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Serotonin leech

Yanqing Wang, Brian D Burrell
Endocannabinoids, such as 2-arachidonoyl glycerol (2-AG) and anandamide, can elicit long-term depression of both excitatory and inhibitory synapses. This latter effect will result in disinhibition and would therefore be expected to produce an increase in neural circuit output. However, there have been no examples directly linking endocannabinoid-mediated disinhibition to a change in a functional neurobehavioral circuit. The present study uses the well-characterized central nervous system of the medicinal leech, Hirudo verbana, to examine the functional/behavioral relevance of endocannabinoid modulation of an identified afferent synapse...
February 1, 2018: Journal of Neurophysiology
Robin L Carhart-Harris, Leor Roseman, Mark Bolstridge, Lysia Demetriou, J Nienke Pannekoek, Matthew B Wall, Mark Tanner, Mendel Kaelen, John McGonigle, Kevin Murphy, Robert Leech, H Valerie Curran, David J Nutt
Psilocybin with psychological support is showing promise as a treatment model in psychiatry but its therapeutic mechanisms are poorly understood. Here, cerebral blood flow (CBF) and blood oxygen-level dependent (BOLD) resting-state functional connectivity (RSFC) were measured with functional magnetic resonance imaging (fMRI) before and after treatment with psilocybin (serotonin agonist) for treatment-resistant depression (TRD). Quality pre and post treatment fMRI data were collected from 16 of 19 patients. Decreased depressive symptoms were observed in all 19 patients at 1-week post-treatment and 47% met criteria for response at 5 weeks...
October 13, 2017: Scientific Reports
Enzo Tagliazucchi, Leor Roseman, Mendel Kaelen, Csaba Orban, Suresh D Muthukumaraswamy, Kevin Murphy, Helmut Laufs, Robert Leech, John McGonigle, Nicolas Crossley, Edward Bullmore, Tim Williams, Mark Bolstridge, Amanda Feilding, David J Nutt, Robin Carhart-Harris
Lysergic acid diethylamide (LSD) is a non-selective serotonin-receptor agonist that was first synthesized in 1938 and identified as (potently) psychoactive in 1943. Psychedelics have been used by indigenous cultures for millennia [1]; however, because of LSD's unique potency and the timing of its discovery (coinciding with a period of major discovery in psychopharmacology), it is generally regarded as the quintessential contemporary psychedelic [2]. LSD has profound modulatory effects on consciousness and was used extensively in psychological research and psychiatric practice in the 1950s and 1960s [3]...
April 25, 2016: Current Biology: CB
Francisco F De-Miguel, Carolina Leon-Pinzon, Paula Noguez, Bruno Mendez
Serotonin, a modulator of multiple functions in the nervous system, is released predominantly extrasynaptically from neuronal cell bodies, axons and dendrites. This paper describes how serotonin is released from cell bodies of Retzius neurons in the central nervous system (CNS) of the leech, and how it affects neighbouring glia and neurons. The large Retzius neurons contain serotonin packed in electrodense vesicles. Electrical stimulation with 10 impulses at 1 Hz fails to evoke exocytosis from the cell body, but the same number of impulses at 20 Hz promotes exocytosis via a multistep process...
July 5, 2015: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Elizabeth Hahn, Brian Burrell
This study examined the capacity of a known pro-epileptic drug, pentylenetetrazol (PTZ), to elicit seizure-like activity in the medicinal leech, Hirudo verbana. During in vivo experiments, PTZ elicited increased motor activity in a concentration-dependent manner with the highest concentration (10 mM) eliciting episodes of highly uncoordinated exploratory and swimming behavior. Co-application of the anti-epileptic drug, phenytoin, failed to reduce the absolute amount of PTZ-induced motor behavior, but was able to prevent expression of abnormal exploratory and swimming behaviors...
2015: Invertebrate Neuroscience: IN
Carolina Leon-Pinzon, Montserrat G Cercós, Paula Noguez, Citlali Trueta, Francisco F De-Miguel
The soma of many neurons releases large amounts of transmitter molecules through an exocytosis process that continues for hundreds of seconds after the end of the triggering stimulus. Transmitters released in this way modulate the activity of neurons, glia and blood vessels over vast volumes of the nervous system. Here we studied how somatic exocytosis is maintained for such long periods in the absence of electrical stimulation and transmembrane Ca(2+) entry. Somatic exocytosis of serotonin from dense core vesicles could be triggered by a train of 10 action potentials at 20 Hz in Retzius neurons of the leech...
