Pharyngeal Contraction Research Articles

Gender differences in proximal esophageal contractions

There are reports showing that gender has an influence on swallowing and on the contractions of the distal esophageal body. In this investigation we studied the effect of gender on proximal esophageal contraction. We studied 20 men (22-68 years old, median 39 years) and 44 women (18-61 years old, median 41 years) without symptoms and without gastrointestinal or respiratory diseases. We measured the time interval between the onset of pharyngeal contraction 1 cm proximal to the upper esophageal sphincter and the onset of the proximal esophageal contraction 5 cm from the pharyngeal recording. We also measured the amplitude, duration and area under the curve of the proximal esophageal contractions. The recording was performed by the manometric method with continuous perfusion. The contractions were recorded in duplicate after swallows of a 5 mL bolus of water. There were no differences between men and women in the interval between the onset of pharyngeal and of esophageal contractions or in the amplitude of esophageal contractions. The duration of contractions was longer in women (2.35 +/- 0.60 s) than in men (2.07 +/- 0.62 s) but the difference did not reach statistical significance (P = 0.087). The area under the curve of the esophageal contraction was higher in women (130.2 +/- 55.2 mm Hg x s) than in men (97.4 +/- 49.4 mm Hg x s, P = 0.026). We conclude that there is a difference between men and women in the proximal esophageal contractions in response to wet swallows, although this difference is of no clinical relevance.

Laryngopharyngeal sensory deficits and impaired pharyngeal motor function predict aspiration in patients irradiated for nasopharyngeal carcinoma

To assess the contribution of laryngopharyngeal sensory deficits and impaired pharyngeal motor function to aspiration in patients irradiated for nasopharyngeal carcinoma. A retrospective study at a tertiary referral university teaching hospital. One hundred consecutive patients who underwent radiotherapy for nasopharyngeal carcinoma referred to a dysphagia clinic underwent sensory testing of their laryngopharynx and endoscopic evaluation of their swallowing. The sensory threshold of the laryngopharynx was determined, the pharyngeal contraction assessed, and the status of the larynx and hypopharynx documented before and after swallowing. The presence of laryngeal penetration and aspiration was noted. The average time from radiation therapy to assessment was 10.2 years, and the mean duration of swallowing symptoms was 27 months. Laryngopharyngeal sensation was deficient in 89% of patients and the pharyngeal contraction impaired in 93% patients. Laryngeal penetration and aspiration occurred in 87% and 74% of patients, respectively. Aspiration was associated with food residue in the pyriform fossae after swallowing (P < .001) and impaired pharyngeal contraction (P < .001), but not with laryngopharyngeal sensory deficiency. There was no association between a laryngopharyngeal sensory deficit and impaired pharyngeal contraction. Impaired pharyngeal contraction and food bolus clearance from the hypopharynx during swallowing are more important than laryngopharyngeal sensory deficiency in predicting aspiration in patients who underwent radiotherapy for nasopharyngeal carcinoma.

Reduced expression of voltage-gated chloride channel genes in Caenorhabditis elegans: Implications for the mode of action of chloride channel-directed nematicides

Caenorhabditis elegans nematodes (fourth-stage larvae) were exposed for 24 h to long (4 μg/μl) or short (5 μg/μl) double-stranded RNA (dsRNA) of two voltage-gated chloride channel (VGCC) genes, ceclc-1 and ceclc-2, coding for two VGCC proteins, CeClC-1 and CeClC-2. The treatments reduced expression of these genes in F 1 progeny in a time- and concentration-dependent manner. Progeny with reduced expression of ceclc-2 (but not ceclc-1) showed significant phenotypic effects, such as increased pharyngeal contractions and decreased locomotion, which were maximal in 48 h old worms. Generally, there was little effect on the worms when expression of ceclc-1 alone was reduced. F 1 progeny with reduced expression of both ceclc-1 and ceclc-2 had a higher percentage showing affected locomotion than were present with reduced expression of ceclc-2 alone, whereas the increase in frequency of pharyngeal contractions was not different from that obtained with reduced expression of ceclc-2 alone. These phenotypic effects were consistent with the known expression patterns of ceclc-1 and ceclc-2 in C. elegans tissues. A strong negative correlation was observed between in vitro concentration of long dsRNA and ceclc-2 expression level, as well as between ceclc-2 expression level and corresponding phenotypic effects. The effects of dsRNA exposure are similar to previous studies in which 24-h incubation in 50 ppm of anion transporter (AT) blockers DIDS, 9-AC, IAA-94, or NPPB increased pharyngeal contractions and the proportion of nematodes exhibiting impaired locomotion. These findings confirm that the principal mechanism of nematicidal activity of AT blockers may arise from the inhibition of CeClC-2.

