Related Experiment Video
Updated: Jun 2, 2026
11:53
Intracellular Recording, Sensory Field Mapping, and Culturing Identified Neurons in the Leech, Hirudo medicinalis
Published on: November 4, 2013
Serotonin modulates muscle function in the medicinal leech Hirudo verbana
Shannon P Gerry1, David J Ellerby
1Department of Biological Sciences, Wellesley College, Wellesley, MA 02481, USA. sgerry@wellesley.edu
Biology Letters
|May 13, 2011
Summary
Serotonin (5-HT) enhances leech muscle force production across a wide length range, improving locomotion and feeding. This neurotransmitter increases active stress and reduces passive tonus in leech muscles.
Area of Science:
- * Zoology
- * Muscle Physiology
- * Neurobiology
Background:
- * Leech body wall muscles enable diverse behaviors like feeding, crawling, and swimming.
- * These muscles operate over a broad length range, posing challenges for force generation.
- * Serotonin (5-HT) is known to influence leech behavior and passive muscle properties.
Purpose of the Study:
- * To investigate the effect of serotonin (5-HT) on the length-tension relationship (LTR) of leech longitudinal muscles.
- * To determine if 5-HT facilitates force production in elongated leech muscles.
Main Methods:
- * Longitudinal muscle strips from leeches were isolated and studied in vitro.
- * Length-tension relationships (LTRs) were measured in physiological saline.
- * Experiments were conducted with and without the addition of 10 µM 5-HT.
Main Results:
- * The measured LTR for leech muscle was broader than previously reported.
- * 5-HT significantly reduced passive muscle tonus.
- * 5-HT increased active stress generation across all measured muscle lengths.
Conclusions:
- * Serotonin (5-HT) broadens the leech muscle length-tension relationship, enabling force production over a larger range.
- * 5-HT enhances active stress and reduces passive resistance in leech muscles.
- * The findings suggest 5-HT plays a crucial role in optimizing muscle function for locomotion and feeding in leeches.
Related Concept Videos
01:23Drugs Affecting GI Tract Motility: Serotonin Receptor Agonists
Serotonin, a crucial neurotransmitter synthesized by enterochromaffin cells, plays a cardinal role in regulating gastrointestinal (GI) motility. With over 90% of the body's total serotonin in the GI tract, its influence on digestive processes is profound. Serotonin is swiftly released upon various stimuli, such as food boluses or certain drugs, triggering intrinsic sensory neurons in the myenteric plexus and extrinsic vagal and spinal sensory neurons. This leads to the activation of the...
01:28Classification of Skeletal Muscle Relaxants
Skeletal muscle relaxants are a group of drugs that can reduce muscle stiffness and induce temporary paralysis to relieve pain. These agents can act centrally to reduce muscle tone or spasms in painful conditions such as multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), or spinal injuries; they are called antispasmodics or spasmolytics.
Peripherally acting skeletal muscle relaxants interfere with the neurotransmission at the neuromuscular end plate to induce paralysis during...
Peripherally acting skeletal muscle relaxants interfere with the neurotransmission at the neuromuscular end plate to induce paralysis during...
01:26Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin
Directly acting muscle relaxants like dantrolene and botulinum toxin (BoNT) have distinct mechanisms and applications. Dantrolene, a hydantoin derivative, acts on the ryanodine receptor (RYR1) in skeletal muscle cells. RYR1 are calcium channels present at the sarcoplasmic reticulum membrane. In response to excitation, they release calcium ions from the sarcoplasmic reticulum to the cytosol. Calcium promotes actin-myosin-mediated contraction of muscles.
The binding of dantrolene to the RYR1...
The binding of dantrolene to the RYR1...
01:09Peripherally and Centrally Acting Muscle Relaxants: A Comparison
Skeletal muscle relaxants can target the central nervous system [CNS] to reduce muscle tension or act directly at the neuromuscular junction to induce temporary paralysis. These two classes of muscle relaxants are called centrally acting muscle relaxants and peripherally acting muscle relaxants. They differ in their action, mechanism, administration route, and clinical uses.
Centrally acting muscle relaxants can be further divided into spasmolytic and antispasmodic drugs. Spasmolytic drugs,...
Centrally acting muscle relaxants can be further divided into spasmolytic and antispasmodic drugs. Spasmolytic drugs,...
01:31Skeletal Muscle Relaxants: Therapeutic Uses
Skeletal muscle relaxants are used to relax muscle tone and alleviate painful muscle contractions. However, the choice of skeletal muscle relaxants depends on the duration of the surgical procedure in order to minimize potential side effects. Skeletal muscle relaxants like neuromuscular blocking agents [NMBAs] are commonly employed as adjuvants alongside general anesthetics in clinical settings. NMBAs are also used to maintain controlled ventilation during surgery of the larynx or pharynx as...
01:24Centrally Acting Muscle Relaxants: Therapeutic Uses
Centrally acting muscle relaxants reduce muscle tone and tension by interfering with the postsynaptic reflexes in the central nervous system.
Centrally acting drugs are classified into spasmolytic and antispasmodic drugs. Spasmolytic drugs such as baclofen, diazepam, and tizanidine inhibit spinal motor neurons and decrease muscle tone. Spasmolytic drugs are administered for severe and chronic spasms due to multiple sclerosis, cerebral palsy, stroke, and spinal cord and muscle injuries. However,...
Centrally acting drugs are classified into spasmolytic and antispasmodic drugs. Spasmolytic drugs such as baclofen, diazepam, and tizanidine inhibit spinal motor neurons and decrease muscle tone. Spasmolytic drugs are administered for severe and chronic spasms due to multiple sclerosis, cerebral palsy, stroke, and spinal cord and muscle injuries. However,...