were not affected. These data are indicative of a strong and selective depression of the central 5-HT activity. PCA- and SAL-treated male and female rats were trained and tested in a two-compartment step-through passive avoidance apparatus. Sex differences in passive avoidance were clearly observed in the SAL-treated control groups; a higher number of males did not enter either compartment within the maximum test duration. After PCA treatment sex differences in passive avoidance were abolished, mainly resulting from an increase in the number of PCA-males reentering. Irrespective of sex or treatment subjects seldom failed to choose the nonshock compartment when entering during the passive avoidance test, indicating that disturbance of memory or learning cannot explain for the present results. Rather, the data are discussed in terms of a sex-specific role of central 5-HT in punishment-induced behavioral suppression.

Layer-specific innervation of the dopamine-deficient frontal cortex in weaver mutant mice by grafted mesencephalic dopaminergic neurones

The dopamine innervation of the frontal cortex originates in the A9 and A10 mesencephalic dopamine cell groups. In weaver mutant mice, there is a 77% frontocortical dopamine deficiency associated with losses of dopamine neurones in areas A9 and A10. The dopamine-depleted cortical areas of weaver mutant mice are receptive to reinnervation by afferent fibres originating in dopamine-containing mesencephalic grafts from normal donor embryos. In the anteromedial frontal lobe, reinnervation by tyrosine hydroxylase immunoreactive fibres is largely confined to the basal cortical layers whereas in the anterior cingulate cortex, tyrosine hydroxylase immunoreactive fibres also occupy superficial layers, including the molecular layer. Normally, the dopaminergic innervation of the anteromedial frontal lobe is distributed among the basal cortical layers (IV-VI), and the dopaminergic innervation of the cingulate cortex occupies both basal and superficial cortical layers. The pattern of innervation following transplantation indicates that, in repopulating dopamine-deficient cortical areas of recipient weaver mutants, graft-derived dopamine fibres show a preference for those layers which are normally invested by dopamine afferents.

The alpha-tubulin of the growth cone is predominantly in the tyrosinated form

Growth cone cytoskeletons were prepared by detergent extraction of growth cones isolated from neonatal rat forebrain by the method of Gordon-Weeks and Lockerbie (Neuroscience, 13 (1984) 119-136). SDS-PAGE analysis of growth cone cytoskeletons revealed the presence of several major bands, identified by their mobility as actin (43 kDa Mr), myosin heavy chain (195 kDa Mr), spectrin (235 and 240 kDa Mr), and tubulin (51-54 kDa Mr). The identity of these proteins was confirmed by immunoblot analysis using specific antibodies to these proteins which further revealed that the predominant form of alpha-tubulin in the growth cone cytoskeleton and in the soluble pool of tubulin is tyrosinated at the C-terminal.

Distribution of serotonin immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko

The distribution of serotonin (5-hydroxytryptamine, 5-HT) in the forebrain and midbrain of the lizard Gekko gecko was studied by means of antibodies against serotonin. In the diencephalon, serotonin-immunoreactive (5-HTi) cell bodies were found in the hypothalamic periventricular organ and the ependymal wall of the infundibular recess. In the midbrain, 5-HTi cells were observed in the nucleus raphes superior and the lateral portion of the nucleus reticularis superior. In addition, 5-HTi cell bodies were found lateral to the ventral interpeduncular nucleus and around the ventral aspect of the medial longitudinal fasciculus. Serotonin-immunoreactive fibers and varicosities are present throughout the forebrain and the midbrain, but particularly in the nucleus accumbens, the septal area, the dorsal cortex, the dorsal thalamus, the lateral geniculate body, the ventromedial hypothalamic nucleus, the pretectal nucleus, and the basal optic nucleus. The medial habenular nucleus contains a dense 5-HTi plexus that shows a patchlike pattern. A laminar organization of 5-HTi fibers and varicosities is present in the midbrain tectum. When compared with data obtained in other vertebrates, the present study has confirmed that in the phylogenetic series fishes-amphibians-reptiles-birds-mammals there appears to be (1) a gradual decrease in the number of cerebrospinal-fluid-contacting serotoninergic cells in the hypothalamic periventricular layer and (2) a remarkable increase in number of serotoninergic cells in the midbrain tegmentum. As in mammals, a strong serotoninergic innervation of structures related to sensory, in particular visual, pathways could be recognized.

Distribution of dopamine immunoreactivity in the forebrain and midbrain of the snake Python regius: a study with antibodies against dopamine

The distribution of dopamine (DA) immunoreactivity in the forebrain and midbrain of the ball python, Python regius, was studied by using recently developed antibodies against DA. In order to determine general and species-specific features of the DA system in reptiles, we have selected the ball python as a representative of a reptilian radiation that hitherto has not been the subject of (immuno)histochemical studies. Dopamine-containing cell bodies were found around the glomeruli and in the external plexiform layer of both the main and accessory olfactory bulb, but not in the telencephalon proper. In the diencephalon, DA cells were observed in several parts of the periventricular hypothalamic nucleus, in the periventricular organ, the ependymal wall of the infundibular recess, the lateral hypothalamic area, the magnocellular ventrolateral thalamic nucleus, and the pretectal posterodorsal nucleus. In the midbrain, DA cells were found in the ventral tegmental area, the substantia nigra, and the presumed reptilian homologue of the mammalian A8 cell group. Dopaminergic fibers and varicosities were observed throughout the whole brain, particularly in the telencephalon and diencephalon. The nucleus accumbens, striatum, olfactory tubercle, and nucleus of the accessory olfactory tract appear to have the most dense innervation, but the lateral septal nucleus, the dorsal ventricular ridge, and the nucleus sphericus also show numerous DA-containing fibers and varicosities. Except for the lateral cortex, cortical areas are not densely innervated by DA fibers. The DA system of the snake Python regius shares many features with that of lizards and turtles as determined with the same antibodies. The taxonomically close relationship between lizards and snakes, which together constitute the Squamata, is reflected in a similar distribution of DA fibers and varicosities to the dorsal ventricular ridge and the lateral cortex, and in the limited number of CSF-contacting DA neurons in the hypothalamus.

