Non-specific Cholinesterase Research Articles

Butyrylcholinesterase levels correlate with surgical site infection risk and severity after colorectal surgery: a prospective single-center study.

Surgical site infections (SSIs) after colorectal surgery remain a significant concern, which warrants effective predictive markers for prompt diagnosis and treatment. Butyrylcholinesterase (BChE), a non-specific cholinesterase enzyme, has been correlated with the risk of hepatic dysfunction progression and, more recently, infectious diseases and septic shock with ongoing research into the utility of BChE in multiple systemic inflammatory conditions. Whether these preliminary results can be translated into predicting infection after colorectal surgery remains in remains in question. This prospective study aimed to assess BChE's potential as a predictive marker for surgical site infections and anastomotic leaks after colorectal surgery. This single-center prospective study (11/2019-05/2023) enrolled 402 patients who underwent colorectal surgery. BChE levels were measured at four postoperative time points. The primary endpoints focused on BChE's association with complications, particularly surgical site infections (SSIs). Further known predictors of SSI were utilized to construct multivariable models to assess for independent association with SSI development. During the third and fifth day postsurgery, SSI patients had significantly lower mean BChE levels (3.90 KU/L vs. 4.54 KU/L p-value < 0.05, and 4.14 KU/L vs. 4.73 KU/L, p-value < 0.05; t-test, respectively). However, multivariate analysis revealed that when adjusted for other factors, low BChE levels on the first postoperative day were associated with 2.6 times higher odds of developing SSI (OR: 2.6, 95%CI: 1.3-3.9, p-value < 0.05). Similar results were found for low BChE levels on the third postoperative day as they were associated with a. 2.53 times higher odds for developing SSI (OR: 2.5, 95%CI: 1.27-3.87, p-value < 0.05) when adjusted for other factors. In conclusion, in this prospective observational study, low levels in the first and third postsurgery were associated with an increased risk for the development of SSIs but not sepsis.

Distribution, fine structure, and three-dimensional innervation of lamellar corpuscles in rat plantar skin.

Lamellar corpuscles function as mechanoreceptors in the skin, composed of axon terminals and lamellae constructed by terminal Schwann cells. They are classified into Pacinian, Meissner, and simple corpuscles based on histological criteria. Lamellar corpuscles in rat dermal papilla cells have been reported; however, the morphological aspects have yet to be thoroughly investigated. In the present study, we analyzed the enzyme activity, distribution, fine structure, and three-dimensional innervation of lamellar corpuscles in rat plantar skin. The lamellar corpuscles exhibiting non-specific cholinesterase were densely distributed in rat footpads, evident as notable skin elevations, especially at the apex, the highest portion of the ridges in each footpad. In contrast, only a few lamellar corpuscles were found in other plantar skin areas. Lamellar corpuscle was considered composed of a flat axon terminal Schwann cell lamellae, which were roughly concentrically arranged in the dermal papilla. These histological characteristics correspond to those of the simple corpuscle. Moreover, the axon tracing method revealed that one trunk axon innervated several simple corpuscles. The territory of the trunk axons overlapped with each other. Finally, the animals' footprints were analyzed. During the pausing and walking phases, footpads are often in contact with the floor. These results demonstrate that the type of lamellar corpuscles in the dermal papillae of rat plantar skin is a simple corpuscle and implies that their distribution pattern in the plantar skin is convenient for efficient sensing and transmission of mechanical stimuli from the ground.

Identification of Compounds for Butyrylcholinesterase Inhibition.