Swallowing Disturbance Pattern Relates to Brain Lesion Location in Acute Stroke Patients

The relationship of brain lesion location and swallowing disturbance pattern has been poorly studied in acute stroke patients. Sixty patients with first-ever acute ischemic stroke at clearly assessed location and clinical signs of dysphagia were studied. Swallowing-related parameters rated clinically and fiberendoscopically were attention deficit, buccofacial apraxia, orofacial paresis, gag reflex, delay of pharyngeal swallow, pharyngeal contraction, larynx elevation, function of upper esophageal sphincter (UES), and aspiration severity. Attention deficit was independently predicted only by parietotemporal infarction, buccofacial apraxia by left-sided parietotemporal infarction, orofacial paresis by infarction encompassing upper motor neuron of cranial nerves, and impaired UES opening by lateral medullary infarction. Other swallowing parameters were not related to lesion topology. On posthoc analysis, pneumonia within 21 days after stroke was predicted only by insular lesion. Distinct acute brain lesion locations result in characteristic swallowing disturbance patterns. Dysphagic patients with insular stroke appear to have even higher risk of pneumonia suggesting a further associated factor promoting infection in these subjects.

Facioscapulohumeral Muscular Dystrophy: A Radiologic and Manometric Study of the Pharynx and Esophagus

Facioscapulohumeral muscular dystrophy (FSHD) is not a recognized neuromuscular cause of dysphagia. However, a study of pharyngoesophageal function in FSHD has not been performed or reported. The aim of this study was to ascertain by relatively noninvasive techniques whether the dystrophic muscle disease that underlies FSHD involves the pharyngeal and/or the esophageal striated and smooth muscles. We used conventional cineradiography and intraluminal esophageal manometry on separate occasions to study pharyngeal and esophageal function in 20 patients with FSHD at various stages of disease, with or without complaints of deglutition. Age- and sex-matched control data were used for comparison of the manometric component of the study. Twelve men and eight women with FSHD were studied. The mean patient age was 38.1 years (41.9 years for controls), and the age range was 19-61 years (22-55 years for controls). The mean disease duration was 16.7 years (range = 4-39 years).Five patients admitted to having intermittent oropharyngeal dysphagia (difficulty to initiate swallowing, cough after swallowing, sensation of food stuck in throat, or nasal regurgitation), and three patients admitted to intermittent esophageal dysphagia (difficulty swallowing both liquids and solids). Chest roentgengrams showed a hiatal hernia in four patients, but no active cardiopulmonary disease. Abnormal instrumental results were documented in eight patients: Cineradiography detected ineffectual pharyngeal contractions (2 patients), pharyngeal diverticula but normal pharyngeal motility (2 patients), and decreased cricopharyngeal and upper esophageal relaxation (2 patients). The mean manometric pressure of the patient group was not significantly different from the control data. However, manometry detected motility abnormalities that were not reflected in the mean data and included increased lower esophageal sphincter resting pressure with normal or abnormal relaxation (2 patients) and inconsistent, high-amplitude, long-duration, primary peristaltic contractions (1 patient). Patients with FSHD did not spontaneously volunteer intermittent complaints of deglutition. This study did not definitely establish that the cause of abnormal pharyngeal and cervical esophageal function was related to the dystrophic process that underlies FSHD. Any esophageal dysmotility was nonspecific and insignificant and was caused by an undetermined, probably neuropathic, process unrelated to the muscular dystrophy.

