Biochemical Localisation of the 5-HT2A(serotonin) Receptor in Rat Skeletal Muscle

doi:10.1006/bbrc.1999.0471

Biochemical and Biophysical Research Communications

Volume 257, Issue 2, 13 April 1999, Pages 369-372

https://doi.org/10.1006/bbrc.1999.0471 Get rights and content

Abstract

The 5-HT_2Areceptor was recently shown to localise morphologically to the transverse tubules (TT) in rat foetal myoblasts. Receptor activation enhanced the expression of genes involved in myogenesis, and its TT localisation has led to the suggestion that it may participate in excitation-contraction coupling. In order to gain further insights into 5-HT_2Areceptor function in muscle we have (i) investigated its biochemical localisation in adult rat skeletal muscle and (ii) determined whether receptor expression is dependent upon muscle type. Immunoblot analysis of muscle membranes, isolated by subcellular fractionation, revealed that adult muscle expresses the 5-HT_2Areceptor and that it resides exclusively in plasma membranes and not in TT. No differences in 5-HT_2Aabundance were observed between red and white muscle, suggesting that receptor expression does not correlate with the metabolic or contractile properties of the muscle fibre. Our data indicate that 5-HT_2Aexpression in skeletal muscle is maintained into adulthood and that its absence from TT make it an unlikely participant in the excitation-contraction coupling process.

References (24)

S.J. Peroutka
Trends In Neurosciences
(1995)
J.M. Launay et al.
J. Biol. Chem.
(1996)
I. Guillet-Deniau et al.
J. Biol. Chem.
(1997)
A. Klip et al.
FEBS Letters
(1987)
M.M. Bradford
Anal. Biochem.
(1976)
D.P. Felsenfeld et al.
J. Biol. Chem.
(1988)
H.S. Hundal et al.
FEBS Letters
(1993)
Y. Sugimoto et al.
Life Sciences
(1991)
L.H. Tecott et al.
Nature
(1995)
S.A. Smith et al.
Biochem. J.
(1977)

B.L. Furman et al.

Diabetologia

(1980)

