Effects of orthodontic force on methionine enkephalin and substance P concentrations in human pulpal tissue

Immune System Acts on Orthodontic Tooth Movement: Cellular and Molecular Mechanisms

Orthodontic tooth movement (OTM) is a tissue remodeling process based on orthodontic force loading. Compressed periodontal tissues have a complicated aseptic inflammatory cascade, which are considered the initial factor of alveolar bone remodeling. Since skeletal and immune systems shared a wide variety of molecules, osteoimmunology has been generally accepted as an interdisciplinary field to investigate their interactions. Unsurprisingly, OTM is considered a good mirror of osteoimmunology since it involves immune reaction and bone remolding. In fact, besides bone remodeling, OTM involves cementum resorption, soft tissue remodeling, orthodontic pain, and relapse, all correlated with immune cells and/or immunologically active substance. The aim of this paper is to review the interaction of immune system with orthodontic tooth movement, which helps gain insights into mechanisms of OTM and search novel method to short treatment period and control complications.

Effect of orthodontic force on dental pulp histomorphology and tissue factor expression

OBJECTIVES

To evaluate the effects of orthodontic force on histomorphology and tissue factor expression in the dental pulp.

MATERIALS AND METHODS

Two reviewers comprehensively and systematically searched the literature in the following databases: Latin American and Caribbean Health Sciences, Embase, Cochrane, PubMed, Scopus, Web of Science, and Grey literature (Google Scholar, OpenGrey, and ProQuest) up to September 2020. According to the Population, Intervention, Comparison, Outcomes, Studies criteria, randomized clinical trials (RCTs) and observational studies that evaluated the effects of orthodontic force on dental pulp were included. Case series/reports, laboratory-based or animal studies, reviews, and studies that did not investigate the association between orthodontic force and pulpal changes were excluded. Newcastle-Ottawa Scale and Cochrane risk-of-bias tool were used to assess the risk of bias. The overall certainty level was evaluated with the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

26 observational studies and five RCTs were included. A detailed qualitative analysis of articles showed a wide range of samples and applied methodologies concerning impact of orthodontic force on the dental pulp. The application of orthodontic force seems to promote several pulpal histomorphological changes, including tissue architecture, cell pattern, angiogenesis, hard tissue deposition, inflammation, and alteration of the expression levels of 14 tissue factors.

CONCLUSIONS

Although the included articles suggest that orthodontic forces may promote histomorphological changes in the dental pulp, due to the very low-level of evidence obtained, there could be no well-supported conclusion that these effects are actually due to orthodontic movement. Further studies with larger samples and improved methods are needed to support more robust conclusions.

Pulp sensitivity changes during orthodontic treatment at different time periods: a prospective study

Objective

The purpose of this investigation was to recognize pulp sensitivity changes in teeth receiving orthodontic treatment by means of an electric pulp tester (Vitality Scanner Model 2006; Kerr Corporation, Brea CA, USA).

Materials and methods

An electric stimulus response threshold of eight teeth in 22 patients was measured prior to positioning orthodontic attachments, immediately before ligation of a nickel titanium archwire, immediately after ligation of a stainless steel archwire and 9 to 15 months after having achieved the clinical purposes established with the nickel titanium archwires. The first measurement served as baseline.

Results

All teeth responded to an electrical stimulus at all times. No statistical differences were observed between the response thresholds obtained at different treatment times. The mean response threshold of the second measurement showed a decreasing response threshold tendency when compared with those of the baseline measurement. The mean response threshold of the third measurement showed an increasing tendency when compared with those of the baseline measurement. The first maxillary incisor and canine showed the lowest decreasing response threshold after the second measurement and the highest increasing response threshold after the third measurement. Less noticeable, but similar decreasing and increasing response threshold tendencies were observed in all other teeth after the second and third measurements, respectively.

Conclusions

The results obtained in this investigation suggest that pulp sensitivity can be monitored during orthodontic treatment by means of an electric pulp tester.

Clinical relevance

The importance of monitoring the pulp status during orthodontic treatment.

Influence of orthodontic forces on human dental pulp: a systematic review

AIM

The aim of the present study was to systematically review the influence of orthodontic force on human dental pulp.

