Venlafaxine and its interaction with WAY 100635: effects on serotonergic unit activity and behavior in cats

Bjorvatn, Bjørn; Fornal, Casimir A.; Martín, Francisco Javier Escalada San; Metzler, Christine W.; Jacobs, Barry L.

doi:10.1016/s0014-2999(00)00622-1

Cited by 17 publications

(14 citation statements)

References 34 publications

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“…This would result in an increase in the firing rate of the 5-HT neurons and consequently in an increase of 5-HT release in postsynaptic areas. Although WAY-100635 was originally considered a silent antagonist , a growing body of evidence has demonstrated that this drug can, in fact, increase the firing rate of 5-HT neurons (Mundey et al 1996;Fornal et al 1996;Bjorvatn et al 2000;Hajós et al 2001) and increase the release of 5-HT in projection areas of both the median and the dorsal raphe nuclei (Bosker et al 1996;Dudley et al 1999).…”

Section: Discussionmentioning

confidence: 99%

Serotonergic neurons in the median raphe nucleus regulate inhibitory avoidance but not escape behavior in the rat elevated T-maze test of anxiety

2004

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Section: Discussionmentioning

confidence: 99%

Serotonergic neurons in the median raphe nucleus regulate inhibitory avoidance but not escape behavior in the rat elevated T-maze test of anxiety

2004

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“…3), indicating that the putative tonic facilitatory mechanism in PNS inhibition mediated by 5-HT 2 and 5-HT 3 receptors was suppressed rather than enhanced by duloxetine. The reversal by WAY100635 of the duloxetine effect on PNS inhibition suggests that this may occur by modulation of bulbospinal 5-HT pathways that originate in medullary raphe nucleus and generate the release of 5-HT at various sites in the spinal cord, including the dorsal horn and autonomic nuclei (Gartside et al, 1997;Bjorvatn et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Administration of SNRIs such as duloxetine and venlafaxine as well as selective SNRIs is known to increase 5-HT concentrations in brain stem raphe nucleus, which in turn leads to activation of 5-HT 1A autoreceptors expressed on the serotonergic raphe neurons, resulting in a decline in raphe neuron firing (Gartside et al, 1997;Bjorvatn et al, 2000) that could decrease tonic 5-HT release in the spinal cord. This negative feedback mechanism in the raphe nucleus would counteract a possible downstream duloxetine effect on 5-HT 2/3 mechanisms in the spinal cord (Gobert et al, 1995;Fornal et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…When used clinically, a low dose of duloxetine might cause fewer side effects, whereas its efficacy in the treatment of OAB might still be maintained when combined with PNS. Because the facilitatory effect of duloxetine on 5-HT mechanisms can be suppressed by activation of the 5-HT 1A autoreceptors on serotonergic neurons in the raphe nucleus (Gartside et al, 1997;Bjorvatn et al, 2000), WAY100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide; a 5-HT 1A receptor antagonist) was also used to investigate the role of 5-HT 1A receptors in duloxetine and PNS inhibition of bladder overactivity.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Duloxetine and WAY100635 on Pudendal Inhibition of Bladder Overactivity in Cats

Reese

Xiao

Schwen

et al. 2014

J Pharmacol Exp Ther

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This study was aimed at determining the effect of duloxetine (a serotonin-norepinephrine reuptake inhibitor) on pudendal inhibition of bladder overactivity. Cystometrograms were performed on 15 cats under a-chloralose anesthesia by infusing saline and then 0.25% acetic acid (AA) to induce bladder overactivity. To inhibit bladder overactivity, pudendal nerve stimulation (PNS) at 5 Hz was applied to the right pudendal nerve at two and four times the threshold (T) intensity for inducing anal twitch. Duloxetine (0.03-3 mg/kg) was administered intravenously to determine the effect on PNS inhibition. AA irritation significantly (P , 0.01) reduced bladder capacity to 27.9 6 4.6% of saline control capacity. PNS alone at both 2T and 4T significantly (P , 0.01) inhibited bladder overactivity and increased bladder capacity to 83.6 6 7.6% and 87.5 6 7.7% of saline control, respectively. Duloxetine at low doses (0.03-0.3 mg/kg) caused a significant reduction in PNS inhibition without changing bladder capacity. However, at high doses (1-3 mg/kg) duloxetine significantly increased bladder capacity but still failed to enhance PNS inhibition. WAY100635cyclohexanecarboxamide; a 5-HT 1A receptor antagonist, 0.5-1 mg/kg i.v.) reversed the suppressive effect of duloxetine on PNS inhibition and significantly (P , 0.05) increased the inhibitory effect of duloxetine on bladder overactivity but did not enhance the effect of PNS. These results indicate that activation of 5-HT 1A autoreceptors on the serotonergic neurons in the raphe nucleus may suppress duloxetine and PNS inhibition, suggesting that the coadministration of a 5-HT 1A antagonist drug might be useful in enhancing the efficacy of duloxetine alone and/or the additive effect of PNSduloxetine combination for the treatment of overactive bladder symptoms.

