Species variations in RU 24969 interactions with non-5-HT1A binding sites

Heuring, Richard E.; Schlegel, Jerry R.; Peroutka, Stephen J.

doi:10.1016/0014-2999(86)90114-7

Cited by 93 publications

(29 citation statements)

References 9 publications

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“…5-H T~A agonists are virtually inactive at the nerve terminal 5-HT autoreceptor which is thought to modulate the release of 5-HT (Engel et al, 1986;Middlemiss, 1984a), and evidence is accumulating that this presynaptic autoreceptor may be of the ~-H T~B subtype (Engel et al, 1986;Middlemiss, 1984bMiddlemiss, , 1985. However, the general physiological role of 5-HTl~ receptors in brain remains unclear as recent studies indicate that this subtype is not present in certain species, including humans (Heuring et al, 1986;Hoyer et al, 1986). In any case, the present study strengthens the contention of others (Martin and Sanders-Bush, 1982) that the somatodendritic 5-HT autoreceptor is distinct from the presynaptic 5-HT autoreceptor in that the relative potencies of the 5-HTlA and ~-H T~B compounds are reversed at the two sites.…”

Section: Discussionmentioning

confidence: 99%

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Sprouse¹,

Aghajanian²

1987

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335

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A direct comparison was made of the effects of serotonin 5 -H T 1~ and 5-H T~B selective compounds on the spontaneous firing rate of dorsal raphe serotoninergic neurons in chloral-hydrate-anesthetized rats. Following intravenous administration, the ~-H T~A selective compounds ipsapirone (TVX Q 7821) and LY 165163 potently inhibited single-unit activity in a dose-dependent manner whereas the ~-H T~B selective compounds, m-chlorophenylpiperaine (mCPP) and trifluoromethylphenylpiperazine (TFMPP), displayed only weak or irregular actions. Low microiontophoretic currents of ipsapirone and LY 165163 were also effective in suppressing spontaneous firing; dose-response relationships for the ~-H T~A compounds were indistinguishable from that of 5-HT itself. In contrast, dorsal raphe neurons were only weakly responsive to microiontophoretic application of mCPP and TFMPP dose-response relationships for the ~-H T~B compounds were significantly displaced from that of 5-HT. In intracellular studies, ipsapirone and LY 165163, when added to the media bathing brain slices, mimicked the actions of 5-HT in hyperpolarizing dorsal raphe cell membranes and decreasing input resistance; however, the maximal effects of the 5-Efl"l'~ compounds on these membrane properties exceeded those of 5-HT. In summary, dorsal raphe 5-HT neurons appear highly responsive to 5-H T 1~, but not to ~-H T~B compounds; these findings are discussed with regard to the 5-HT receptor subtypes as candidates for the somatodendritic autoreceptor of dorsal raphe Ipsapirone, LY 165163, mCPP, TFMPP neurons.

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Section: Discussionmentioning

confidence: 99%

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Sprouse¹,

Aghajanian²

1987

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827

335

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“…In addition to 5-HTlA-receptors, both 5-HT1B (Bouhelal et al, 1988) and 5-HTlD sites Schoeffter et al, 1988) have been shown to be negatively coupled with adenylate cyclase. 5-HT1B sites could not be characterized in the brain of species other than the rat and the mouse (Hoyer et al, 1985ab;1986;Hoyer, 1988;Heuring et al, 1986;Hamblin et al, 1987). Moreover, according…”

Section: Discussionmentioning

confidence: 99%

Centrally acting hypotensive agents with affinity for 5‐HT_1A binding sites inhibit forskolin‐stimulated adenylate cyclase activity in calf hippocampus

Schoeffter¹,

Hoyer²

1988

British J Pharmacology

147

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inhibition for all but the latter two agonists (14%).3 The following hypotensive agents with high affinity for 5-HTIA sites were potent agonists in this system (mean EC50 value, nM): flesinoxan (24), indorenate (99), erythro-1-{1-[2-(1,4-benzodioxan-2-yl)-2-hydroxyethyl]4-piperidyl}-2-benzimidazolinone (R 28935, 2.5), urapidil (390) and 5-methylurapidil (3.5). The first two agents were full agonists, whereas the latter three acted as partial agonists with 60-80% efficacy.

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“…In some species, 5-HTIB receptors are presynaptic receptors controlling neurotransmitter release. However, this receptor subtype has not been found in the guinea-pig ileum (Heuring et al, 1987), so 5-HTIB receptor ligands were not investigated in this study.…”

Section: Discussionmentioning

confidence: 99%

On the nature of the 5‐HT receptor subtype inhibiting acetylcholine release in the guinea‐pig ileum

Ramı́rez

Rı́o

Cenarruzabeitia

et al. 1994

British J Pharmacology

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1 The nature of the 5-hydroxytryptamine (5-HT) receptor subtype controlling acetylcholine release and contraction induced by stimulation of the neurokinin NK3 receptor has been studied in the longitudinal muscle-myenteric plexus preparation from guinea-pig ileum. 2 In preparations preloaded with [3H]-choline, the selective NK3 agonist, senktide, produced a concentration-dependent increase in tritium overflow, an index of [3H]-acetylcholine release. Low concentrations of neurokinin B, also markedly increased tritium efflux. 3 The senktide-induced acetylcholine release was markedly increased by the same concentration of methysergide and mesulergine. The 5-HT2A,2c agonist DOI (1 jtM) inhibited the tritium overflow while 8-OH-DPAT, sumatriptan and ketanserin (1 pM each) were without effect on the senktide-induced tritium efflux. 4 The contractile response to senktide in the guinea-pig ileum was attenuated by atropine, 0.1 ZM.Methysergide, a 5-HTI/2 receptor antagonist, and mesulergine, a 5-HT2A/2B/2C receptor antagonist, (1 fLM each), enhanced the contractile effect of the NK3 receptor agonist. 5 It is concluded that the acetylcholine release induced by a NK3 receptor agonist is inhibited by stimulation of a 5-HT receptor, possibly of the 5-HT2C or 5-HT2B subtype.

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Species variations in RU 24969 interactions with non-5-HT1A binding sites

Cited by 93 publications

References 9 publications

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Centrally acting hypotensive agents with affinity for 5‐HT_1A binding sites inhibit forskolin‐stimulated adenylate cyclase activity in calf hippocampus

On the nature of the 5‐HT receptor subtype inhibiting acetylcholine release in the guinea‐pig ileum

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Species variations in RU 24969 interactions with non-5-HT1A binding sites

Cited by 93 publications

References 9 publications

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT1A and 5‐HT1B agonists

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT1A and 5‐HT1B agonists

Centrally acting hypotensive agents with affinity for 5‐HT1A binding sites inhibit forskolin‐stimulated adenylate cyclase activity in calf hippocampus

On the nature of the 5‐HT receptor subtype inhibiting acetylcholine release in the guinea‐pig ileum

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Product

Resources

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Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Electrophysiological responses of serotoninergic dorsal raphe neurons to 5‐HT_1A and 5‐HT_1B agonists

Centrally acting hypotensive agents with affinity for 5‐HT_1A binding sites inhibit forskolin‐stimulated adenylate cyclase activity in calf hippocampus