2014: Frontiers in Cellular Neuroscience
James D Angstadt, Amanda M Simone
Postinhibitory rebound (PIR) is an intrinsic property often exhibited by neurons involved in generating rhythmic motor behaviors. Cell DE-3, a dorsal excitatory motor neuron in the medicinal leech exhibits PIR responses that persist for several seconds following the offset of hyperpolarizing stimuli and are suppressed in reduced Na(+) solutions or by Ca(2+) channel blockers. The long duration and Na(+) dependence of PIR suggest a possible role for persistent Na(+) current (I NaP). In vertebrate neurons, the neuroprotective agent riluzole can produce a selective block of I NaP...
August 2014: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
Kristan A Leech, Catherine R Kinnaird, T George Hornby
Incomplete spinal cord injury (iSCI) often results in significant motor impairments that lead to decreased functional mobility. Loss of descending serotonergic (5HT) input to spinal circuits is thought to contribute to motor impairments, with enhanced motor function demonstrated through augmentation of 5HT signaling. However, the presence of spastic motor behaviors in SCI is attributed, in part, to changes in spinal 5HT receptors that augment their activity in the absence of 5HT, although data demonstrating motor effects of 5HT agents that deactivate these receptors are conflicting...
August 1, 2014: Journal of Neurotrauma
Majid Moshtagh-Khorasani, Evan W Miller, Vincent Torre
Using the newly developed voltage-sensitive dye VF2.1.Cl, we monitored simultaneously the spontaneous electrical activity of ∼80 neurons in a leech ganglion, representing around 20% of the entire neuronal population. Neurons imaged on the ventral surface of the ganglion either fired spikes regularly at a rate of 1-5 Hz or fired sparse spikes irregularly. In contrast, neurons imaged on the dorsal surface, fired spikes in bursts involving several neurons. The overall degree of correlated electrical activity among leech neurons was limited in control conditions but increased in the presence of the neuromodulator serotonin...
October 2013: Physiological Reports
Giovanna Traina, Chiara Ristori, Marcello Brunelli, Rossana Scuri
Several studies suggest that acetyl-l-carnitine (ALC) might influence learning processes. Along this line of investigation, we have previously shown that ALC impaired sensitization and dishabituation induced by nociceptive stimulation of the dorsal skin of the leech Hirudo medicinalis, in the behavioural paradigm of the swim induction (SI). In previous works we showed that 5HT was involved in both sensitization and dishabituation of SI acting through the second messenger cAMP. In this work, we have reported that for given doses and temporal ranges ALC was able to block sensitization and to impair dishabituation mimicked by the injection of 5-HT or 8Br-cAMP, a membrane permeable analogue of cAMP...
September 15, 2013: Behavioural Brain Research
Francisco F De-Miguel, Iván Santamaría-Holek, Paula Noguez, Carlos Bustos, Enrique Hernández-Lemus, J Miguel Rubí
Transmitter exocytosis from the neuronal soma is evoked by brief trains of high frequency electrical activity and continues for several minutes. Here we studied how active vesicle transport towards the plasma membrane contributes to this slow phenomenon in serotonergic leech Retzius neurons, by combining electron microscopy, the kinetics of exocytosis obtained from FM1-43 dye fluorescence as vesicles fuse with the plasma membrane, and a diffusion equation incorporating the forces of local confinement and molecular motors...
2012: PloS One
Wen-Hui Wu, Robin L Cooper
The serotonergic system in vertebrates and invertebrates has been a focus for over 50 years and will likely continue in the future. Recently, genomic analysis and discovery of alternative splicing and differential expression in tissues have increased the knowledge of serotonin (5-HT) receptor types. Comparative studies can provide useful insights to the wide variety of mechanistic actions of 5-HT responsible for behaviors regulated or modified by 5-HT. To determine cellular responses and influences on neural systems as well as the efferent control of behaviors by the motor units, preparations amenable to detailed studies of synapses are beneficial as working models...