Butyrylcholinesterase (BChE) is a nonspecific cholinesterase enzyme that hydrolyzes choline-based esters. BChE plays a critical role in maintaining normal cholinergic function like acetylcholinesterase (AChE) through hydrolyzing acetylcholine (ACh). Selective BChE inhibition has been regarded as a viable therapeutic approach in Alzheimer’s disease. As of now, a limited number of selective BChE inhibitors are available. To identify BChE inhibitors rapidly and efficiently, we have screened 8998 compounds from several annotated libraries against an enzyme-based BChE inhibition assay in a quantitative high-throughput screening (qHTS) format. From the primary screening, we identified a group of 125 compounds that were further confirmed to inhibit BChE activity, including previously reported BChE inhibitors (e.g., bambuterol and rivastigmine) and potential novel BChE inhibitors (e.g., pancuronium bromide and NNC 756), representing diverse structural classes. These BChE inhibitors were also tested for their selectivity by comparing their IC50 values in BChE and AChE inhibition assays. The binding modes of these compounds were further studied using molecular docking analyses to identify the differences between the interactions of these BChE inhibitors within the active sites of AChE and BChE. Our qHTS approach allowed us to establish a robust and reliable process to screen large compound collections for potential BChE inhibitors.

Evaluation of Serum Cholinesterase Level as A diagnostic Marker in Chronic Liver Disease

Background: Liver is the main source of Butyrylcholinesterase (serum cholinesterase). It is a non-specific cholinesterase that is reduced in patients with advanced liver diseases. Measurement of serum Butyrylcholinesterase activity serves as a sensitive indicator of synthetic capacity of the liver. Objective: To evaluate serum cholinesterase levels in chronic liver disease patients. Patients and methods: In this study serum cholinesterase level was evaluated in chronic liver disease patients by a colorimetric kinetic assay method. Thirty cirrhotic subjects and thirty non-cirrhotic hepatic disease subjects were compared to 20 normal individuals. This study was done at Al-Azhar University Hospitals in the period between June 2018 and August 2020. Results: A significant decrease in serum Cholinestrease level was observed in all patients of chronic liver disease as compared to control group. Conclusion: Serum cholinesterase is a better diagnostic and prognostic marker than the conventional liver function test that are raised in other liver disease also.

PSEUDOCHOLINESTERASE AS A PREDICTOR MARKER IN HYPOTHYROID PATIENTS

Introduction: Hypothyroidism is due to decreased circulating levels of Thyroid hormones and is caused by inadequate functioning of thyroid gland. Pseudocholinesterase (PCHE) is a nonspecific cholinesterase enzyme that hydrolyses choline based esters in plasma. The purpose of this study was to evaluate the serum level of PCHE in hypothyroid patients. Methodology: The present study was conducted on 100 newly diagnosed hypothyroid patients attending the Medical OPD. The results of patients were compared with 100 healthy controls of either sex of similar age group. Anthropometric measurements, T3, T4, TSH, PCHE &amp; Cholesterol estimations were performed. Results: The mean serum PCHE (decrease) level was observed statistically highly significant (p&lt;0.001) in hypothyroid patients as compared with healthy control subjects. A highly significant positive correlation between PCHE with T3 &amp; T4 (p&lt; 0.001) in hypothyroid cases. Conclusion: Serum Pseudocholinesterase may be helpful as biomarker in screening test for hypothyroidism along with thyroid stimulating hormone.

Pseudocholinesterase, aspartate transaminase, alanine transaminase as markers for cervical cancer: a study in a tertiary care hospital

Background: Cervical cancer is a malignant neoplasm arising from cells originating in the cervix, almost always caused by human papillomavirus (HPV). Butyrylcholinesterase is a non-specific cholinesterase enzyme that hydrolyses different choline esters. PCHE levels were lower than the normal at all the stages of cancer cervix. The present study was attempted to find out the role of some of the biochemical markers like serum pseudocholinesterase (PCHE), serum aspartate transaminase (AST), and serum alanine transaminase (ALT), in malignancy of the uterine cervix.Methods: 60 patients aged between 30 -70 years who were having cervical cancer were included into the study and 30 healthy patients within the same age group were included as controls. 5ml of venous blood was collected from all the study participants under aseptic conditions in a plain tube. Serum Pseudocholinesterase, Serum Aspartate transaminase and Serum Alanine transaminase was estimated for all the patients in both the groups.Results: The mean value of pseudocholinesterase in cervical cancer patients was lower in the cases when compared to controls and it was statistically significant (P value 0.0005), while the mean value of serum AST and ALT were higher in cases when compared to controls and it were also statistically significant. When compared with Pearson’s coefficient, the serum PChE had a significant negative correlation with AST and ALT, while the serum AST had a significant positive correlation with ALT and a negative correlation with PChE.Conclusions: Among the women with cervical cancer, it was observed that the enzyme activity of PChE was lower than normal, while that of SGPT and SGOT were higher. PCHE, AST, and ALT can be used as tumor markers in the management of malignancy of the uterine cervix.

