A new approach to study angiotensin receptor distribution in the brain has been taken by developing antibodies to partial sequence of the angiotensin II (AII) type-1 receptor subtype (AT1) and demonstrating the presence of receptors with immunohistochemical staining. The antibody to a portion of the 3rd cytoplasmic loop of the AT1 receptor revealed distinctive punctate immunoreactive staining on cell bodies. The cell bodies were distributed in the forebrain in paraventricular and supraoptic nuclei, the organum vasculosum lamina terminalis, median preoptic area and subfornical organ. In the brainstem, the entire locus coeruleus was stained, together with the adjacent mesencephalic and motor nuclei of the trigeminal nerve. The auditory system including the cochlear nucleus and superior olivary nuclei were stained. In the medulla, all the structures involved in blood pressure control were stained including the nucleus of the solitary tract, the 12th nerve nuclei, the rostroventral lateral area and the nucleus ambiguous. Sites where AT2 receptors are located were not stained or staining was limited to specific area such as the medial accessory nucleus of the inferior olive. Immunocytochemical staining of AT1 receptors provides a new and more precise approach to the cellular localization of AII receptors.

The brainstem localization of acetylcholinesterase (AChE)-containing neurons projecting to the anteroventral thalamic nucleus (AVN) was studied in rats. The AVN is one of several forebrain regions innervated by the AChE-containing dorsal tegmental pathway described by Shute and Lewis. In the present study, horseradish peroxidase (HRP) was injected into the region of the AVN to determine the brainstem origin of afferent projections. Alternate sections of tissue were stained for HRP or AChE. HRP-labeled neurons were found in the laterodorsal tegmental nucleus (LTN) and the locus coeruleus. Examination of adjacent sections revealed AChE-containing neurons in both of these nuclear regions. Combined HRP/AChE histochemistry demonstrated that transported HRP and AChE were in the same cells. In further experiments, unilateral lesions of the LTN were found to cause a decrease in AChE staining of the ipsilateral AVN. Destruction of the locus coeruleus had no effect. In combination with available evidence, the present findings suggest that cholinergic neurons in the LTN innervate the AVN. © 1980, All rights reserved.

The present study was undertaken to investigate the origin of cocaine- and amphetamine-regulated transcript (CART) peptide immunoreactive (irCART) fibers observed in the nucleus of the solitary tract (NTS) and assess the role of CART peptide on phenylephrine (PE)-induced baroreflex. Immunohistochemical and retrograde tract-tracing studies showed that some of the irCART fibers observed in the NTS may have their cell bodies in the nodose ganglia. In urethane-anesthetized rats, intracisternal or bilateral intra-NTS microinjection of the CART peptide fragment 55-102 (0.1-3 nmol), referred to herein as CARTp, consistently and dose dependently attenuated PE-induced bradycardia. CARTp, in the doses used here, caused no significant changes of resting blood pressure or heart rate. Bilateral intra-NTS injections of CART antibody (1:500) potentiated PE-induced bradycardia. Injections of saline, normal rabbit serum, or concomitant injection of CARTp and CART antiserum into the NTS caused no significant changes of PE-induced baroreflex. The result suggests that endogenously released CARTp from primary afferents or exogenously administered CARTp modulates PE-induced baroreflex.

The purpose of these experiments was to determine the effects of cholinergic depletion on spontaneous and evoked activity of neurons in the different layers of the posteromedial barrel subfield (PMBSF) of the rat somatosensory cortex. Acetylcholine neurons in nucleus basalis of Meynert (NBM) were selectively lesioned with an immunotoxin (IT), 192 IgG-saporin. Spontaneous activity was significantly lower in layers II-III, Va, and VI in IT-injected animals compared to control animals. Evoked activity was significantly lower in layers II-III, IV, Vb, and VI of IT-injected animals compared to control animals. The largest difference was observed in layer Vb. Thus, cholinergic depletion causes significant changes in the magnitude of spontaneous and evoked activity but these differences are not completely in register with one another.