METHODS AND RESULTS

The addressed focused question was "Do orthodontic forces affect the human dental pulp?" which was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a specific question was constructed according to the PICO (Participants, Interventions, Control, Outcomes) principle. Databases were explored from 1952 up to and including August 2014 using different combinations of the following keywords: "orthodontic force"; "dental pulp"; "reaction" and "tooth movement". Literature reviews, letters to the editor, commentaries and case-reports were excluded. Thirty studies were included. Six studies assessed the effect of orthodontic forces on pulpal blood flow and 20 studies investigated the pulpal cellular responses to orthodontic forces. In 4 studies, pulpal responses to orthodontic forces were compared between previously traumatized- and non-traumatized teeth.

CONCLUSIONS

There is insufficient scientific validation regarding the association between orthodontic forces and human dental pulp. However, a history of dental trauma maybe considered a risk factor for loss of pulp vitality during orthodontic treatment.

Expression of substance P, calcitonin gene-related peptide, β-endorphin and methionine-enkephalin in human dental pulp tissue after orthodontic intrusion: A pilot study

Objective:

To determine the levels of two sensory neuropeptides (substance P [SP] and calcitonin gene-related peptide [CGRP]) and two endogenous opioids (methionine-enkephalin [Met-Enk] and β-endorphin [β-End]) in dental pulp tissue samples subjected to controlled orthodontic intrusive forces.

Materials and Methods:

Sixteen healthy premolars were selected from eight patients who were undergoing extraction for orthodontic purposes. Eight were randomly used as controls, and the other eight were assigned to an experimental group (controlled orthodontic intrusive forces applied for 24 hours). After this period, teeth were extracted, and pulp samples were obtained. All samples were processed to quantify the expression levels of SP, CGRP, Met-Enk, and β-End using commercial radioimmunoassay kits.

Results:

All samples exhibited basal levels of both neuropeptides and endogenous opioids. After 24 hours of the intrusive stimulus, all patients reported a tolerable discomfort localized at the involved premolar. Only SP was significantly increased (P < .05). For the other molecules, no statistically significant differences were observed (P > .05); however, they expressed important increasing trends.

Conclusions:

The expression levels of SP and CGRP in dental pulp samples from the experimental group support the positive correlation between the symptomatic clinical scenario and increased expression levels of neuropeptides, clarifying the role of neurogenic inflammation in early injury response.

Effect of low level laser therapy on dental pulp during orthodontic movement

AIM: To validate the protocol described here to be used in future clinical trials related to the effect of laser therapy on dental pulp.

METHODS: Histologically treated samples from eight human healthy premolar teeth obtained from the middle root level were distributed in four groups: group 1 (G1) absolute control; group 2 (G2) only laser irradiation; group 3 (G3) exposed only to orthodontics; and group 4 (G4) treated with orthodontics and laser. Laser treatment was performed at 830 nm wavelength, 100 mW (energy 80 J/cm², 2.2 J), for 22 s in the vestibular surface and 22 s in the palatal surface, 1 mm away from the dental root mucosa. Three staining methods were performed: hematoxylin-eosin (HE), Masson’s Trichrome method and Gomori’s method.

RESULTS: The pulp histology parameters were evaluated and the results classified in to 3 parts: an inflammatory response, soft tissue response (dental pulp) and hard tissue response (dentin and predentin). There was no inflammation (chronic or acute) in any of the evaluated groups. The zones of pulp necrosis were found in one premolar of G3 and in one of G4; in groups G2 and G4 there was higher angiogenesis than in the other two groups. G4 group presented the highest level of vascularization. A reduced nerve density was observed in G3. A G2 specimen showed increased nerve density. A higher rate of calcification was observed in G1 compared to G2. Denticles, either real or false, were observed in G1, G2 and G3. Sclerosis of dentin and focal dentin loss was observed among all the groups. Secondary dentin was present in one sample in G1 and G2. A necrosis zone was found in one sample of G3 and G4. No differences between groups were observed in the odontoblast irregularity layer but the layer was wider in the group treated with laser only. A notable difference was detected in reduction of the cell-free layer between the groups G1 and G4. The findings in pulp tissue favor its adaptative response against dental movement induced by orthodontics. No definitive conclusions may be derived as this is a pilot study.

CONCLUSION: The protocol described here was shown to be an effective method to evaluate changes in dental pulp submitted to low level laser in teeth under orthodontic movement.

Prospective randomized clinical trial to compare pain levels associated with 2 orthodontic fixed bracket systems

INTRODUCTION

In this randomized clinical trial, we compared pain levels associated with 2 fixed appliance systems during initial orthodontic tooth movement.