Butyrylcholinesterase blood plasma concentrations of Common Swifts (Apus apus)

Butyrylcholinesterase (BChE), known as pseudocholinesterase or plasma cholinesterase, is a non-specific cholinesterase enzyme synthesised in the liver. The function of this enzyme is unknown in detail and is primarily discussed as a safeguarding system for Acetylcholinesterase (AChE). In a retrospective analysis of results of blood chemistry investigations of wild bird patients of the Clinic for Small Mammals, Reptiles and Birds, University of Veterinary Medicine Hannover, Foundation, Germany, BChE plasma concentrations of the Common Swift (Apus apus) and a possible influence of the body condition and age were determined. Blood values of adult (n = 33) and juvenile (n = 50) Common Swifts were analysed. BChE was determined by dry chemistry analyser Kodak Ektachem DTSC II module® with slides with butyrylthiocholin as substrate and measured at 400 nm by reflectance spectrophotometry during 5-min incubation at 37 °C. The Common Swift could be determined as a species with very high BChE blood plasma concentrations compared to other insectivore species. The arithmetic mean ± standard deviation (SD) for adult swifts amounted to 27,189.28 U/l ± 10,852.94 and that for juvenile/fledged swifts to 25,986.54 U/l ± 9573.28. A remarkable influence of the body condition on this BChE plasma concentration could be observed. In cases of malnutrition, a highly significant decrease of BChE activity could be found. For example, BChE concentrations of adult swifts in a poor body condition with reduced total protein and albumin blood plasma concentrations without liver diseases, arithmetic mean ± SD, 14,837.13 U/ l ± 7944.45, illustrate this impact.

7-Methoxytacrine-p-Anisidine Hybrids as Novel Dual Binding Site Acetylcholinesterase Inhibitors for Alzheimer’s Disease Treatment

Alzheimer’s disease (AD) is a debilitating progressive neurodegenerative disorder that ultimately leads to the patient’s death. Despite the fact that novel pharmacological approaches endeavoring to block the neurodegenerative process are still emerging, none of them have reached use in clinical practice yet. Thus, palliative treatment represented by acetylcholinesterase inhibitors (AChEIs) and memantine are still the only therapeutics used. Following the multi-target directed ligands (MTDLs) strategy, herein we describe the synthesis, biological evaluation and docking studies for novel 7-methoxytacrine-p-anisidine hybrids designed to purposely target both cholinesterases and the amyloid cascade. Indeed, the novel derivatives proved to be effective non-specific cholinesterase inhibitors showing non-competitive AChE inhibition patterns. This compounds’ behavior was confirmed in the subsequent molecular modeling studies.