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“…In addition, although St. John's wort has been shown to inhibit the uptake of norepinephrine and dopamine in vitro, it is unlikely that such a blockade would interfere with the ability of serotonin reuptake inhibitors to suppress neuronal activity in vivo. This is supported in part by the fact that dual serotonin/norepinephrine reuptake inhibitors, such as duloxetine and venlafaxine, potently inhibit the firing rate of serotonergic neurons in both the anesthetized and freely moving animal (Gartside et al 1997;Béïque et al 1999;Bjorvatn et al 2000).…”

Section: Discussionmentioning

confidence: 99%

Effects of Standardized Extracts of St. John's Wort on the Single-Unit Activity of Serotonergic Dorsal Raphe Neurons in Awake Cats Comparisons with Fluoxetine and Sertraline

Fornal

Metzler

Mirescu

et al. 2001

Neuropsychopharmacology

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St. John's wort, p.o.) and i.v.). Both preparations were found to have no effect on neuronal activity. This contrasts sharply with the action of fluoxetine and sertraline (2 mg/kg, p.o.) 8-hydroxy-2-(di-n-propylamino)tetralin (10 g/kg, i.v.). Overall, these -hydroxytryptamine (serotonin); ElectrophysiologyThe medicinal plant Hypericum perforatum L., commonly known as St. John's wort, appears to be an effective antidepressant with few side effects (Hippius 1998;Wheatley 1998;Vitiello 1999). In Germany, where extracts of the plant are licensed as a medication, St. John's wort or hypericum is used more extensively than et al. 1996). Since the publication of that influential report, several other systematic reviews (and one metaanalysis) have appeared which further support the antidepressant efficacy of hypericum (Josey and Tackett 1999;Kim et al. 1999;Stevinson and Ernst 1999;Gaster and Holroyd 2000). Furthermore, in comparison with other antidepressants, St. John's wort is well tolerated and has a low side effect profile (Linde et al. 1996;Ernst et al. 1998 Despite its widespread use, the active constituents and mechanism of antidepressant action of St. John's wort remain largely unknown (Bennett et al. 1998;Nathan 1999). A number of studies have shown that crude hypericum preparations and some of the constituents can inhibit monoamine oxidase (MAO) activity in vitro (Demisch et al. 1989;Thiede and Walper 1994;Cott 1997;. However, the clinical relevance of this pharmacological effect is questionable, since it occurs only at high concentrations and has not been observed in vivo (Bladt and Wagner 1994;Yu 2000). More recent studies have focused on the capacity of St. John's wort to inhibit the uptake of brain monoamines, particularly serotonin Neary and Bu 1999). Perovic and Müller (1995) were the first to report that a crude hypericum extract inhibited the uptake of serotonin in rat cortical synaptosomes at relatively low concentrations and conclude that the antidepressant activity of St. John's wort is due to this action. Hypericum has also been shown to inhibit the synaptosomal uptake of dopamine and norepinephrine, at concentrations similar to those found to inhibit the uptake of serotonin . In subsequent studies, the chemical substance hyperforin was identified as one of the major uptake-inhibiting components of St. John's wort Chatterjee et al. 1998;Singer et al. 1999). The content of this substance has recently been associated with the clinical antidepressant action of St. John's wort (Laakmann et al. 1998), suggesting that hyperforin is at least partially responsible for the antidepressant properties of the herb. Other evidence suggest that hypericum extracts may enhance the release of serotonin from presynaptic stores (Gobbi et al. 1999). Neurochemical studies have shown that St. John's wort increases serotonin metabolism and/or turnover in various brain regions (Calapai et al. 1999;Yu 2000). Finally, it has been hypothesized that the clinical efficacy of St. John's wort may result from a combinati...

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Venlafaxine and its interaction with WAY 100635: effects on serotonergic unit activity and behavior in cats

Cited by 17 publications

References 34 publications

Serotonergic neurons in the median raphe nucleus regulate inhibitory avoidance but not escape behavior in the rat elevated T-maze test of anxiety

Serotonergic neurons in the median raphe nucleus regulate inhibitory avoidance but not escape behavior in the rat elevated T-maze test of anxiety

Effects of Duloxetine and WAY100635 on Pudendal Inhibition of Bladder Overactivity in Cats

Effects of Standardized Extracts of St. John's Wort on the Single-Unit Activity of Serotonergic Dorsal Raphe Neurons in Awake Cats Comparisons with Fluoxetine and Sertraline

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