September 2012: Experimental Neurobiology
Shannon P Gerry, Amanda J Daigle, Kara L Feilich, Jessica Liao, Azzara L Oston, David J Ellerby
The obliquely striated muscle in the leech body wall has a broad functional repertoire; it provides power for both locomotion and suction feeding. It also operates over an unusually high strain range, undergoing up to threefold changes in length. Serotonin (5-HT) may support this functional flexibility, integrating behavior and biomechanics. It can act centrally, promoting motor outputs that drive body wall movements, and peripherally, modulating the mechanical properties of body wall muscle. During isometric contractions 5-HT enhances active force production and reduces resting muscle tone...
August 2012: Zoology: Analysis of Complex Systems, ZACS
Citlali Trueta, Damien P Kuffler, Francisco F De-Miguel
We studied the cycling of dense core vesicles producing somatic exocytosis of serotonin. Our experiments were made using electron microscopy and vesicle staining with fluorescent dye FM1-43 in Retzius neurons of the leech, which secrete serotonin from clusters of dense core vesicles in a frequency-dependent manner. Electron micrographs of neurons at rest or after 1 Hz stimulation showed two pools of dense core vesicles. A perinuclear pool near Golgi apparatuses, from which vesicles apparently form, and a peripheral pool with vesicle clusters at a distance from the plasma membrane...
2012: Frontiers in Physiology
Enrique Hernández-Lemus
No abstract text is available yet for this article.
2012: Frontiers in Physiology
Giacomo Bisson, Ginestra Bianconi, Vincent Torre
Leeches exploring a new environment continuously meet each other and merge in temporary groups. After 2-3 h, leeches become attracted to each other eventually forming a large and stable group. When their number is reduced, leeches remain solitary, behaving independently. Group formation is facilitated by body injection of serotonin (5-HT) and the level of endogenous 5-HT is elevated in leeches forming a large group. In contrast, intravenous injection of 5-HT antagonists prevented injected leeches from joining a large group of conspecifics...
2012: Frontiers in Physiology
Rajendra Gharbaran, Gabriel O Aisemberg, Susana Alvarado
Using double immunofluorescence experiments, we described the expression of the leech Hox genes, Lox1 and Lox2 by central neurons that stained for either serotonin or the leech-specific neuronal marker, Laz1-1. The goal is to determine whether the segmental boundaries of Lox1 and Lox2 expression in identified neurons coincide with segmental and regional differences in the differentiation of these cells. A number of neurons described here have been previously identified. The anteromedial serotonergic neurons are restricted to rostral ganglion 1 (R1) to midbody ganglion 3 (M3), but only express Lox1 in M2 and M3...
November 2012: Cellular and Molecular Neurobiology
Rhanor Gillette
Serotonergic systems of invertebrate and vertebrate central nervous systems (CNS) are functionally similar in multiple characters. Serotonin (5-HT) neurons dispersed throughout the CNS of lophotrochozoan invertebrates (molluscs and leeches) are analogous to vertebrate 5-HT neurons concentrated in the raphe nuclei of mid- and hindbrain: they innervate specific central pattern generators and other circuits of the CNS, receive feedback from them, and support general behavioral arousal. In both groups 5-HT regulates excitatory gain of CNS circuitry and uses similarly diverse 5-HT receptors...
December 2006: Integrative and Comparative Biology
Shannon P Gerry, David J Ellerby
The body wall muscles of sanguivorous leeches power mechanically diverse behaviours: suction feeding, crawling and swimming. These require longitudinal muscle to exert force over an extremely large length range, from 145 to 46 per cent of the mean segmental swimming length. Previous data, however, suggest that leech body wall muscle has limited capacity for force production when elongated. Serotonin (5-HT) alters the passive properties of the body wall and stimulates feeding. We hypothesized that 5-HT may also have a role in allowing force production in elongated muscle by changing the shape of the length-tension relationship (LTR)...
December 23, 2011: Biology Letters
Giacomo Bisson, Vincent Torre
In the present study we analyzed the behavior and interactions among leeches in the same observation tank. Colored beads were glued onto their skin so that their behavior could be followed and quantified. When two or three leeches were present in the observation tank, they searched around for a maximum of 2 h and their motion and behavior were independent from those of their conspecifics. When the number of leeches in the tank was increased to 10, leeches were attracted to each other and exhibited episodes of highly correlated behavior...
July 2011: Journal of Neurophysiology
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