Pseudocholinesterase as a prognostic marker for liver disorder

Background: Liver is the main source of pseudo cholinesterase. It is a non-specific cholinesterase found in the blood plasma and may be reduced in patients with advanced liver diseases. Measurement of serum pseudo cholinesterase activity serves as a sensitive indicator of synthetic capacity of the liver and can be used as a prognostic marker for carcinoma.Objective: To study pseudo cholinesterase activities in liver diseases.Method: A prospective study was conducted at College of Medical Sciences Teaching Hospital (CMS-TH), from May 2011 to May 2013 with 25 controls and 25 diagnosed cases each of carcinoma of liver, cirrhosis of liver, infective hepatitis and obstructive jaundice among both sexes of same age group attending medical outpatient and inpatient departments. Serum pseudo cholinesterase and other liver function tests were performed with semi-auto analyzer and Roche Hitachi 902 respectively.Results: Pseudo cholinesterase level was markedly decreased in carcinoma of liver (mean ± SD = 1369.48 ± 276.64 IU/L) followed by cirrhosis of liver (mean ± SD = 1735.16 ± 433.82 IU/L), infective hepatitis (mean ± SD = 3800.69 ± 764.17 IU/L), obstructive jaundice (mean ± SD = 5539 ± 791.05 IU/L) when compared with controls (mean ± SD = 6865.12 ± 928.41 IU/L). The difference in the means was statistically significant (p &lt;0.001).Conclusion: There was significant decrease in pseudo holing esterase level in carcinoma of liver followed by cirrhosis of liver while less so in infective hepatitis. In obstructive jaundice the enzyme level was found to be decreased but higher than other liver diseases. The results indicated that with more severe liver cell destruction or cell degeneration, there was corresponding significant decrease in the level of pseudo cholinesterase, which could be used as diagnostic marker of liver disease.Journal of Kathmandu Medical College Vol. 3, No. 4, Issue 10, Oct.-Dec., 2014Page: 131-135

Differential cell‐specific location of Cav‐1 and Ca2+‐ATPase in terminal Schwann cells and mechanoreceptive Ruffini endings in the periodontal ligament of the rat incisor

Caveolae are involved in clathrin-independent endocytosis, transcytosis, signal transduction, and tumor suppression - all of which depend on their main constituent protein caveolin families. The periodontal Ruffini ending has been reported to develop a caveola-like structure on the cell membrane of both the axon terminals and Schwann sheaths, suggesting the existence of an axon-Schwann cell interaction in the periodontal Ruffini endings. However, little information is available concerning the functional significance of these caveolae. The present study was undertaken to examine the immunolocalization of caveolin-1, -3 (Cav-1, Cav-3) and Ca(2+)-ATPase in the periodontal Ruffini endings of the rat incisor. Decalcified sections of the upper jaws were processed for immunocytochemistry at the levels of light and electron microscopy. Some immunostained sections were treated with histochemistry for nonspecific cholinesterase (nChE) activity. Observations showed the periodontal Ruffini endings were immunopositive for Cav-1, but not Cav-3. Immunoreactive products for Cav-1 were confined to caveola-like structures in the cell membranes of the cytoplasmic extensions and cell bodies of the terminal Schwann cells associated with the periodontal Ruffini endings. However, the axonal membranes of the terminals did not express any Cav-1 immunoreaction. Double staining with Ca(2+)-ATPase and either protein gene product 9.5 (PGP 9.5) or S-100 protein disclosed the co-localization of immunoreactions in the axonal branches of the periodontal Ruffini endings, but not in the terminal Schwann cells. As Ca(2+) plays an important role in mechanotransduction, these characteristic immunolocalizations show Cav-1/Ca(2+)-ATPase might be involved in the quick elimination of intracellular Ca(2+) in mechanotransduction.

Immunohistochemical detection of ENaCβ in the terminal Schwann cells associated with the periodontal Ruffini endings of the rat incisor

Epithelial sodium channels (ENaCs) are a subfamily of ion channels within the degenerin/ENaC (DEG/ENaC) superfamily. Previous studies have shown the immunolocalization of ENaC in the neural elements of the cutaneous mechanoreceptors as well as dorsal root and trigeminal ganglion neurons, indicating the involvement of this molecule in mechanotransduction. The present study examined the expression of ENaCbeta, a major component of ENaC protein, in the mechanoreceptive Ruffini endings in the periodontal ligament of the rat incisors by immunohistochemistry. The expression of ENaCbeta in the trigeminal ganglion--which innervates the periodontal Ruffini endings--was also investigated at the mRNA and protein levels. Furthermore, double staining and a nerve injury experiment were applied to clarify its detailed localization in the periodontal Ruffini endings. ENaCbeta immunoreaction in the trigeminal ganglion was recognizable in the comparatively large neurons which have been considered to mediate mechanotransduction. Immunohistochemistry for ENaCbeta demonstrated dendritic ramifications of the Ruffini endings as well as the rounded cells in the periodontal ligament. Double staining with ENaCbeta and either PGP9.5 or S-100 protein showed immunoreaction for ENaCbeta in both the axonal and glial elements in the periodontal ligament. Some ENaCbeta positive cells with rounded profiles were reactive to non-specific cholinesterase activity. Furthermore, a transection of the inferior alveolar nerve failed to eliminate the rounded cells with ENaCbeta reaction, indicating that they were the terminal Schwann cells associated with the periodontal Ruffini endings. These findings suggest that ENaCbeta is a key mechanotransducing channel in the periodontal Ruffini endings. Probably, the terminal Schwann cells together with the axon terminals regulate mechanotransduction in the periodontal endings.