Long-lasting effect of a single botulinum toxin injection in the treatment of oropharyngeal dysphagia secondary to upper esophageal sphincter dysfunction: A pilot study

Objective. To evaluate the efficacy of botulinum toxin (BTX-A) injection in the cricopharyngeus muscle in patients with neurological dysphagia caused by alteration in the upper esophageal sphincter (UES) opening and with preserved pharyngeal contraction. Material and methods. A prospective pilot study was undertaken in 10 patients (7 brain lesions and 3 cervical spinal cord injuries), with a minimum time-lapse of 6 months from neurological lesion to BTX-A injection. Dysfunction of the UES opening and the presence of pharyngeal contraction were diagnosed by videofluoroscopy (VDF) and esophageal manometry (EM). The BTX-A (100 U) injection was guided by endoscopy. Clinical, VDF, and EM follow-ups were carried out at 3 weeks, 3 and 6 months, and at 1 year post-injection. Results. Prior to treatment, 6 patients were fed by nasogastric tube. VDF showed impairment of the UES opening, residue in pyriform sinuses, and aspiration in all cases. During follow-up, there was a decrease in the number of patients that had aspiration: 3 patients at one year. During swallowing, EM showed a mean UES relaxation of 90% (range: 74.5–100%), residual pressure 3.2 mmHg (range: 0–13 mmHg) and pharyngeal amplitude 52 mmHg (range: 25–80 mmHg). At follow-up, a significant improvement in UES relaxation (98% (89–100%)) and pharyngeal contraction (97 mmHg (35–165 mmHg)) was observed. At 3 months, 6 patients were eating exclusively by mouth. Conclusions. One single injection of BTX-A in the UES has long-lasting effectiveness in patients with neurological dysphagia caused by alteration in the UES opening and with pharyngeal contraction. Nevertheless, a randomized control trial should be done to confirm these results and rule out the effect of potential spontaneous improvement of neurological injury.

Videomanometric Evaluation of Pharyngo‐oesophageal Dysmotility in Children With Velocardiofacial Syndrome

Videomanometric Evaluation of Pharyngo‐oesophageal Dysmotility in Children With Velocardiofacial Syndrome

Unilateral associated laryngeal paralysis due to varicella-zoster virus: virus antibody testing and videofluoroscopic findings

The relationship between varicella-zoster virus and idiopathic associated laryngeal paralysis was examined in five patients, using complement fixation or enzyme immunoassay testing. In all cases, significant changes in serum levels of varicella-zoster virus antibody were observed. Videofluoroscopy was useful in assessing the severity of the dysphagia and in making an accurate diagnosis; both laryngeal elevation and weakness of pharyngeal wall contraction were also observed. In two cases in which antiviral therapy was delayed, the outcome was poor, with increased levels of varicella-zoster virus immunoglobulin M found on enzyme immunoassay. The outcome of the condition may thus depend both on the speed of antiviral therapy commencement following onset of symptoms, and on the levels of varicella-zoster virus immunoglobulin M antibody (measured by enzyme immunoassay). Our study suggests that varicella-zoster virus should be considered in the differential diagnosis of patients with idiopathic associated laryngeal paralysis, and rapid antiviral therapy should be initiated when necessary.

Endogenous Motor Neuron Properties Contribute to a Program-Specific Phase of Activity in the Multifunctional Feeding Central Pattern Generator ofAplysia

Multifunctional central pattern generators (CPGs) are circuits of neurons that can generate manifold actions from a single effector system. This study examined a bilateral pair of pharyngeal motor neurons, designated B67, that participate in the multifunctional feeding network of Aplysia californica. Fictive buccal motor programs (BMPs) were elicited with four distinct stimulus paradigms to assess the activity of B67 during ingestive versus egestive patterns. In both classes of programs, B67 fired during the phase of radula protraction and received a potent inhibitory postsynaptic potential (IPSP) during fictive radula retraction. When programs were ingestive, the retraction phase IPSP exhibited a depolarizing sag and was followed by a postinhibitory rebound (PIR) that could generate a postretraction phase of impulse activity. When programs were egestive, the depolarizing sag potential and PIR were both diminished or were not present. Examination of the membrane properties of B67 disclosed a cesium-sensitive depolarizing sag, a corresponding I(h)-like current, and PIR in its responses to hyperpolarizing pulses. Direct IPSPs originating from the influential CPG retraction phase interneuron B64 were also found to activate the sag potential and PIR of B67. Dopamine, a modulator that can promote ingestive behavior in this system, enhanced the sag potential, I(h)-like current, and PIR of B67. Finally, a pharyngeal muscle contraction followed the radula retraction phase of ingestive, but not egestive motor patterns. It is proposed that regulation of the intrinsic properties of this motor neuron can contribute to generating a program-specific phase of motor activity.

