Search results for "5-HT"
showing 10 items of 134 documents
A constitutively active pituitary adenylate cyclase activating polypeptide (PACAP) type I receptor shows enhanced photoaffinity labeling of its highl…
2001
Abstract In the present study, we have analyzed a previously identified constitutively active pituitary adenylate cyclase activating polypeptide (PACAP) type I (PAC1) receptor with a deletion of the single amino acid residue Glu 261 (Y.-J. Cao, G. Gimpl, F. Fahrenholz, A mutation of second intracellular loop of pituitary adenylate cyclase activating polypeptide type I receptor confers constitutive receptor activation, FEBS Lett. 469 (2000)). This glutamic acid residue is highly conserved within the second intracellular loop of class II G protein-coupled receptors and may thus be of importance for many members of this receptor class. To explore the molecular characteristics of this mutant re…
Effect of serotonin and calcium in normal and sensitized guinea pig isolated trachea
1996
Tracheal strips from normal and actively sensitized guinea pigs were studied to determine the responses to serotonin (5-hydroxytryptamine, 5-HT ; 1 nM - 0.1 mM) and ouabain (0.1 μM - 0.1 mM), and the effects of increasing the extracellular calcium (Ca o ) concentration on tonic contractions elicited by 5-HT. Sensitized trachea exhibited an increased responsiveness and sensitivity to 5-HT and ouabain. Increases in Ca o to achieve final concentrations of 5, 10 and 20 mM caused concentration-related relaxations of normal and sensitized tissues contracted to a similar plateau level with 5-HT. Inhibition of the Na + /K + -ATPase by ouabain (10 μM) reversed the effects of Ca o from relaxation to …
Withanone Ameliorates Stress Symptoms in Caenorhabditis Elegans by Acting through Serotonin Receptors
2021
ABSTRACT Introduction Depression is responsible for 800 000 deaths worldwide, a number that will rise significantly due to the COVID-19 pandemic. Affordable novel drugs with less severe side effects are urgently required. We investigated the effect of withanone (WN) from Withania somnifera on the serotonin system of wild-type and knockout Caenorhabditis elegans strains using in silico, in vitro, and in vivo methods. Methods WN or fluoxetine (as positive control drug) was administered to wild-type (N2) and knockout C. elegans strains (AQ866, DA1814, DA2100, DA2109, and MT9772) to determine their effect on oxidative stress (Trolox, H2DCFDA, and juglone assays) on osmotic stress and heat stres…
Immunological Probes for the Bradykinin B2 Receptor. A Toolbox
1997
Publisher Summary This chapter provides an overview of the immunological tools for bradykinin (BK) B 2 receptor. Receptors for kinins are classified as two major subtypes, B 1 and B 2 , although other subtypes may exist. B 1 receptors are activated by carboxyterminally truncated kinins, whereas BK and kallidin (Lys-BK) are B 2 receptor agonists. Molecular cloning has revealed the primary structures of B 1 and B 2 receptors and identified them as members of the G protein-coupled receptor family, characterized by seven membrane-spanning α-helices. In some tissues, B 1 receptor expression is induced by cytokines, such as interleukin-1, whereas the B 2 receptor is thought to be expressed consti…
Differential influence of Pomphorhynchus laevis (Acanthocephala) on brain serotonergic activity in two congeneric host species.