Immunohistochemical detection of nestin in the periodontal Ruffini endings of the rat incisor

Nestin is an intermediate filament which was first identified in neuroepithelial stem cells. This expression has also been reported in restricted locations in adults. Previous studies have suggested that the periodontal Ruffini endings remain immature in nature even in adulthood. The present study reports on a characteristic expression of immunoreaction for nestin in the periodontal Ruffini endings during postnatal development. RT-PCR analysis detected nestin mRNA in a reverse transcripted cDNA sample from both the rat trigeminal ganglion and periodontal ligament. The nestin immunoreaction existed in the periodontal ligament at postnatal day 3 (PO 3 days), when many spindle-shaped Schwann cells were positive for nestin immunoreaction. At PO 1 week, when periodontal nerve fibers displayed a dendritic fashion, the round cells came to show the nestin immunoreaction. These immunopositive cells were also reactive for S-100 protein and non-specific cholinesterase, indicating that these cells could be categorized as terminal Schwann cells associated with the periodontal Ruffini endings. Some ordinary Schwann cells also exhibited nestin immunoreaction. From PO 2 to 3 weeks, nestin positive terminal Schwann cells increased in number in accordance with the postnatal development of the periodontal Ruffini endings, while this immuno-expression pattern remained unchanged. Nestin immunoreaction was also recognizable in the satellite cells – but never in the neurons – in the trigeminal ganglion throughout this observation period. This immuno-expression pattern suggests that nestin serves as an intermediate filament for mechanical stability in the periodontal Ruffini endings against external stimuli.

Cholinesterase Inhibitors: From Weapons, to Pesticides, to Cognition Enhancing Drugs

Chemistry, pharmacology and applications of compounds inhibiting enzymatic acetylcholine (ACh) degradation are reviewed. Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), or non-specific cholinesterase, are members of the family of cholinesterase (ChE), the ACh degrading enzymes. ChE inhibitors (is) are compounds inhibiting reversibly or irreversibly enzymatic ACh breakdown. The first ChE-is were organophosphate derivatives, synthesized as neurotoxic agents. These compounds cause toxic accumulation of ACh at the central and autonomic nervous system level and induce several neurological and autonomic effects including ataxia, seizures, coma, and respiratory depression. This strong toxicity is the reason of their identification as warfare agents. The subsequent main use of ChE-is was as pesticides. ChEs are important enzymes needed for proper functioning of insect nervous system. Although ChE-is are intended for insect pests, in some situations they can be poisonous or toxic to humans. The most recent and promising use of AChE/BuChE-is was symptomatic treatment of cognitive dysfunction occurring in Alzheimers disease (AD). Forebrain cholinergic system has a key role in learning and memory and AD is characterized by brain cholinergic impairment. AChE/BuChE-is are the first drugs approved for symptomatic treatment of cognitive deficits in AD. Besides cognitive relief induced in mild-to-moderate AD, increasing evidence suggests that ChE-is may interfere with the progression of the disease. If this hypothesis will be supported by ongoing studies, these compounds could become a disease-modifying strategy in the treatment of adult-onset dementia. Keywords: Acetylcholine, acetylcholinesterase, acetylcholinesterase/cholinesterase inhibitors, weapons, pesticides, Alzheimer's disease treatment