Neurologisch bedingte und neuromuskuläre Funktionsstörungen des Pharynx und Ösophagus

Neurologic swallowing disorders are an increasing diagnostic problem in our overaged population. Undiagnosed chronic aspiration pneumonia is the cause of death in 20-40% of all inhabitants of nursing homes. In neurologic diseases of the pharynx, the physiologic interaction of pharyngeal contraction, closure of the pharynx, and esophageal motility are frequently disturbed. This may be due to cortical, bulbar, or cerebellar brain damage of ischemic or traumatic origin. Furthermore diseases or peripheral nerves, muscles, and synapses cause disturbances. The most life-threatening complication of these disturbances is tracheal aspiration, which requires an iso-osmolar contrast medium for imaging studies that cause no or minimal pulmonary problems. Utilizing fast dynamic documentation we can analyze the swallowing act in 35 images within the passage time of 0.7 s. This requires digital frame sequences from 15-50 images/s, which can be provided by DSI or videofluoroscopy. Neurologic and neuromuscular patterns are demonstrated with and without tracheal aspiration. The differentiation of aspiration in a so-called pre-, intra-, and postdeglutitive form is possible. We distinguish four grades of severity of aspiration, which is also of great clinical impact for the differential rehabilitation therapy. The efficiency of the rehabilitation protocol can be assessed by the dynamic swallowing studies.

Effects of three different swallow maneuvers analyzed by videomanometry

To evaluate the manometric effects of three different swallow maneuvers on healthy volunteers. Ten healthy volunteers with no history of swallowing complaints were evaluated with simultaneous videoradiography and pharyngeal manometry (videomanometry). Three different swallow maneuvers were evaluated (supraglottic swallow, super-supraglottic swallow, and Mendelsohn's maneuver) and seven manometric and two videoradiographic variables were analyzed. The supraglottic swallow showed a significantly weaker peak contraction of the upper esophageal sphincter (UES). The super-supraglottic swallow had a significantly higher UES relaxation pressure and the Mendelsohn maneuver a significantly higher UES peak contraction. With the Mendelsohn maneuver, there was also a significantly longer duration of the pharyngeal contraction and a significantly weaker UES peak contraction. Both the super-supraglottic and the Mendelsohn maneuver had a significantly longer bolus transit time. Our study did not show any significant difference in the relaxation duration of any of the swallowing maneuvers compared to a control swallow. With the Mendelsohn maneuver, we found that both the pharyngeal peak contraction and contraction duration were increased, which might result in an improved propulsion of bolus into the esophagus.

The Effect of Nasogastric Tubes on Swallowing Function in Persons With Dysphagia Following Stroke

Wang T-G, Wu M-C, Chang Y-C, Hsiao T-Y, Lien I-N. The effect of nasogastric tubes on swallowing function in persons with dysphagia following stroke. Objective To determine whether the use of a nasogastric tube influences swallowing function in stroke patients with dysphagia. Design Before-after trial. Setting Primary care center. Participants A total of 22 patients with stroke (12 men, 10 women; mean age, 69.7y; range, 19−85y) participated in the study. Time from onset of stroke to time of assessment averaged 20.3 days (range, 14−38d). All participants continued to use a nasogastric tube for nutrition supply and had either minor or no aspiration of barium on videofluoroscopic examination of swallowing (VFES). Intervention The swallowing function was evaluated by VFES with thin and thick bariums (5mL each) as a contrast medium. Main Outcome Measures The oral transit, swallowing trigger, and pharyngeal transit times were measured and compared before and after the removal of the nasogastric tube. The patients were also observed for changes in velopharyngeal closure, pharyngeal contraction, epiglottic tilt, valleculae stasis, pyriform sinus stasis, penetration, and aspiration. Results Transit times were reduced by 0.2 to 0.6 seconds after removal of the nasogastric tube, but the reduction was not statistically significant. These transit times were slightly longer with thick barium than with thin barium, but were without statistical significance. Similarly, most of the patients had no change in nontemporal assessment of swallowing function after the tube was removed. Conclusions The placement of a nasogastric tube did not affect temporal and nontemporal measurement of swallowing in stroke patients with dysphagia with or without minor aspiration.

