Ultrastructural Localization of Acetylcholinesterase in the Arcuate Nucleus and Median Eminence of the Rat

1977 ◽  
Vol 35 ◽  
pp. 440-441
Author(s):  
K.A. Carson ◽  
C.B. Nemeroff ◽  
M.S. Rone ◽  
J.S. Kizer ◽  
J.S. Hanker
Keyword(s):  
Choline Acetyltransferase ◽  
Median Eminence ◽  
Arcuate Nucleus ◽  
Cholinergic Neurons ◽  
Ultrastructural Localization ◽  
Male Rats ◽  
Neonatal Rats ◽  
Good Marker ◽  
Chemical Studies ◽  
High Doses

Biochemical, physiological, pharmacological, and more recently enzyme histo- chemical data have indicated that cholinergic circuits exist in the hypothalamus. Ultrastructural correlates of these pathways such as acetylcholinesterase (AchE) positive neurons in the arcuate nucleus (ARC) and stained terminals in the median eminence (ME) have yet to be described. Initial studies in our laboratories utilizing chemical lesioning and microdissection techniques coupled with microchemical and light microscopic enzyme histo- chemical studies suggested the existence of cholinergic neurons in the ARC which project to the ME (1). Furthermore, in adult male rats with Halasz deafferentations (hypothalamic islands composed primarily of the isolated ARC and the ME) choline acetyltransferase (ChAc) activity, a good marker for cholinergic neurons, was not significantly reduced in the ME and was only somewhat reduced in the ARC (2). Treatment of neonatal rats with high doses of monosodium 1-glutamate (MSG) results in a lesion largely restricted to the neurons of the ARC.

Differential effects of electrolytic and chemical hypothalamic lesions on LH pulses in rats

1988 ◽  
Vol 255 (5) ◽  
pp. E583-E590 ◽  
Author(s):  
C. L. Sisk ◽  
A. A. Nunez ◽  
M. M. Thebert
Keyword(s):  
Luteinizing Hormone ◽  
Median Eminence ◽  
Arcuate Nucleus ◽  
Neuronal Cell ◽  
Pulse Frequency ◽  
Male Rats ◽  
Immunocytochemical Staining ◽  
Neuronal Cell Bodies ◽  
Electrolytic Lesions ◽  
Lh Secretion

Electrolytic lesions of the arcuate nucleus were made in anesthetized adult castrated male rats. Luteinizing hormone (LH) pulse frequency averaged 2.4 pulses/h in controls but declined to a mean of 0.5 pulses/h in rats with bilateral damage to the arcuate nucleus. Because these lesions also damaged the median eminence, we tested the possibility that this disruption of LH secretion was due to coincidental damage to fibers of passage projecting to median eminence. Axon-sparing chemical lesions of the arcuate nucleus were made by intracranial injections of N-methyl-DL-aspartate (NMA) in anesthetized adult castrated rats. Mean LH pulse frequency was 2.3 and 2.5 pulses/h in control and NMA-injected rats, respectively. NMA injections destroyed arcuate neuronal cell bodies and produced a proliferation of glial cells within the nucleus. There was no apparent difference in the immunocytochemical staining intensity and distribution of luteinizing hormone-releasing hormone (LHRH) fibers in median eminence in rats receiving NMA or sham injections. These results suggest that the disruptive effects of electrolytic lesions of the arcuate nucleus on pulsatile LH secretion are a result of coincidental damage to LHRH neuronal projections to the median eminence and that neuronal cell bodies within the arcuate nucleus are not necessary for normal pulsatile LH secretion in male rats.

scholarly journals Spinal α2-Adrenoceptor-mediated Analgesia in Neuropathic Pain Reflects Brain-derived Nerve Growth Factor and Changes in Spinal Cholinergic Neuronal Function

2010 ◽  
Vol 113 (2) ◽  
pp. 406-412 ◽  
Author(s):  
Ken-ichiro Hayashida ◽  
James C. Eisenach
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Choline Acetyltransferase ◽  
Spinal Dorsal Horn ◽  
Acetylcholine Release ◽  
Cholinergic Neurons ◽  
Male Rats ◽  
Spinal Dorsal ◽  
Alpha2 Adrenoceptor

Introduction Spinal alpha2-adrenoceptor stimulation produces analgesia in neuropathic pain states, and this effect in animals is blocked by the inhibitors of brain-derived neurotrophic factor (BDNF) function. In rats, alpha2-adrenoceptor stimulation normally inhibits acetylcholine release, but it excites release after nerve injury. The authors examined the roles of BDNF and excitatory Gs-protein in this change. Methods Male rats underwent L5-L6 spinal nerve ligation (SNL), and their lumbar spinal dorsal horns with or without spinal BDNF infusion were used for either synaptosome preparation for acetylcholine release or immunostaining for choline acetyltransferase. Results SNL did not alter spontaneous release from synaptosomes or choline acetyltransferase immunoreactivity in the spinal dorsal horn, but it reduced KCl-evoked acetylcholine release. Dexmedetomidine inhibited KCl-evoked acetylcholine release in synaptosomes from normal rats, but it excited KCl-evoked release in synaptosomes from SNL rats, and both effects were blocked by the alpha2-adrenoceptor antagonist idazoxan. Spinal infusion of an antibody to BDNF reduced choline acetyltransferase immunoreactivity in the spinal dorsal horn in both normal and SNL rats and abolished facilitation of KCl-evoked acetylcholine release by dexmedetomidine in SNL rats. Dexmedetomidine facilitation of acetylcholine release was also blocked by the inhibitors of Gs function. Discussion The increased reliance of spinal alpha2 adrenoceptors on cholinergic stimulation to cause analgesia after nerve injury reflects in part a shift from direct inhibition to direct excitation of spinal cholinergic neurons. The authors' results suggest that this shift relies on an interaction with Gs-proteins and BDNF.