The neurophysin-containing innervation of the forebrain of the mouse

The oxytocinergic and vasopressinergic innervation of the forebrain of normal mice was studied immunocytochemically by use of a set of mouse monoclonal anti-neurophysins applied to serial vibratome sections. The extensive hypothalamic and extra-hypothalamic location of these neuropeptides was revealed, with, or without colchicine pretreatment. Magnocellular perikarya immunoreactive for either oxytocin-neurophysin or vasopressin-neurophysin were concentrated mainly: in the anterior commissural nucleus; in various subdivisions of the paraventricular nucleus; in a profuse array in the periventricular region; in the supraoptic nucleus including its retrochiasmatic division; in various accessory nuclei; and as a number of cells scattered throughout the preoptic and hypothalamic regions. Extensive groups of parvocellular neurons, containing only vasopressin-neurophysin, were located in the suprachiasmatic nucleus including a ventromedial division, in the bed nucleus of the stria terminalis, and in the medial amygdaloid nucleus. Perikarya in the magnocellular nuclei were of generally similar size distribution and there was no evidence that distinct populations of magnocellular and parvicellular neurons, separable on the basis of size, had been labelled within these nuclei. Within the paraventricular nucleus, however, neurons in the posterior part were smaller than those located more anteriorly, and the cells containing oxytocin-neurophysin were slightly smaller than those containing vasopressin-neurophysin. Within the generally similar size distribution, magnocellular neurons of the anterior commissural nucleus were the largest. During processing, shrinkage of the tissue and immunolabeled cells had occurred. The immunocytochemical procedure delineated neuronal processes, in particular dendrites, very effectively. The dendrites were shown to project for far greater distances than is generally recognized, some were of a characteristic corkscrew-like morphology, and most were oriented in a well-defined pattern. Many dendrites of paraventricular neurons passed medially than caudally towards and then along the third ventricle. Most dendrites of supraoptic neurons, in particular those containing vasopressin-neurophysin, had an extensive anteroposterior course beneath the pia of the base of the brain. The axons containing oxytocin- and vasopressin-neurophysin were shown to take rather different paths from the paraventricular nucleus towards the median eminence.(ABSTRACT TRUNCATED AT 400 WORDS)

A postmortem study of the effect of chronic opiate abuse on psychotomimetic binding sites of human frontal cortex

Membranes were prepared from area 8 of human frontal cortex harvested from five controls and five opiate addicts. Psychotomimetic binding sites were assayed using tritiated 1-(1-[2-thiethyl]cyclohexyl)piperidine ([3H]TCP) to label phencyclidine binding sites and 1,3-Di(2-[5-3H]tolyl)guanidine ([3H]DTG) to label the "haloperidol-sensitive sigma binding site." The results demonstrated no significant differences between the control and experimental groups, suggesting that in the region of the human brain sampled in this study, chronic abuse of opiates is not accompanied by alterations in psychotomimetic binding sites.

Immunocytochemical localization of dopamine in the prefrontal cortex of the rat at the light and electron microscopical level

In the present study the dopaminergic innervation of the prefrontal cortex was studied by means of a recently developed anti-dopamine serum. This method can demonstrate endogenous dopamine in a specific way, and offers the opportunity to study the distribution of dopaminergic fibres in the cortex in detail in counterstained sections. Furthermore, dopaminergic nerve endings can be visualized at the electron microscopic level. Light microscopic observations demonstrated that the highest density of dopaminergic fibres in the frontal cortex is found in the prefrontal cortex and the infralimbic cortex. Within the prefrontal cortex, a good correlation is found between regional differences in distribution of dopaminergic fibres and the cytoarchitectonic parcellation of this part of the cortex. Outside the prefrontal cortex dopaminergic fibres were observed in adjacent frontal areas, the cortex surrounding the entire rhinal sulcus and the retrosplenial cortex. Electron microscopic observations demonstrated dopaminergic terminals through all cortical layers. The majority of dopaminergic terminals in the prefrontal cortex from synaptic contacts with dendritic processes. The synaptic profiles were usually symmetric and were characterized by the presence of many clear vesicles and an occasional dense-core vesicle.

Comparison of [125I]Bolton-Hunter neuropeptide Y binding sites in the forebrain of various mammalian species

The forebrain distribution of [125I]Bolton-Hunter (BH) neuropeptide Y (NPY) binding sites was compared in 4 mammalian species including rat, hamster, guinea pig and monkey. In all species studied, high densities of [125I]BH NPY binding sites were observed in the hippocampus. In this structure, [125I]BH NPY binding sites were distributed in a laminar fashion, with high densities seen in the oriens layer and stratum radiatum. However, species differences were seen in certain brain areas such as striatum, septum, thalamus and hypothalamus. These differences should be taken into account when studying central effects of neuropeptide Y.