Expression of GDNF and its receptors in the periodontal mechanoreceptor

Our previous studies have revealed the involvement of signaling pathways of BDNF and NT-4/5 via TrkB in the development, regeneration, survival and maintenance of the Ruffini endings, primary mechanoreceptors in the periodontal ligament. However, the involvement of other neurotrophins remains unclear. The present study examined the expression of GDNF, GFRα1, and RET in the incisor periodontal ligament and trigeminal ganglion of young rats by RT-PCR and immunocytochemistry. All these mRNAs were detected in both tissues by RT-PCR. These immunoreactions were found in the terminal Schwann cells associated with the periodontal Ruffini endings, as confirmed by histochemistry for non-specific cholinesterase activity. Their axonal branches showed GFRα1- and RET-immunoreactions but lacked GDNF-immunoreactivity. In the trigeminal ganglion, about 30% of the neurons were immunoreactive to GFRα1 and RET. Averages of cross-sectional areas of their positive neurons demonstrated that they could mainly be categorized as medium-sized neurons. GDNF-immunoreaction was restricted to the satellite cells and not in trigeminal ganglion neurons. These findings indicate that GDNF mediates trophic effects on the survival and target innervation of the periodontal Ruffini endings via GFRα1 and RET.

Neurotrophin-4/5-depletion induces a delay in maturation of the periodontal Ruffini endings in mice

Neurotrophin-4/5 (NT-4/5) - a member of the neurotrophic factors - is a ligand for TrkB, which has been reported to be expressed in the mechanoreceptive Ruffini endings of the periodontal ligament. The present study examined developmental changes in the terminal morphology and neural density in homozygous mice with a targeted disruption of the nt-4/5 gene and wild-type mice by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general neuronal marker, and by quantitative analysis using an image analyzer. Postnatal development of terminal Schwann cells was also investigated by enzymatic histochemistry for non-specific cholinesterase activity (ChE). Furthermore, the immuno-expression of TrkB and low affinity nerve growth factor receptor (p75-NGFR) was surveyed in the periodontal Ruffini endings as well as trigeminal ganglion. At postnatal 1 week, the lingual periodontal ligament of both types of mice contained PGP 9.5-positive nerve fibers showing a tree-like ramification with axonal swellings in their course. In both types of mice at 2 weeks of age, comparatively thick nerve fibers with a smooth outline increased in number, and frequently ramified to form nerve terminals with dendritic profiles. However, no typical Ruffini endings with irregular outlines observed in the adult wild-type mice were found in the periodontal ligament at this stage. At postnatal 3 weeks, typical Ruffini endings with irregular outlines were discernable in the periodontal ligament of the wild-type mice while the dendritic endings showing smooth outlines were restricted to the homozygous mice. After postnatal 8 weeks, both types of mice showed an increase in the number of Ruffini endings, but the morphology differed between the wild-type and NT-4/5 homozygous mice. In the wild-type mice, a major population of the Ruffini endings expanded their axonal branches and developed many microprojections, resulting in a reduction of endings with smooth outlines. In contrast, we failed to find such typical Ruffini endings in the periodontal ligament of the homozygous mice: A majority of the periodontal Ruffini endings continued to show smooth outlines at postnatal 12 weeks. Quantitative analysis on neural density demonstrated a reduction in the homozygous mice with a significant difference by postnatal 8 weeks. Enzymatic histochemistry for non-specific ChE did not exhibit a distinct difference in the distribution and density of terminal Schwann cells between wild-type and homozygous mice. Furthermore, TrkB and p75-NGFR mRNA and proteins did not differ in the trigeminal ganglion between the two types. The periodontal Ruffini endings also displayed immunoreactivities for TrkB and p75- NGFR in both phenotypes. These findings suggest that the nt-4/5 gene depletion caused a delay in the formation and maturation of the periodontal Ruffini endings in the mice by inhibiting the growth of the periodontal nerves at an early stage, and indicate that multiple neurotrophins such as NT- 4/5 and BDNF might play roles in the development and/or maturation of the periodontal Ruffini endings.

