Selective 5-HT1D alpha serotonin receptor gene expression in trigeminal ganglia: implications for antimigraine drug development.

Abstract

Pharmacological data suggest that the actions of -antimiine drugs such as sumatriptn may be medated by 5-HT1D-lke serotonin recepors on trigemnhovascular nerve endings. We sought molecular evidence for the expreion of an mRNA species encoding the 5-HT1D receptor subtype in guinea pig and human trigeminal g i, using the polymerase chain reaction with oigon tides uniquely homologous to the coding sequences of the 5-HT1B/D family (human 5-HTmDa and 5-HT1DP; rat 5-HTo The 5-HT1D serotonin receptor subtype comprises a family of at least two closely related receptors encoded by distinct genes (1, 2) designated 5-HTDDa and 5-HT1DP (2) or 5-HT1D and 5-HT1I (3). Pharmacological evidence supports the existence of prejunctional serotonin (5-hydroxytryptamine, 5-HT) receptors resembling 5-HTj and 5-HT1B on trigeminovascular axons transmitting nociceptive information from guinea pig and rat meninges, respectively (4,5). Serotonin agonists and antimigraine compounds such as sumatriptan and ergot alkaloids bind to these receptor sites to block the development of meningeal neurogenic inflammation and to suppress nociceptive activity within trigeminovascular afferents (6-10).Receptors for the 5-HTlD-like subtype have also been pharmacologically characterized on postjunctional vascular smooth muscle, where they mediate vasoconstriction (11). Recently, Northern blot analyses provided evidence for the selective expression of the 5-HT1Dq receptor gene in pial blood vessels (12). Activation of contractile postjunctional receptors on human coronary and cerebral arteries has been linked to the development of coronary vasospasm (13, 14), myocardial infarction (15), and possibly stroke, complicating the treatment of migraine.Our own studies were undertaken to examine the possible expression of a selective receptor subtype which differentiates the pre-and postjunctional 5-HT1D receptor family. We Human trigeminal ganglia were removed from the skull base of eight individuals 5-18 hr after death. Ganglia were carefully dissected from the surrounding tissue and frozen at -800C.RNA Isolation. Tissue samples were sonicated in GTC buffer [4 M guanidinium thiocyanate/10 mM Tris, pH 7.5/1 mM EDTA/0.5% (wt/vol) N-lauroylsarcosine/1% (vol/vol) 2-mercaptoethanol], and total RNA was extracted as described (16). In brief, the cell lysate was extracted twice with phenol/chloroform and nucleic acids were precipitated in 2-propanol. RNA was resuspended in GTC buffer, precipi- (Fig. 1) (17) and highly homologous to the rat 5-HT1B and human 5-HT1D sequences, but not other 5-HT receptor gene subtypes, including the 5-HT1D pseudogene (18). Primer pairs specific for the human 5-HT1D0 and 5-HTD receptor . §To whom reprint requests should be addressed at: Massachusetts

Release of immunoreactive substance P in the brain stem upon stimulation of the cranial dura mater with low pH – inhibition by the serotonin (5‐HT1) receptor agonist CP 93,129

“…Probably these compounds bind both to the peripheral and central processes of meningeal a erents. Indeed, trigeminal ganglion cells of di erent species including man show gene expression of 5-HT 1 receptors (Adham et al, 1997;Bruinvels et al, 1992;Rebeck et al, 1994), and binding of isotopes of 5-HT 1 receptor agonists ([ 3 H]-sumatriptan and [ 3 H]-zolmitriptan) was autoradiographically detected in the trigeminal nucleus caudalis of the cat (Goadsby & Knight, 1997;Mills & Martin, 1995).…”

5-HT1F Receptor Agonists: A New Treatment Option for Migraine Attacks?

“…Expression of both the 5-HT 1B and the 5-HT 1D receptor have been detected in the trigeminal ganglion 4,18,19 and expression of the 1D receptor subtype has additionally been detected on sensory trigeminal fibers. 5,20 The suggestion has been made that triptans exert their effects by reducing neurogenic inflammation and inhibiting neurotransmitter release mainly through the stimulation of the 5-HT 1D receptor.…”

The 2006 Thomas Willis Lecture

“…In addition to the well-known sites on vascular smooth muscle, we discovered the expression of novel serotonin, or 5-HT, prejunctional receptors on trigeminovascular axons. 7,8 The resulting formulation provided a "road map" that has led to the identification of several novel therapeutic targets. For example, it led to the discovery of a selective agonist activating 5-HT 1F receptors expressed by trigeminovascular axons.…”

“…In addition to the well-known sites on vascular smooth muscle, we discovered the expression of novel serotonin, or 5-HT, prejunctional receptors on trigeminovascular axons. 7,8 Occupancy of these serotonin receptors by abortive drugs inhibits neuropeptide release and by so doing, blocks meningeal and downstream central peptidergic receptor-mediated actions that are important to headache pathogenesis.…”