The discovery of mammalian protein prenylation was originally motivated by an effort to identify a nonsterol isoprenoid which indirect evidence suggested was a coregulator of isoprenoid biosynthesis and played a critical role in cellular proliferation. The first prenylated proteins to be identified were the nuclear lamin proteins-B lamins and prelamin A-which were subsequently shown to be farnesylated at a carboxyl-terminal CAAX motif. In both types of lamin, the farnesylation and carboxymethylation play a role in targeting these proteins to the nuclear envelope. The nucleus can be demonstrated to be a CAAX processing compartment for the lamins. In the case of prelamin A, there is removal of a carboxyl-terminal polypeptide which is specifically catalyzed by the enzyme Zmpste24. This processing event is necessary for assembly of lamin A into the lamina and may play a role in cell cycle control. Because the nucleus contains only one target membrane, lamin farnesylation and carboxymethylation may be sufficient to allow association with this membrane. This stands in contrast to farnesylated proteins expressed in the cytoplasm.

Previous electrophysiological studies of the basal ganglia in Parkinson's disease (PD) patients have utilized linear analyses in time-or-frequency domains to characterize neuronal discharge patterns. However, these measures do not fully describe the non-linear features of discharge rates and oscillatory activities of basal ganglia neurons.In this original research, we investigate whether non-linear temporal organizations exist in the inter-spike interval series of neurons recorded in the globus pallidus or the subthalamic nucleus in PD patients undergoing surgery for the implantation of deep brain stimulating electrodes.Our data indicate that in approximately 80% of globus pallidus and subthalamic neurons, the raw inter-spike interval sequences have lower entropy values than those observed after shuffling of the original series. This is the first report establishing non-linear temporal organization as a common feature of neuronal discharge in the basal ganglia of PD patients.

Baroreflex control of heart rate (HR) is impaired in human diabetes mellitus and in large experimental models. However, baroreflex impairment in diabetic mouse models and diabetes-induced remodeling of baroreflex circuitry are not well studied. We examined the impairment of baroreflex control of heart rate (HR) and assessed structural remodeling of cardiac ganglia in the streptozotocin (STZ)-induced diabetic mouse model. FVB mice were either injected with vehicle or STZ. Group 1: mice were anesthetized and the femoral artery and vein were catheterized at the 30th day after vehicle or STZ injection. On the second day after surgery, baroreflex-mediated HR responses to sodium nitroprusside (SNP) and phenylephrine (PE)-induced mean arterial blood pressure (MABP) changes were measured in conscious mice. Group 2: Fluoro-Gold was administered (i.p.) to label cardiac ganglia in each mouse at the 25th day after vehicle or STZ injection. After another five days, animals were perfused and cardiac ganglia were examined using confocal microscopy. Compared with control, we found in STZ mice: 1) the HR decreased, but MABP did not. 2) The PE-induced increases of MABP were decreased. 3) Baroreflex bradycardia was attenuated in the rapid MABP ascending phase but the steady-state ΔHR/ΔMABP was not different at all PE doses. 4) SNP-induced MABP decreases were not different. 5) Baroreflex tachycardia was attenuated. 6) The sizes of cardiac ganglia and ganglionic principal neurons were decreased. 7) The ratio of nucleus/cell body of cardiac ganglionic neurons was increased. We conclude that baroreflex control of HR is impaired in conscious STZ mice. In addition, diabetes may induce a significant structural remodeling of cardiac ganglia. Such an anatomical change of cardiac ganglia may provide new information for the understanding of diabetes-induced remodeling of the multiple components within the baroreflex circuitry.

Baroreflex control of heart rate (HR) is impaired in human type 1 diabetes mellitus. The goal of this study is to use a transgenic mouse model of type 1 diabetes (OVE26) to assess the diabetes-induced baroreflex impairment in the conscious state. OVE26 transgenic mice (which develop hyperglycemia within the first three weeks after birth due to the specific damage of beta cells) and normal control mice (FVB) 5-6 months of age were anesthetized, and the left femoral artery and both veins were catheterized. On the second day after surgery, baroreflex-mediated HR responses to arterial blood pressure (ABP) changes that were induced by separate microinfusion of phenylephrine (PE) and sodium nitroprusside (SNP) at different doses (0.03-0.4 μg/min) were measured in the conscious state. Compared with FVB control, we found that in OVE26 diabetic mice 1) mean ABP (MABP) and HR were decreased (p < 0.05). 2) PE-induced MABP increases were comparable to those in FVB mice (p > 0.05). 3) Baroreflex-mediated bradycardia was attenuated (p < 0.05). 4) SNP-induced MABP decreases was reduced (p < 0.05). 5) Baroreflex-mediated tachycardia was attenuated (p < 0.05). Since baroreflex control of HR in conscious OVE26 mice is impaired in a similar fashion to human diabetes mellitus, we suggest that OVE26 mice may provide a useful model to study the neural mechanisms of diabetes-induced baroreflex impairment.