METHODS

Sixty-six patients (36 female, 30 male) were randomly allocated to either a conventional twin bracket (Tru Straight, Ormco Europe, Amersfoort, The Netherlands) or a self-ligating bracket (Damon 3, Ormco). Both arches were bonded, and a 0.014-in superelastic copper-nickel-titanium archwire was ligated in position. Pain intensity levels were recorded twice a day, over 7 days, by using 10-cm visual analog scales. Patients also recorded whether analgesia was taken. Contact point displacements were measured on study models to calculate Little's irregularity index.

RESULTS

Fifty-two patients (78.8%) completed the trial (84.8% in the Tru Straight group and 72.7% in the Damon 3 group). Patients in the Damon 3 group reported lower mean maximum pain intensity (P = 0.053) and significantly lower mean pain intensity (P = 0.012) than did the Tru Straight patients. Patients who consumed analgesics reported significantly higher mean maximum pain intensity and mean pain intensity than those who did not take analgesia (P <0.001). The Damon 3 patients generally reported lower pain intensity than the Tru Straight patients.

CONCLUSIONS

Although there were wide interindividual variations, in this study, the Damon 3 appliance resulted in lower pain intensity, on average, when compared with the Tru Straight appliance.

Local Opioids in the Inflamed Dental Pulp

We have looked for the presence of beta-endorphin and somatostatin in normal and inflamed pulps. In 25 adult rats, under anesthesia, small openings were made into the pulp on the mesial surface of both first molars on one side. One week later all four first molars were removed, half were processed for immunohistochemistry using specific antibodies to beta-endorphin, somatostatin, and CD3, a marker for T lymphocytes. The pulps of the remainder were removed, solubilized, and subjected to enzyme-linked immunosorbent assay for somatostatin and beta-endorphin. Many cells that labeled for beta-endorphin and somatostatin in the injured pulps also stained for CD3. The levels of both beta-endorphin and somatostatin, were higher in the exposed than in the uninjured pulps (t test, p < 0.05). beta-endorphin and somatostatin are both produced in increased amounts in the dental pulp during inflammation attributable, at least in part, to the presence of T lymphocytes producing these substances.

A longitudinal evaluation of pulpal pain during orthodontic tooth movement

OBJECTIVES

To examine the longitudinal changes in pulpal sensitivity to electrical stimulation and the relationship to pulpal sensitivity as measured by electrical stimulation and subjective reports of tooth pain after archwire insertion.

DESIGN

Non-randomized, prospective trial, with matched controls.

SETTING AND SAMPLE POPULATION

Regional Clinical Dental Research Center at the University of Washington School of Dentistry. Eighteen adult subjects of age 13-37 years. Nine experimental subjects planned for orthodontic treatment. Nine control subjects matched for gender and age who did not have orthodontic treatment.

EXPERIMENTAL VARIABLE

Fixed orthodontic appliances and initial archwire placement in experimental subjects compared with 'no treatment' control subjects.

OUTCOME MEASURE

Subjective assessments of orthodontic tooth pain were made using visual analogue scales. Electrically evoked detection and pain thresholds were determined using a computer-controlled tooth stimulator. Data were gathered at five time points: after bracket placement (baseline), 1 h after placement of initial archwires, 1 day after archwire placement, 1 week after archwire placement, and 1 month after archwire placement. Comparable time intervals were used for the 'no treatment' control subjects.

RESULTS

Subjective ratings of treatment-evoked tooth pain in the experimental group were the greatest at the post-archwire day 1 observation and progressively decreased for the remaining observations. Control subjects reported little pain at any of these observation times. The detection and pain threshold changes from baseline showed no statistical differences over time or between groups. While not statistically significant, a trend was noted where reports of greater orthodontic tooth pain were associated with increased sensitivity to electrical stimulation (i.e. lower detection and pain thresholds).

CONCLUSION

Orthodontic patients experience significant pain and discomfort 1 day after initial archwire placement (i.e. activation). Future research should investigate whether self-reports of treatment-evoked tooth pain intensity are associated with pulpal sensitivity.

Quantitative analysis of substance P, neurokinin A and calcitonin gene-related peptide in pulp tissue from painful and healthy human teeth

AIM

The purpose of this study was to investigate the levels of substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) in painful and healthy human dental pulps.