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Early life fluoxetine treatment causes long-term lean phenotype in skeletal muscle of rats exposed to maternal lard-based high-fat diet
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There is a concern about early life exposure to Selective Serotonin Reuptake Inhibitors (SSRI) in child development and motor system maturation. Little is known, however, about the interaction of environmental factors, such as maternal nutrition, associated with early exposure to SSRI. The increased maternal consumption of high-fat diets is worrisome and affects serotonin system development with repercussions in body phenotype. This study aimed to assess the short- and long-term effects of neonatal fluoxetine treatment on the body and skeletal muscle phenotype of rats exposed to a maternal lard-based high-fat (H) diet during the perinatal period. A maternal lard-based high-fat diet causes reduced birth weight, a short-term reduction in type IIA fibers in the soleus muscle, and in type IIB fibers in the Extensor Digitorum Longus (EDL) muscle, reducing Lactate Dehydrogenase (LDH) activity in both muscles. In the long-term, the soleus showed reduced muscle weight, smaller area and perimeter of muscle fibers, while the EDL muscle showed reduced Citrate Synthase (CS) activity in offspring from the rats on the maternal lard-based high-fat diet. Early-life exposure to fluoxetine reduced body weight and growth and reduced soleus weight and enzymatic activity in young rats. Exposure to neonatal fluoxetine in adult rats caused a decreased body mass index, less food intake, and reduced muscle weight with reduced CS and LDH activity. Neonatal fluoxetine in young rats exposed to a maternal lard-based high-fat diet caused reduced body weight and growth, reduced soleus weight as well as area and perimeter of type I muscle fibers. In adulthood, there was a reduction in food intake, increased proportion of IIA type fibers, reduced area and perimeter of type IIB, and reduction in levels of CS activity in EDL muscle. Neonatal fluoxetine treatment in rats exposed to a maternal lard-based, high-fat diet induces a reduction in muscle weight, an increase in the proportion of oxidative fibers and greater oxidative enzymatic activity in adulthood.
Muscular and mitochondrial effects of long-term fluoxetine treatment in mice, combined with physical endurance exercise on treadmill
2019, Life Sciences
Citation Excerpt :
Mice treated with fluoxetine appear to have better neuromuscular adaptation to recruit more motor units for higher force production than control groups. Some studies have demonstrated that activation of the 5-HT2A serotonin receptor in skeletal muscle induces the expression of genes involved in myogenesis and confirms its participation in excitation-contraction coupling [32]. The studies show the role of fluoxetine in prevention of degeneration of skeletal muscle [33] as well as improvement of motor activity [34].
Fluoxetine, one of the first newer SSRI antidepressant, is an extremely popular treatment for depression that could improve mental health problems. Many recent studies have suggested that SSRI have potential beneficial effects on skeletal muscle tissue.
We evaluated the potential beneficial effects of oral fluoxetine (18 mg/kg/day for 6 weeks) on muscle performance, after 6 weeks of physical exercise on treadmill. Male mice were randomly assigned to four groups (n = 12 per group) for treatment. Each group received treatment with following specifications: 1) no exercise with vehicle treatment (SED-S); 2) no exercise with fluoxetine treatment (SED-F); 3) exercise with vehicle treatment (EX-S); and 4) exercise with fluoxetine treatment (EX-F). Exercise performances were assessed based on the exhaustive running time and forelimb grip strength, anxious behavior by elevated plus-maze and open-field tests. Mitochondrial enzymes activity and ROS production were measured in the gastrocnemius and soleus muscles.
Fluoxetine treatment had a significant effect on maximal aerobic capacity in mice without exercise, but more significant effects on gripping strength and anxiety when combined with exercise training, e.g. increased strength and decreased anxiety.
Fluoxetine treatment and exercise stimulation also had synergistic effects on strength and increased mitochondrial activity, cellular oxidative and antioxidant capacity in two different muscles.
Selective serotonin reuptake inhibitors affect structure, function and metabolism of skeletal muscle: A systematic review
2018, Pharmacological Research
Citation Excerpt :
Evidence suggests that the functional serotonin 5-HT2 A receptor is expressed in rat myoblasts, activating intracellular phosphorylation, on the plasma membrane and at the level of T-tubules in contracting myotubes [21]. Conversely, it is believed that this receptor is located exclusively in the plasma membrane and is thus unlikely to be related to the muscle excitation-contraction process [22]. In response to altered 5-HT signalling, this receptor seems to influence myogenic differentiation and muscle glucose utilization [21].
Selective Serotonin Reuptake Inhibitors (SSRIs) may have side effects, such as stiffness, tremors and altered tonic activity, as well as an increased risk of developing insulin resistance and diabetes mellitus. However, little is known about the structural, functional and metabolic changes of skeletal muscle after administration of SSRIs. The aim of this systematic review was to explore and discuss the effects of SSRIs on skeletal muscle properties described in human and rodent studies. A systematic search of PUBMED, SCOPUS, and WEB OF SCIENCE was performed. The inclusion criteria were intervention studies in humans and rodents that analysed the effects of SSRIs on skeletal muscle properties. The research found a total of six human studies, including two randomized controlled trials, one non-randomized controlled trial, one uncontrolled before-after study and two case reports, and six preclinical studies in rodents. Overall, the studies in humans and rodents showed altered electrical activity in skeletal muscle function, assessed through electromyography (EMG) and needle EMG in response to chronic treatment or local injection with SSRIs. In addition, rodent studies reported that SSRIs may exert effects on muscle weight, the number of myocytes and the cross-sectional area of skeletal muscle fibre. The results showed effects in energy metabolism associated with chronic SSRI use, reporting altered levels of glycogen synthase activity, acetyl-CoA carboxylase phosphorylation, citrate synthase activity, and protein kinase B Ser phosphorylation. Moreover, changes in insulin signalling and glucose uptake were documented. In this context, we concluded based on human and rodent studies that SSRIs affect electrical muscle activity, structural properties and energy metabolism in skeletal muscle tissue. However, these changes varied according to pre-existing metabolic and functional conditions in the rodents and humans.
