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Query: UNIPROT:P08908 (5-HT1A)
 5,574 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in tension were monitored isometrically on helical strips from both femoral and saphenous human veins obtained during autopsy and during surgical removal of varicose veins respectively. Both venous tissues contracted in response to 5-hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT) and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT). While 5-HT was about 2 times more potent in saphenous (pD2 = 7.35) than in femoral veins (pD2 = 7.04), 5-CT stimulated the saphenous vein (pD2 = 7.62) at about 20 times lower concentrations than were required for stimulation of the femoral vein (pD2 = 6.27). 8-OH-DPAT induced venoconstriction only when used at very high concentrations and pD2 values could not be determined. These data suggested different subtypes and/or distribution of 5-HT receptors in both venous preparations. Further evidence for this was obtained by the observation that spiperone (a 5-HT receptor blocker with high affinity for 5-HT2 and 5-HT1A sites) produced a parallel shift to the right of the 5-HT curve in femoral veins but elicited a biphasic displacement of the 5-HT curve in saphenous veins. In the femoral vein, spiperone showed a pA2 value of 9.20 +/- 0.08, statistically not different from that calculated for the spiperone sensitive 5-HT effect in saphenous vein (pA2 = 9.14 +/- 0.08). The results suggest that regional variations in the distribution of 5-HT receptor subtypes do exist, human femoral veins possessing mainly 5-HT2 receptors whereas in human saphenous veins both 5-HT1-like and 5-HT2 receptors are present.
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PMID:Heterogeneity of 5-HT receptor subtypes in isolated human femoral and saphenous veins. 847 33

Serotonin (5-HT) has been shown to modulate brain maturation during development and adult plasticity. This effect in the whole animal may be due to activation of 5-HT1A receptors and a corresponding increases in S100b and corticosterone. Synaptophysin, an integral protein of the synaptic vesicle membrane that correlates with synaptic density and neurotransmitter release, is reduced by depletion of 5-HT in the cortex and hippocampus of the adult rat. Injections of a 5-HT1A agonist or dexamethasone can reverse the loss of synaptophysin immunoreactivity (IR). In this study we used morphometric analysis of synaptophysin-IR to study the effects of the 5-HT1A agonist, ipsapirone, and the neuronal extension factor, S100b on hippocampal neurons grown in a serum and steroid free media. Both compounds increased the synaptophysin-IR at doses previously established to be highly specific. Ipsapirone (10(-9)M) was more effective on neuronal cell bodies staining and S100b (10 ng/ml) was more effective in increasing the number of synaptophysin-IR varicosities on neuronal processes. In addition both types of corticosteroid receptor agonists, at previously established specific doses, Ru28362 (10(-8) M) and aldosterone (10(-9) M) produced smaller increases compared to control groups in both the cell body staining and the number of varicosities. The effect of these differentiating factors on the expression of synaptophysin-IR suggests multiple regulation sites for producing and maintaining pre-synaptic elements in the brain.
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PMID:Enhanced synaptophysin immunoreactivity in rat hippocampal culture by 5-HT 1A agonist, S100b, and corticosteroid receptor agonists. 872 30

Activation of NMDA receptors evokes sustained fictive locomotion in the isolated spinal cord of the sea lamprey Petromyzon marinus (P. marinus), but in the river lamprey Lampetra fluviatilis (L. fluviatilis) the ventral root activity is often irregular. A previous study showed that the number of 5-HT immunoreactive fibres, neurones and varicosities are much lower in the spinal cord of L. fluviatilis than in P. marinus. To further analyse the underlying mechanisms, the present study investigated the role of the 5-HT system in stabilising fictive locomotion. In P. marinus a blockade of 5-HT1A receptors by spiperone reversibly increased the frequency and the coefficient of variation. This implies that there is an endogenous release of 5-HT during fictive locomotion that is important for the generation of locomotor activity. In L. fluviatilis bath applied NMDA or D-glutamate evoked in most cases irregular activity. An addition of 5-HT (0.5-2 microM) rapidly stabilised the burst generation and led to a sustained fictive locomotion. In a split-bath configuration, NMDA administered to the rostral part of the spinal cord in P. marinus evoked fictive locomotion in both the rostral part and the first few segments of the caudal part. When spiperone was added to the caudal part, the burst activity changed into tonic activity within 10 min. Taken together, these results indicate that activity in the intrinsic 5-HT system in the lamprey spinal locomotor network contributes significantly to the rhythm generation. The quantitative differences with regard to the 5-HT plexus between P. marinus and L. fluviatilis may account for the observed discrepancy between the two species.
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PMID:The spinal 5-HT system contributes to the generation of fictive locomotion in lamprey. 1101 Oct 21