Standardization of clinical cholinesterase measurements.

Previous studies showed that commonly used kits for measuring cholinesterases were not optimal for determining acetylcholinesterase (AChE) activity. Clinical use of different kits and methodologies resulted in AChE levels being reported in different units and activities that were not reproducible among laboratories. Findings such as these led to a revision in California regulations (covering AChE measurements for pesticide worker safety) calling for clinical laboratories to standardize their findings. The laboratories were contacted and invited to participate in a split-sample study of human blood AChE and nonspecific cholinesterase (BChE) assays. Participating laboratories measured erythrocyte (RBC) AChE and/or plasma BChE from undiluted and 50% diluted blood, according to their practices. Aliquots of blood samples were shipped to University of California Davis for measurement, using an optimized semiautomated plate reader version of the method of Ellman. Nine of 25 laboratories sent samples for comparison. Two others performed their own comparisons and submitted data to the state. Best correlations were obtained with BChE activity. Correlations (r(2)) were .88 or above for four of five laboratories for BChE, and above .9 for two of seven laboratories for AChE. Reasons for poor correlations may include difficulties in pipetting RBCs, storage, and processing. A bovine AChE RBC ghost "standard" was devised and tested. Activity of the preparation was maintained at -70 degrees C for approximately 11 months. A test with an East coast laboratory resulted in a high correlation, demonstrating the reliability of the RBC ghost standard and that one laboratory can replicate the AChE findings of another. The overall poor correlation of interlaboratory cholinesterase results points to the need to further standardize sample handling and assay methods.

The development of terminal Schwann cells associated with periodontal Ruffini endings in the rat incisor ligament.

The postnatal development of the terminal Schwann cell, an analogue of the lamellar cell in cutaneous sensory receptors, was examined by histochemistry for non-specific cholinesterase and immunohistochemistry for S-100 protein in the periodontal Ruffini endings of the rat incisor. Double immunohistochemistry for S-100 protein and protein gene product 9.5 (PGP 9.5) was also performed to examine the relationship between terminal Schwann cells and axons. Histochemistry for non-specific cholinesterase was able to demonstrate the age-related development of the terminal Schwann cells; the morphology and distribution of the developing terminal Schwann cells became almost identical to those in adults during postnatal days 15-18. Axons showing PGP 9.5-like immunoreactivity elongated and expanded after arrangement of terminal Schwann cells in the alveolus-related part. This suggests that the terminal Schwann cell is important in the development and maturation of the periodontal Ruffini endings.

Purification, characterisation, and inhibition by monoterpenes of acetylcholinesterase from the waxmoth, Galleria mellonella (L.)

Acetylcholinesterase (AChE) was purified from the brain of the waxmoth, Galleria mellonella (L.) by affinity chromatography followed by anion exchange chromatography. It resolved as a single band by polyacrylamide gel electrophoresis (PAGE) both non-denaturing and SDS (silver stained), and as a single peak by high pressure liquid chromatography (HPLC), in an overall yield of 32% representing 283-fold purification. This was a true acetylcholinesterase, with no activity as a non-specific cholinesterase (butyrylcholinesterase). The molecular weight determined by PAGE in the absence and presence of sodium dodecyl sulphate (SDS) was ca. 240,000 Da and 60,000 Da respectively, indicating an arrangement of tetrameric subunits. 2-Heptanone, the honeybee alarm pheromone, reversibly and competitively inhibited the purified Galleria AChE with a K i value of 1.34×10 −3 M. Furthermore, five monoterpenes associated with plant defence and representing a range of functional groups, also were reversible competitive inhibitors of the purified AChE from Galleria, which is consistent with previous data for electric eel AChE (Ryan, M.F., Byrne, O., 1988. Plant-insect coevolution and inhibition of acetylcholinesterase. Journal of Chemical Ecology 14, 1965-1975).