METHODOLOGY

Forty-six samples of pulp tissue were collected from extracted or endodontically treated painful teeth and 20 from clinically healthy teeth extracted for orthodontic reasons. All pulp samples were boiled in 0.5 m acetic acid for 10 min, centrifuged and the supernatant collected. SP, NKA and CGRP levels were measured using radioimmunoassay.

RESULTS

Substance P and CGRP were present in all samples and NKA was detected in 96% of the pulps. CGRP was present in much higher concentrations than SP and NKA in both painful and non-painful teeth. The painful teeth had significantly higher concentrations of SP (P = 0.02), NKA (P < 0.001) and CGRP (P = 0.03) than non-painful teeth. The concentration of CGRP was significantly higher in the pulps of smokers compared with non-smokers (P = 0.02).

CONCLUSIONS

Elevated levels of these neuropeptides in pulps from painful teeth indicate that they may play an important role in the process of pulpal inflammation and pain. Further investigation of the association between these neuropeptides and pulpal status may help to improve our understanding of pulpal inflammation and dental pain.

A comparison of four extraction methods for substance P, neurokinin A and calcitonin gene-related peptide from human dental pulp tissue

Measuring neuropeptides in biological tissues by radioimmunoassay requires efficient extraction that maintains their immunoreactivity. Many different methods for extraction have been described, but there is little information on optimal extraction methods for individual neuropeptides from human dental pulp tissue. The aim was therefore to identify an effective extraction procedure for three pulpal neuropeptides; substance P, neurokinin A and calcitonin gene-related peptide. Tissue was obtained from 20 pulps taken from teeth freshly extracted for orthodontic reasons. The pulp samples were divided into four equal groups and different extraction methods were used for each group. Boiling whole pulp in acetic acid gave the highest overall yield and, in addition, offered an easy and rapid means of pulp tissue processing. The use of protease inhibitors did not increase the recovery of the immunoreactive neuropeptides but did provide the best combination of maximal recoveries and minimal variability. These results should be useful for planning the extraction of these neuropeptides from human pulp tissue in future studies.

Endodontic-orthodontic relationships: a review of integrated treatment planning challenges

Literature review There is a paucity of information on the concise relationship between endodontics and orthodontics during treatment planning decisions. This relationship ranges from effects on the pulp from orthodontic treatment and the potential for resorption during tooth movement, to the clinical management of teeth requiring integrated endodontic and orthodontic treatment. This paper reviews the literature based on the definition of endodontics and the scope of endodontic practice as they relate to common orthodontic-endodontic treatment planning challenges. Literature data bases were accessed with a focus on orthodontic tooth movement and its impact on the viability of the dental pulp; its impact on root resorption in teeth with vital pulps and teeth with previous root canal treatment; the ability to move orthodontically teeth that were endodontically treated versus nonendodontically treated; the role of previous tooth trauma; the ability to move teeth orthodontically that have been subjected to endodontic surgery; the role of orthodontic treatment in the provision for and prognosis of endodontic treatment; and, the integrated role of orthodontics and endodontics in treatment planning tooth retention. Orthodontic tooth movement can cause degenerative and/or inflammatory responses in the dental pulp of teeth with completed apical formation. The impact of the tooth movement on the pulp is focused primarily on the neurovascular system, in which the release of specific neurotransmitters (neuropeptides) can influence both blood flow and cellular metabolism. The responses induced in these pulps may impact on the initiation and perpetuation of apical root remodelling or resorption during tooth movement. The incidence and severity of these changes may be influenced by previous or ongoing insults to the dental pulp, such as trauma or caries. Pulps in teeth with incomplete apical foramen, whilst not immune to adverse sequelae during tooth movement, have a reduced risk for these responses. Teeth with previous root canal treatment exhibit less propensity for apical root resorption during orthodontic tooth movement. Minimal resorptive/remodelling changes occur apically in teeth that are being moved orthodontically and that are well cleaned, shaped, and three-dimensionally obturated. This outcome would depend on the absence of coronal leakage or other avenues for bacterial ingress. A traumatized tooth can be moved orthodontically with minimal risk of resorption, provided the pulp has not been severely compromised (infected or necrotic). If there is evidence of pulpal demise, appropriate endodontic management is necessary prior to orthodontic treatment. If a previously traumatized tooth exhibits resorption, there is a greater chance that orthodontic tooth movement will enhance the resorptive process. If a tooth has been severely traumatized (intrusive luxation/avulsion) there may be a greater incidence of resorption with tooth movement. This can occur with or without previous endodontic treatment. Very little is known about the ability to move successfully teeth that have undergone periradicular surgical procedures. Likewise, little is known about the potential risks or sequelae involved in moving teeth that have had previous surgical intervention. Especially absent is the long-term prognosis of this type of treatment. During orthodontic tooth movement, the provision of endodontic treatment may be influenced by a number of factors, including but not limited to radiographic interpretation, accuracy of pulp testing, patient signs and symptoms, tooth isolation, access to the root canal, working length determination, and apical position of the canal obturation. Adjunctive orthodontic root extrusion and root separation are essential clinical procedures that will enhance the integrated treatment planning process of tooth retention in endodontic-orthodontic related cases.