The roles of peripheral serotonin in metabolic homeostasis
2015, FEBS Letters
Citation Excerpt :
Available in vitro experiments suggest that peripheral serotonin might also influence glucose homeostasis in skeletal muscle. Serotonin receptor Htr2a has been found in both white and red muscle fibers [48]. Other experiments indicate that serotonin stimulates skeletal muscle PFK activity and thus augments skeletal muscle glucose consumption through stimulation of glycolysis [49,50].
Metabolic homeostasis in the organism is assured both by the nervous system and by hormones. Among a plethora of hormones regulating metabolism, serotonin presents a number of unique features. Unlike classical hormones serotonin is produced in different anatomical locations. In brain it acts as a neurotransmitter and in the periphery it can act as a hormone, auto- and/or paracrine factor, or intracellular signaling molecule. Serotonin does not cross the blood–brain barrier; therefore the two major pools of this bioamine remain separated. Although 95% of serotonin is produced in the periphery, its functions have been ignored until recently. Here we review the impact of the peripheral serotonin on the regulation of function of the organs involved in glucose and lipid homeostasis.
Importance of serotonin (5-HT) and its precursor L-tryptophan for homeostasis and function of skeletal muscle in rats. A morphological and endocrinological study
2015, Acta Histochemica
Citation Excerpt :
The contraction of skeletal muscle is managed by acetylcholine, a neurotransmitter that allows the flux of Ca2+ through ion channels in the sarcolemma. The Ca2+ flux may also be mediated and regulated by several specific ligands such as glutamate (Cymes and Grosman, 2012) and serotonin (5-HT) (Shuster et al., 1991; Yuan et al., 1997; Hajduch et al., 1999; Huang et al., 2005). 5-HT is a neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and in the enterochromaffin cells of the gastrointestinal tract (Racke et al., 1995).
Serotonin (5-HT) is a neurotransmitter, synthesized in serotonergic neurons of the central nervous system and in enterochromaffin cells of the gastrointestinal tract, which is involved in the regulation of several body functions, including muscle tissue development and growth and its contractile response. l-Tryptophan (l-Trp) is an essential amino acid and precursor of 5-HT. The aim of the present study was to better understand the mechanisms that govern neuroendocrine homeostasis of muscle tissue and emphasize the importance of a diet, complete in all its elements, referring specifically to the essential amino acids such as l-Trp, crucial in several neuroendocrine functions.We analyzed the possible consequences of l-Trp-free diet on 5-HT production and on skeletal muscle morphology and function in young female rats. We also evaluated the eventual alterations of hormone production such as growth hormone (GH), thyroid stimulating hormone (TSH) and thyroid hormones (T₃ and T₄) that control and regulate growth, metabolism and efficiency of the skeletal muscle. Our results showed a strong decrease of 5-HT, GH, TSH, T₃ and T₄ levels associated to a clear difference in body weight between experimental and control rats. Moreover, the muscle samples of experimental rats showed histological and ultrastructural alterations. These findings thus supported a strong link between l-Trp, serotonergic system, hormone secretion and morphology of skeletal muscle tissue and thus, the importance of a balanced daily diet.
The toadfish serotonin 2A (5-HT<inf>2A</inf>) receptor: Molecular characterization and its potential role in urea excretion
2012, Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Citation Excerpt :
Interestingly, the area highest in toadfish 5-HT2A receptor mRNA expression was not the brain but the swim bladder. The swim bladder was stripped of its skeletal muscle, so the 5-HT2A receptor that has been shown to be present in rat skeletal muscle (Guillet-Deniau et al., 1997; Hajduch et al., 1999) should be of no consequence. The gas gland and associated rete mirabile were likely included in the swim bladder preparation (Fänge and Wittenberg, 1958), and so elevated toadfish 5-HT2A receptor transcript may be present in that capacity as rete mirabile in both mammals and fish have been shown to respond to 5-HT (Myhre et al., 1976; Diéguez et al., 1987).
Based on early pharmacological work, the serotonin 2A (5-HT_2A) receptor subtype is believed to be involved in the regulation of toadfish pulsatile urea excretion. The goal of the following study was to characterize the toadfish 5-HT_2A receptor at a molecular level, to determine the tissues in which this receptor is predominantly expressed and to further investigate the pharmacological specificity of toadfish pulsatile urea excretion by examining the effect of ketanserin, a 5-HT_2A receptor antagonist, on resting rates of pulsatile urea excretion. The full-length toadfish 5-HT_2A receptor encodes a 496 amino acid sequence and shares 57–80% sequence identity to 5-HT_2A receptors of other organisms, with 100% conservation among important ligand-binding residues. Toadfish 5-HT_2A receptor mRNA expression was highest in the swim bladder and gonad, followed by the whole brain. All other tissues tested (esophagus, stomach, anterior intestine, posterior intestine, rectum, liver, kidney, heart, muscle and gill) had mRNA expression levels that were significantly less than whole brain. Toadfish 5-HT_2A receptor mRNA expression within the brain was highest in the hindbrain, telencephalon and midbrain/diencephalon regions. Treatment with the 5-HT_2A receptor antagonist, ketanserin, resulted in a significant decrease in the pulsatile component of spontaneous urea excretion due to a reduction in urea pulse size with no significant change in pulse frequency. These results lend further support for the 5-HT_2A receptor in the regulation of pulsatile urea excretion in toadfish.

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Regular ArticleBiochemical Localisation of the 5-HT2A(serotonin) Receptor in Rat Skeletal Muscle

Abstract

Trends In Neurosciences

J. Biol. Chem.

J. Biol. Chem.

FEBS Letters

Anal. Biochem.

J. Biol. Chem.

FEBS Letters

Life Sciences

Nature

Biochem. J.

Diabetologia

Regular Article
Biochemical Localisation of the 5-HT_2A(serotonin) Receptor in Rat Skeletal Muscle