The Ruffini ending as the primary mechanoreceptor in the periodontal ligament: its morphology, cytochemical features, regeneration, and development.

The periodontal ligament receives a rich sensory nerve supply and contains many nociceptors and mechanoreceptors. Although its various kinds of mechanoreceptors have been reported in the past, only recently have studies revealed that the Ruffini endings--categorized as low-threshold, slowly adapting, type II mechanoreceptors--are the primary mechanoreceptors in the periodontal ligament. The periodontal Ruffini endings display dendritic ramifications with expanded terminal buttons and, furthermore, are ultrastructurally characterized by expanded axon terminals filled with many mitochondria and by an association with terminal or lamellar Schwann cells. The axon terminals of the periodontal Ruffini endings have finger-like projections called axonal spines or microspikes, which extend into the surrounding tissue to detect the deformation of collagen fibers. The functional basis of the periodontal Ruffini endings has been analyzed by histochemical techniques. Histochemically, the axon terminals are reactive for cytochrome oxidase activity, and the terminal Schwann cells have both non-specific cholinesterase and acid phosphatase activity. On the other hand, many investigations have suggested that the Ruffini endings have a high potential for neuroplasticity. For example, immunoreactivity for p75-NGFR (low-affinity nerve growth factor receptor) and GAP-43 (growth-associated protein-43), both of which play important roles in nerve regeneration/development processes, have been reported in the periodontal Ruffini endings, even in adult animals (though these proteins are usually repressed or down-regulated in mature neurons). Furthermore, in experimental studies on nerve injury to the inferior alveolar nerve, the degeneration of Ruffini endings takes place immediately after nerve injury, with regeneration beginning from 3 to 5 days later, and the distribution and terminal morphology returning to almost normal at around 14 days. During regeneration, some regenerating Ruffini endings expressed neuropeptide Y, which is rarely observed in normal animals. On the other hand, the periodontal Ruffini endings show stage-specific configurations which are closely related to tooth eruption and the addition of occlusal forces to the tooth during postnatal development, suggesting that mechanical stimuli due to tooth eruption and occlusion are a prerequisite for the differentiation and maturation of the periodontal Ruffini endings. Further investigations are needed to clarify the involvement of growth factors in the molecular mechanisms of the development and regeneration processes of the Ruffini endings.

Role of cholinergic receptors and cholinesterase activity in hemodynamic responses to cocaine in conscious rats

It has been suggested that toxicity to cocaine is related to the relative rate of cocaine metabolism by cholinesterases and to activation of cholinergic receptors either directly or by reflex mechanisms. We examined these possibilities by altering cholinesterase activity and blocking cholinergic receptors in rats prone or resistant to cocaine-induced cardiovascular toxicity. Rats were instrumented with a pulsed Doppler flow probe on the ascending aorta for measurement of cardiac output and cannulated for arterial pressure and heart rate determination. In conscious rats, cocaine (5 mg/kg iv) elicited pressor responses and a delayed bradycardia but cardiac output and systemic vascular resistance responses varied greatly between rats. Pretreatment with the nonspecific cholinesterase inhibitors physostigmine (0.1-0.2 mg/kg) or neostigmine (0.1 mg/kg) reduced the pressor response by diminishing the increase in systemic vascular resistance. In contrast, inhibition of cocaine metabolism with the selective plasma cholinesterase inhibitor tetraisopropyl pyrophosphoramide (0.5 mg/kg) or increasing cholinesterase activity with human butyryl cholinesterase (9.9 mg/kg iv) did not alter hemodynamic responses to cocaine. Administration of atropine methyl bromide (0.5-1 mg/kg iv) alone or with physostigmine to prevent the cholinomimetic effects of physostigmine reduced the cocaine-induced decrease in cardiac output noted in some animals. These data suggest that the cocaine-induced decrease in cardiac output observed in some rats is, at least in part, dependent on activation of muscarinic receptors. In addition, the rate of cocaine metabolism is not critical for the initial hemodynamic responses to cocaine in conscious rats.