2007
The physiological mechanisms by which parasites with complex life cycles manipulate the behaviour of their intermediate hosts are still poorly understood. In Burgundy, eastern France, the acanthocephalan parasitePomphorhynchus laevisinverses reaction to light in its amphipod hostGammarus pulex, but not inGammarus roeseli, a recent invasive species. Here, we show that this difference in manipulation actually reflects a difference in the ability of the parasite to alter brain serotonergic (5-HT) activity of the two host species. Injection of 5-HT in uninfected individuals of both host species was sufficient to inverse reaction to light. However, a difference in brain 5-HT immunocytochemical s…
Induction of stress resistance and extension of lifespan in Chaenorhabditis elegans serotonin-receptor knockout strains by withanolide A
2021
Abstract Introduction Approximately 300 million people worldwide suffer from depression. The COVID-19 crisis may dramatically increase these numbers. Severe side effects and resistance development limit the use of standard antidepressants. The steroidal lactone withanolide A (WA) from Withania somnifera may be a promising alternative. Caenorhabditis elegans was used as model to explore WA's anti-depressive and anti-stress potential. Methods C. elegans wildtype (N2) and deficient strains (AQ866, DA1814, DA2100, DA2109 and MT9772) were used to assess oxidative, osmotic or heat stress as measured by generation of reactive oxygen species (ROS), determination of lifespan, and mRNA expression of …
Effects of 8-OH-DPAT on open field performance of young and aged rats prenatally exposed to diazepam: a tool to reveal 5-HT1A receptor function
2003
Central GABAergic and serotoninergic systems interact with one another and are implicated in controlling different behaviours. A gentle early long-lasting handling can prevent the deficits in locomotion and exploration in open field (O.F.) in 3-month-old male rats prenatally exposed to diazepam (DZ). Purpose of this study was to extend the research to older handled rats prenatally exposed to DZ and to assess the activity of 5-HT1A receptors (Rs), evaluating the performance in O.F. at 3 and 18 months of age following 8-OH-DPAT administration. A single daily s.c. injection of DZ (1.5 mg/kg) from gestation day 14 to gestation day 20 induced in aged, but not in young rats, a decrease in total d…
Selective activation of 5-HT(2C) receptors stimulates GABA-ergic function in the rat substantia nigra pars reticulata: a combined in vivo electrophys…
2007
In vivo electrophysiology and microdialysis were used to investigate the physiological role of 5-HT(2C) receptors in the control of substantia nigra pars reticulata (SNr) function. Extracellular single-unit recordings were performed from putative GABA-containing neurons in the SNr of anesthetized rats, and local GABA release was studied by in vivo microdialysis in the SNr of awake freely-moving rats. Systemic administration of the selective 5-HT(2C) receptor agonist (S)-2-(chloro-5-fluoro-indol-1-yl)-1-methylethylamine 1:1 C(4)H(4)O(4) (RO 60-0175) caused a dose-dependent excitation of about 30% of the SNr neurons recorded. However, the remaining neurons were either inhibited or unaffected …
High dose of 8-OH-DPAT decreases maximal dentate gyrus activation and facilitates granular cell plasticity in vivo.
2013
Although several studies have emphasized a crucial role for the serotonergic system in the control of hippocampal excitability, the role of serotonin (5-HT) and its receptors in normal and pathologic conditions, such as temporal lobe epilepsy (TLE), is still unclear. The present study was therefore designed firstly to investigate the acute effect of 8-OH-DPAT, a mixed 5-HT1A/7 receptor agonist, at a high dose (1 mg/kg, i.p.) known to have antiepileptic properties, in a model of acute partial epilepsy in rats. For this purpose, a maximal dentate activation (MDA) protocol was used to measure electrographic seizure onset and duration. In addition, the effect of 8-OH-DPAT on in vivo dentate gyr…
Serotonergic modulation of rat pineal gland activity: in vivo evidence for a 5-Hydroxytryptamine(2C) receptor involvement
2000
There are some suggestions that, in the pineal gland, serotonin acts not only as a precursor of melatonin but also plays a role in the modulation of the pineal biosynthetic activity. To corroborate this possible neuromodulatory role of 5-hydroxytryptamine (serotonin) (5-HT) on the pineal gland, the effects of two 5-HT(2) receptor agonists meta-chlorophenylpiperazine (m-CPP) and 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane were assessed in vivo on pineal N-acetyltransferase (NAT) activity and melatonin content in rats. m-CPP potentiated the enhancement of NAT activity and pineal melatonin content induced by isoproterenol administration during daytime, whereas it did not affect the diurnal …