Effects of altered cholinergic function on working and reference memory in the rat

1986 ◽  
Vol 64 (3) ◽  
pp. 376-382 ◽  
Author(s):  
Richard J. Beninger ◽  
B. A. Wirsching ◽  
Khem Jhamandas ◽  
Roland J. Boegman ◽  
Sherif R. El-Defrawy
Keyword(s):  
Working Memory ◽  
Choline Acetyltransferase ◽  
Radial Maze ◽  
Cholinergic Neurons ◽  
Reference Memory ◽  
Nucleus Basalis ◽  
Nucleus Basalis Magnocellularis ◽  
Memory Errors ◽  
Biochemical Assays ◽  
Alternation Task

Many data suggest that the brain's cholinergic neurons participate in the control of memory and it has been suggested that cholinergic systems are involved differentially in working and reference memory. To test this hypothesis the effects on memory of unilateral injections of the neurotoxins, quinolinic acid or kainic acid into the cortically projecting cholinergic cells of the nucleus basalis magnocellularis (nbm) were evaluated. In experiment 1, quinolinate-injected (n = 7) and sham-operated (n = 7) rats were tested in a T-maze alternation task that requires working memory. Lesion rats performed significantly more poorly than shams and subsequent biochemical assays of cortical choline acetyltransferase (CAT) activity revealed significant reductions in the lesion rats. In experiment 2, kainate-injected (n = 9) and sham-operated (n = 8) rats were trained in an eight-arm radial maze with only four arms baited. Lesion rats made significantly more working memory errors (entries into baited arms from which the food had already been collected) than reference memory errors (entries into never baited arms). CAT assays showed that the lesion led to a decrease in cortical CAT with no significant change in hippocampal CAT. The results of these studies support the hypothesis that cholinergic neurons of the basocortical system may be differentially involved in working and reference memory.

scholarly journals A novel in vitro assay model developed to measure both extracellular and intracellular acetylcholine levels for screening cholinergic agents

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258420
Author(s):  
Ryohei Tanaka-Kanegae ◽  
Koichiro Hamada
Keyword(s):  
Cell Line ◽  
Neuroblastoma Cell ◽  
Cholinergic Neurons ◽  
Mechanisms Of Action ◽  
Neuroblastoma Cell Line ◽  
Ache Inhibitor ◽  
Vitro Assay ◽  
Food Ingredients ◽  
High Doses

Background Cholinergic neurons utilize choline (Ch) to synthetize acetylcholine (ACh) and contain a high-affinity Ch transporter, Ch acetyltransferase (ChAT), ACh receptors, and acetylcholinesterase (AChE). As the depletion or malfunction of each component of the cholinergic system has been reported in patients with dementia, many studies have sought to evaluate whether treatment candidates affect each of the cholinergic components. The associated changes in the cholinergic components may be reflected by intra- or extra-cellular ACh levels, with an increase in extracellular ACh levels occurring following AChE inhibition. We hypothesized that increases in intracellular ACh levels can be more sensitively detected than those in extracellular ACh levels, thereby capturing subtle effects in the cholinergic components other than AChE. The objective of this study was to test this hypothesis. Methods We developed an in vitro model to measure both extracellular and intracellular ACh levels using the human cholinergic neuroblastoma cell line, LA-N-2, which have been reported to express Ch transporter, ChAT, muscarinic ACh receptor (mAChR), and AChE. With this model, we evaluated several drug compounds and food constituents reported to improve cholinergic function through various mechanisms. In addition, we conducted western blotting to identify the subtype of mAChR that is expressed on the cell line. Results Our cell-based assay system was capable of detecting increases in extracellular ACh levels induced by an AChE inhibitor at relatively high doses, as well as increases in intracellular ACh levels following the administration of lower AChE-inhibitor doses and an mAChR agonist. Moreover, increases in intracellular ACh levels were observed even after treatment with food constituents that have different mechanisms of action, such as Ch provision and ChAT activation. In addition, we revealed that LA-N-2 cells expressed mAChR M2. Conclusion The findings support our hypothesis and indicate that the developed assay model can broadly screen compounds from drugs to food ingredients, with varying strengths and mechanisms of action, to develop treatments for ACh-relevant phenomena, including dementia and aging-related cognitive decline.

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