5-HT1A knockout (KO) mice display an anxious-like phenotype, whereas 5-HT1B KOs are over-aggressive. To identify serotoninergic correlates of these altered behaviors, autoradiographic measurements of 5-HT1A and 5-HT1B serotonin (5-HT) receptors and transporter (5-HTT) were obtained using the radioligands [3H]8-OH-DPAT, [125I]cyanopindolol and [3H]citalopram, respectively. By comparison to wild-type, density of 5-HT1B receptors was unchanged throughout brain in 5-HT1A KOs, and that of 5-HT1A receptors in 5-HT1B KOs. In contrast, decreases in density of 5-HTT binding were measured in several brain regions of both genotypes. Moreover, 5-HTT binding density was significantly increased in the amygdalo-hippocampal nucleus and ventral hippocampus of the 5-HT1B KOs. Measurements of 5-HT axon length and number of axon varicosities by quantitative 5-HT immunocytochemistry revealed proportional increases in the density of 5-HT innervation in these two regions of 5-HT1B KOs, whereas none of the decreases in 5-HTT binding sites were associated with any such changes. Several conclusions could be drawn from these results: (i) 5-HT1B receptors do not adapt in 5-HT1A KOs, nor do 5-HT1A receptors in 5-HT1B KOs. (ii) 5-HTT is down-regulated in several brain regions of 5-HT1A and 5-HT1B KO mice. (iii) This down-regulation could contribute to the anxious-like phenotype of the 5-HT1A KOs, by reducing 5-HT clearance in several territories of 5-HT innervation. (iv) The 5-HT hyperinnervation in the amygdalo-hippocampal nucleus and ventral hippocampus of 5-HT1B KOs could play a role in their increased aggressiveness, and might also explain their better performance in some cognitive tests. (v) These increases in density of 5-HT innervation provide the first evidence for a negative control of 5-HT neuron growth mediated by 5-HT1B receptors.
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PMID:Regional changes in density of serotonin transporter in the brain of 5-HT1A and 5-HT1B knockout mice, and of serotonin innervation in the 5-HT1B knockout. 1148 65

The release of 5-HT in terminal areas of the rodent brain is regulated by 5-HT1B receptors. Here we examined the role of 5-HT1B receptors in the control of 5-HT output and firing in the dorsal raphe nucleus (DR), median raphe nucleus (MnR) and forebrain of the rat in vivo. The local perfusion (30-300 microM) of the selective 5-HT1B receptor agonist CP-93,129 to freely moving rats decreased 5-HT release in the DR and more markedly in the MnR. Likewise, 300 microM CP-93,129 reduced 5-HT output in substantia nigra pars reticulata, ventral pallidum, lateral habenula and the suprachiasmatic nucleus. The effect of CP-93,129 was prevented by SB-224289, but not by WAY-100635, selective 5-HT1B and 5-HT1A receptor antagonists, respectively. SB-224289 did not alter dialysate 5-HT in any raphe nuclei. The intravenous administration of the brain-penetrant selective 5-HT1B receptor agonist CP-94,253 (0.5-2.0 mg/kg) to anesthetized rats decreased dialysate 5-HT in dorsal hippocampus and globus pallidus, increased it in MnR and left it unaltered in the DR and medial prefrontal cortex. SB-224289, at a dose known to block 5-HT1B autoreceptor-mediated effects (5 mg/kg), did not prevent the effect of CP-94,253 on MnR 5-HT. The intravenous administration of CP-94,253 (0.05-1.6 mg/kg) to anesthetized rats increased the firing rate of MnR, but not DR-5-HT neurons. The local perfusion of CP-94,253 in the MnR showed a biphasic effect, with 5-HT reductions at 0.3-3 microM and increase at 300 microM. These results suggest that 5-HT cell firing and release in midbrain raphe nuclei (particularly in the MnR) are under control of 5-HT1B receptors. The activation of 5-HT1B autoreceptors (possibly located on 5-HT nerve endings and/or varicosities within DR and MnR) reduces 5-HT release. The effects of higher concentrations of 5-HT1B receptor agonists seem more compatible with the activation of 5-HT1B heteroreceptors on inhibitory neurons.
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PMID:The role of 5-HT1B receptors in the regulation of serotonin cell firing and release in the rat brain. 1159 69