Differences in response of the proximal esophagus to wet swallows in patients of Chagas’ disease and idiopathic achalasia

Chagas' disease and idiopathic achalasia have similar esophageal manifestations such as absent or incomplete lower esophageal sphincter relaxation and aperistalsis in the esophageal body (alterations seen mainly in the distal esophageal body). Our aim in this paper was to study the response of the proximal esophageal body to wet swallows in patients with Chagas' disease and patients with idiopathic achalasia. We retrospectively analyzed the time interval between the onset of the pharyngeal contractions 1 cm proximal to the upper esophageal sphincter, as well as 5 cm distal to the pharyngeal measurement. Amplitude, duration and area under the curve of contractions in the proximal esophagus were also determined in 42 patients with Chagas' disease (15 with associated esophageal dilatation), 21 patients with idiopathic achalasia (14 with concomitant esophageal dilatation) and 31 control subjects. The time between the onset of pharyngeal and proximal esophageal contractions was longer in patients with Chagas' disease and in those with esophageal dilatation (1.39 +/- 0.16 s) than in control subjects (0.86 +/- 0.04 s, P < 0.01). The amplitude of proximal esophageal contractions was lower in patients with idiopathic achalasia and esophageal dilatation (60.9 +/- 16.3 mmHg) than in control subjects (89.7 +/- 6.9 mmHg, P = 0.06). The authors conclude that in patients with advanced esophageal disease, the proximal esophageal contractions in Chagas' disease have a delayed response to wet swallows when compared with controls, and that the amplitude of proximal esophageal contractions was lower than expected in patients with idiopathic achalasia.

Deglutitive upper esophageal sphincter relaxation: a study of 75 volunteer subjects using solid-state high-resolution manometry

This study aimed to use a novel high-resolution manometry (HRM) system to establish normative values for deglutitive upper esophageal sphincter (UES) relaxation. Seventy-five asymptomatic controls were studied. A solid-state HRM assembly with 36 circumferential sensors spaced 1 cm apart was positioned to record from the hypopharynx to the stomach. Subjects performed ten 5-ml water swallows and one each of 1-, 10-, and 20-ml volume swallows. Pressure profiles across the UES were analyzed using customized computational algorithms that measured 1) the relaxation interval (RI), 2) the median intrabolus pressure (mIBP) during the RI, and 3) the deglutitive sphincter resistance (DSR) defined as mIBP/RI. The automated analysis succeeded in confirming bolus volume modulation of both the RI and the mIBP with the mean RI ranging from 0.32 to 0.50 s and mIBP ranging from 5.93 to 13.80 mmHg for 1- and 20-ml swallows, respectively. DSR was relatively independent of bolus volume. Peak pharyngeal contraction during the return to the resting state postswallow was almost 300 mmHg, again independent of bolus volume. We performed a detailed analysis of deglutitive UES relaxation with a novel HRM system and customized software. The enhanced spatial resolution of HRM allows for the accurate, automated assessment of UES relaxation and intrabolus pressure characteristics, in both cases confirming the volume-dependent effects and absolute values of these parameters previously demonstrated by detailed analysis of concurrent manometry/fluoroscopy data. Normative values were established to aid in future clinical and investigative studies.

Low Conductance Gap Junctions Mediate Specific Electrical Coupling in Body-wall Muscle Cells of Caenorhabditis elegans

Invertebrate innexins and their mammalian homologues, the pannexins, are gap junction proteins. Although a large number of such proteins have been identified, few of the gap junctions that they form have been characterized to provide combined information of biophysical properties, coupling pattern, and molecular compositions. We adapted the dual whole cell voltage clamp technique to in situ analysis of electrical coupling in Caenorhabditis elegans body-wall muscle. We found that body-wall muscle cells were electrically coupled in a highly organized and specific pattern. The coupling was characterized by small (350 pS or less) junctional conductance (G(j)), which showed a bell-shaped relationship with junctional potential (V(j)) but was independent of membrane potential (V(m)). Injection of currents comparable to the junctional current (I(j)) into body-wall muscle cells caused significant depolarization, suggesting important functional relevance. The innexin UNC-9 appeared to be a key component of the gap junctions. Both Myc- and green fluorescent protein-tagged UNC-9 was localized to muscle intercellular junctions. G(j) was greatly inhibited in unc-9(fc16), a putative null mutant. Specific inhibition of UNC-9 function in muscle cells reduced locomotion velocity. Despite UNC-9 expression in both motor neurons and body-wall muscle cells, analyses of miniature and evoked postsynaptic currents in the unc-9 mutant showed normal neuromuscular transmission. These analyses provide a relatively detailed description of innexin-based gap junctions in a native tissue and suggest that innexin-based small conductance gap junctions can play an important role in processes such as locomotion.