Identification of bradykinin, substance P, and neurokinin A in human dental pulp

Methodology was developed that uses reverse phase, high performance liquid chromatography (HPLC) to identify and quantify bradykinin, substance P, and neurokinin A contained in dental pulp tissue. Pulp tissue was prepared and homogenized from teeth frozen in liquid nitrogen, Known amounts of three substances found in inflamed tissue were added to the homogenized tissue and also to bovine serum albumin (BSA) (positive control), and supernatants were analyzed using HPLC. Other pulp tissue was prepared and analyzed without the addition of the substances. Recovery from the pulp and BSA with added substances was similar, with bradykinin recovered maximally. In pulp tissue without additions, all three substances were recovered. Thus HPLC appears to be a viable alternative to other methods for identification of these substances and allows for their quantification.

The effects of orthodontic treatment on isometric bite forces and mandibular motion in patients before orthognathic surgery

PURPOSE

Little is known about the effects of orthodontic treatment on oral motor function. The objective of this report is to evaluate changes in mandibular motion and maximum bite force that occur between the initiation of presurgical orthodontics and its completion before surgery.

PATIENTS AND METHODS

Fifteen patients (9 women, 6 men) with a variety of dentofacial deformities were examined before and after presurgical orthodontics. Mechanical advantage of the muscles and bite points, mandibular range of motion, maximum isometric bite force, and levels of electromyographic (EMG) activity in the anterior and posterior temporalis and masseter muscles during isometric bites were recorded on all subjects over time. Data obtained before and after completion of presurgical orthodontics were statistically compared.

RESULTS

Presurgical orthodontics reduced mandibular mobility somewhat, but the amount was not significant. Statistically significant reductions in bite force were noted after orthodontics for incisor, canine, premolar, and molar bite positions. No significant difference in the EMG/bite force slopes was obtained, nor was there any difference in the moment arms of the bite points or the muscles of mastication from orthodontics.

CONCLUSIONS

This study showed significant changes in measures of oral motor function resulting from orthodontic treatment. A larger study is needed to confirm that these results will be similar in all orthodontic patients. There is no indication that these changes are the result of physiologic alterations of the muscles of mastication. The best current explanation is that these changes result from the pain and discomfort of the orthodontic appliances and the induced malocclusion.

Methionine enkephalin-like, substance P-like, and beta-endorphin-like immunoreactivity in human parotid saliva

These three neuropeptides were measured at daily baseline values by radioimmunoassay. Stimulated parotid saliva was collected from 31 subjects using a modified Carlson-Crittenden device affixed over Stenson's duct. Methionine enkephalin-like immunoreactivity ranged from 6.6 to 11.7 fmol/ml, with a mean of 9.3 fmol/ml. Substance P-like immunoreactivity ranged from 6.1 to 12.6 fmol/ml, with a mean of 9.3 fmol/ml. beta-Endorphin-like immunoreactivity ranged from 1.2 to 3.6 fmol/ml, with a mean of 2.6 fmol/ml. This is believed to be the first documentation of methionine enkephalin- and substance P-like activities in human parotid saliva and the first demonstration of beta-endorphin-like activity in any type of human saliva. Substance P-like activity was significantly higher in morning than evening samples; beta-endorphin-like activity also tended to be higher in the morning samples. Substance P and beta-endorphin-like immunoreactivities covaried in a significant positive manner, suggesting either common control mechanisms or similar responses to physiological variables.