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) offer unique, noninvasive methods of measuring, respectively, in vivo quantitative neuroanatomy and neurochemistry. The main purpose of the present study was to identify and compare the neuroanatomical and neurochemical abnormalities that are associated with prenatal exposure to alcohol in both fetal alcohol syndrome (FAS)-diagnosed children and those diagnosed with fetal alcohol effects (FAE). MR data of three age-, gender- and race-balanced groups of children, FAS-diagnosed, FAE-diagnosed and non-exposed controls, were compared. Effects of prenatal alcohol exposure, regardless of diagnosis, were found in the caudate nucleus. Specifically, a significantly smaller caudate nucleus was found for the FAS and FAE participants compared to the controls. In addition, the metabolite ratio of N-acetyl-aspartate to creatine (NAA/Cr), an indicator of neuronal function, in left caudate nucleus of both the FAS and FAE participants was elevated compared to the control group. Analysis of absolute concentrations revealed that the increase in the ratio of NAA/Cr was due to an increase in NAA alone. Although its exact function in the CNS is unknown, NAA is believed to be a neuronal marker due to its exclusive localization to neurons. Some also speculate a role for NAA in myelination. Elevated NAA in the prenatal alcohol-exposed participants could indicate a lack of normal program cell death, dendritic pruning and/or myelination during development. The present study demonstrates that prenatal alcohol-exposed children, with or without facial dysmorphology, have abnormal brain anatomy and chemistry.

Epidemiological studies implicate pesticide exposure as a possible etiologic factor in idiopathic Parkinson's Disease, which results from degeneration of nigrostriatal neurons, along with reduced levels of the neurotransmitter, dopamine. Behavioral and neurochemical analyses in C57BL6 mice were performed following a subchronic dosing regime with the organochlorine insecticide heptachlor or the pyrethroid deltamethrin. Results were compared to those induced by the established parkinsonian neurotoxicant, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). At the end of the treatment period, mice were assessed for effects on behavior, as well as levels of striatal dopamine, nerve terminal respiration, and synaptosomal dopamine transport. The primary behavioral effect of deltamethrin was incoordination, while heptachlor caused hyperexcitability and increased locomotion. The major neurochemical effect observed for both compounds was upregulation of the presynaptic dopamine transporter (DAT) by 70% and 100% for deltamethrin and heptachlor, respectively. The insecticides exerted only modest effects on striatal levels of dopamine and its metabolite, dihydroxyphenylacetic acid. However, doses of heptachlor higher than those which caused induction of DAT (e.g. greater than or equal to 25 mg/kg), when administered subchronically, were found to cause convulsions in some animals and caused marked, dose-dependent depression of basal striatal tissue respiration rates. No synergism was observed between the effects of insecticides and MPTP. Enhanced transport was thought to be a compensatory effect from increased release of transmitters by the insecticides, <i>in vivo</i>. Striatal dopamine, GABA and glutamate nerve terminals were differentially sensitive to the releasing effects of heptachlor compared to cortical serotonin terminals, and responded in the following rank order of sensitivity: dopamine > GABA > glutamate > serotonin. Additional experiments to characterize the mechanism(s) by which cyclodienes facilitate release of neurotransmitters in synaptosomes demonstrated a lack of distinct Ca²⁺ component and no involvement of retrograde DAT activity, suggesting that released label was of vesicular origin, but did not require Ca²⁺. Insecticidal toxicants, such as organochlorines and pyrethroids, which augment dopamine release and increase the maximal rate of dopamine uptake, may inundate the cytosol of nigrostriatal neurons with high concentrations of free dopamine, which has been shown by other researchers to induce apoptosis and may thereby contribute to the development of Parkinson's disease. Funding for this work was provided under grant number HHHREP 94-01 by the Hawaii Heptachlor Foundation, a non-profit organization. The Hawaii Heptachlor Foundation may be contacted at the following address: Ocean View Center PH#3, 707 Richards St., Honolulu, HI 96813. / Ph. D.