Manofluorographic evaluation of swallowing in amyotrophic lateral sclerosis and its relationship with clinical evaluation of swallowing

The aim of this cross-sectional study was, first, to identify swallowing dysfunctions in an ALS population of 40 consecutive patients through combined videofluoroscopy and manometry. Secondly, these objective swallowing data were correlated with the functional feeding status as reported by the patient or family member. Videofluoroscopic evaluation showed dysfunctions in the oral phase of swallowing, pharyngeal initiation and pharyngeal transport. In addition, manometric data revealed low tongue driving forces and pharyngeal contraction amplitudes but normal relaxation of the upper oesophageal sphincter (UES). Aspiration was noted in a not negligible number of 9/40 patients. These objective data were then correlated with the clinical swallowing and feeding status, assessed by means of the ALS Swallowing Severity Scale. Patients receiving scores of 6 or lower on the ALSSSS, report dietary consistency changes but are considered 'safe oral feeders'. Nevertheless, our data revealed that these patients showed significant aspiration during videofluoroscopy. Although not every patient with ALS should be referred routinely for radiographic evaluation of swallowing, our findings suggest referral for a radiological examination as soon as the ALSSSS drops to a score of 6 or lower, to evaluate the presence of (silent) aspiration.

Can we breathe and swallow at the same time?

The article by Samson et al. ([7][1]) in this issue of the Journal of Applied Physiology raises new issues concerning the regulation of nonnutritive swallowing (NNS) and breathing during sleep. The past 10 years have seen a large increase in interest in this field ([2][2], [3][3]). Clearly, NNS is

AGA technical review on the clinical use of esophageal manometry

AGA technical review on the clinical use of esophageal manometry

The role of botulinum toxin injection and upper esophageal sphincter myotomy in treating oropharyngeal dysphagia.

The aims of this study were to assess the efficacy and safety of botulinum toxin (BoTox) injection in the cricopharyngeus muscle (CP) and CP myotomy in patients with oropharyngeal dysphagia (OPD) and to identify factors predicting the outcome of these treatments. The study involved patients with persistent OPD despite 2-6 months of rehabilitation, who all underwent clinical evaluation, esophageal manometry, upper gastrointestinal endoscopy, and videofluoroscopy (VFS). Patients received 5-10 BoTox units injections in the CP, identified by electromyography. Surgical myotomy of the upper esophageal sphincter was performed when dysphagia persisted after two BoTox injections. After treatment, patients were reevaluated with clinical interviews and VFS. The study population included 21 patients (15 mean and 6 women; median age, 68 years), classified into three groups, based on the etiology of their OPD: eight (38%) had central nervous system abnormalities, five (24%) had peripheral nerve disease, and eight (38%) were classified as idiopathic. The median time since the onset of dysphagia was 18 months. Thirteen of 21 patients (62%) needed supplemental/total gastrostomy feeding, and 5 of 21 (24%) had tracheostomy. One patient died, on posttreatment day 7, due to massive aspiration. No other BoTox-related complications were observed. After BoTox injection, dysphagia improved in 9 of 21 (43%) patients. Severely altered VFS findings and CP incoordination or low activity predicted BoTox failure at multivariate analysis. Dysphagia improved in 8 of 11 (72.7%) patients who failed to respond to BoTox and underwent myotomy. A mild impairment of VFS findings and a higher pressure of pharyngeal contractions best predicted response to BoTox with or without myotomy. BoTox injection can be used as the first therapeutic option in patients with OPD: it is safe and simple and relieves dysphagia in 43% of cases. If BoTox fails, CP myotomy can be offered to patients with preserved oral and tongue activity at VFS and an intact bolus propulsion ability on manometry.

Biogenic amine receptors in parasitic nematodes: what can be learned from Caenorhabditis elegans?

The biogenic amines, serotonin, octopamine, tyramine and dopamine regulate many essential processes in parasitic nematodes, such as pharyngeal pumping, muscle contraction, and egg-laying, as well as more complex behaviors, such as mechanosensation and foraging, making biogenic amine receptors excellent targets for drug discovery. This review is designed to summarize our knowledge of nematode biogenic amine signaling and preliminarily identify some of the key receptors involved in the regulation of biogenic amine-dependent behaviors through an analysis of the free-living nematode, Caenorhabditis elegans.