Medication of the dental pulp: a review and proposals

For years, dentists have desired to treat the intact dental pulp. Since it is well-known that many substances, including some drugs, are capable of permeating dentin, we believe it is possible to treat certain types of pulpitis by applying drugs at the base of cavity preparations. Useful drugs include local anesthetics to block pain transmission, glucocorticoids or non-steroidal anti-inflammatory agents (NSAIA) to treat inflammation, NSAIA or narcotic analgesics for pain control, and antibiotics to treat infection. The literature is reviewed and proposals are presented to study medication of the dental pulp.

Substance P immunoreactivity in periodontal tissues during orthodontic tooth movement

Neurotransmitters, such as substance P (SP), may mediate the biological response to mechanical stress applied to teeth during orthodontic treatment. This hypothesis was investigated immunohistochemically on maxillae of cats which had one maxillary canine tipped distally for a period of time ranging from 1 h to 14 days. Horizontal histological sections 5 microns thick, collected on adhesive tape while still frozen, then freeze-dried, were stained by an immunoglobulin-enzyme bridge method using rabbit anti-SP polyclonal antibodies. The specificity of the staining was evaluated either by using the serum of non-immunized rabbits in lieu of anti-SP serum, or by pre-incubating the anti-SP serum with the antigen. Only sparse SP-like immunoreactivity was detected in the dental pulp, near or in the walls of blood vessels, or in the periodontal ligament (PDL) of unstressed canines. However, the density of neuronal elements exhibiting positive staining for SP appeared to increase markedly after application of an orthodontic force. This phenomenon occurred rapidly (3 h) in the dental pulp, but later in the PDL (24 h to 14 days), mainly at compression sites. These results demonstrate that the stimulation of periodontal nerve terminals by means of orthodontic forces may induce the peripheral release of the neurotransmitter SP, suggesting that it may be an initial trigger for a biochemical cascade which comprises the activation of various types of PDL cells.

Proenkephalin A and proopiomelanocortin peptides in human cerebrospinal fluid

Precursors to beta-endorphin (BE) and methionine enkephalin (ME), and proteolytic enzymes that cleave those BE and ME precursors to BE and ME, were determined in several milliliters of human cerebrospinal fluid. Endogenous peptides were purified by reversed-phase high-performance liquid chromatography (HPLC), and were detected with radioreceptor assay (RRA), radioimmunoassay, and mass spectrometry (MS). Total opioid receptor activity measurements and the profile of HPLC-receptor activity of human CSF samples were both used to monitor neuropeptide metabolism. MS data linked the molecular ion of ME to a unique fragment ion. A later-eluting fraction (84 min) in a 90-min HPLC gradient appeared in all HPLC-RRA profiles, contained opioid receptor activity that displaced [3H]etorphine, and the quantitative and qualitative patterns of opioid receptor activity in those profiles both changed within the few minutes that elapsed between acquiring the first and second cerebrospinal fluid samples. That 84-min fraction contained precursors to opioid peptides and was fractionated further with a more shallow 120-min HPLC gradient into three sections that displayed delta-opioid receptor-preferring activity, using [3H]ME as ligand. These three sections were hydrolyzed separately with human cerebrospinal fluid as the source for endogenous neuropeptides to yield products that correlated to immunoreactive BE in section I and immunoreactive ME in section III.

Opioid and tachykinin peptides, and their precursors and precursor-processing enzymes, in human cerebrospinal fluid

Opioid and tachykinin neuropeptides, which were derived from two biological sources (intact, and released from their corresponding precursors by the action of human cerebrospinal fluid (CSF) neuropeptidases), were characterized in human CSF by using a combination of post-high-performance liquid chromatographic (HPLC) detection techniques. Peptides were separated using gradient and isocratic reversed-phase HPLC. Radioimmunoassay measured immunoreactivity corresponding to several different individual neuropeptides including methionine enkephalin, leucine enkephalin, substance P and beta-endorphin. Commercial enzymes (trypsin, carboxypeptidase B) were used to release methionine- and leucine-enkephalin from precursors. Human CSF also served as a source of endogenous neuropeptidases. Mass spectrometry produced fragment ions that corroborated the amino acid sequence of methionine enkephalin and of substance P derived from both sources (intact, from precursors). These results demonstrated the presence of endogenous intact neuropeptides, several different neuropeptide-containing precursors and appropriate precursor-processing enzymes in human CSF for precursors of methionine enkephalin, leucine enkephalin, beta-endorphin1-31 and substance P.