F. Mangin et al. / Bioorg. Med. Chem. Lett. 22 (2012) 4550–4554
4553
Table 3
In vitro binding profile of target compounds, 3e and 3i, in comparison with WAY-100635a,b,c
Compd
5-HT1A
5-HT2A
5-HT2B
5-HT7
a1A
a1B
D4
WAY-100635(3a)
3e
3i
0.6 (2.2)d
1.85
0.69
6260d
180
54
24d
327
105
>10,000d
198
60
20d
584
39
322d
1051
296
16d
246
55
a
b
The primary testing of the compounds on a number of receptors (serotonin receptor subtypes: 5-HT1B, 5-HT1D, 5ht1e, 5-HT2C, 5-HT3, 5-ht5a, 5-HT6; adrenoceptor subtypes:
2B, b1, b2, b3; benzodiazepine rat brain site; dopamine receptor subtype D1, D5; dopamine transporter (DAT); GABAA; H3; muscarinic receptor subtypes M1–5) showed
M). On other receptors (dopamine receptor subtypes D2 and D3; sigma receptor subtypes 1 and 2) where the compounds showed >50% inhibition at
M the Ki values were at least a factor of 100 greater than those for the 5-HT1A receptor.
a2A, a
<50% inhibition at 10
l
r
r
10
l
c
Results are presented as apparent equilibrium constant (Ki) in nM and are the mean of two experiments.
d
shown). Similarly to WAY-100635, both compounds behave as
neutral antagonists in this pharmacological procedure.
In conclusion, with these chemical modifications, we have iden-
tified substitutions that increase selectivity for 5-HT1A versus D4
receptors and also versus other receptors, such as the adrenoceptor
subtypes. In addition, the analogues retain WAY-100635-like
5-HT1A receptor antagonist activity. Based on the present and
previously reported results, future investigations, including in sil-
ico approaches, should illuminate new chemical modifications for
developing improved pharmacological tools.
Acknowledgments
The technical assistance of S. Counerotte, J. Ghiotto, L. Massotte
and J. Widart for elemental analyses, NMR spectra, electrophysio-
logical recordings and mass spectra, respectively, is gratefully
acknowledged. This study is supported in part by grants of the
Fonds de la Recherche Scientifique-FNRS (F.R.S.-FNRS) and the
Fonds Spéciaux pour la Recherche of the University of Liège
(Belgium). J.-F.L. is Research Director of the F.R.S.-FNRS. B.J. was
supported by a Research Student fellowship from the Faculty of
Medicine of the University of Liège. Extended radioligand binding
assays on 3e and 3i were performed by the NIMH Psychoactive
Drug Screening Program Contract to BLR.
Figure 2. In vitro extracellular recording of a dorsal raphe serotonergic neuron. The
inhibitory effect of 8-OH-DPAT is reversed by the simultaneous application of 3i.
values equal approximately to 11, 132 and 80 for WAY-100635, 3e
and 3i, respectively. Nevertheless, in terms of selectivity for 5-HT1A
versus D4 receptors, 3e and 3i appeared more discriminating than
did WAY-100635, with a selectivity ratio increasing from 4 to 11
and from 4 to 4.5, respectively. Otherwise, compound 3e has lower
Supplementary data
affinity for several receptors (a1A, a1D, 5-HT2B) than does WAY-
100635. However, an increase in 5-HT7 receptor affinity is ob-
served for both compounds (3e, 3i), but it remains approximately
60–120 times lower than the affinity for the 5-HT1A receptor. Inter-
estingly, it appears that the THP analogue 3i possesses a higher
affinity for all receptors than does 3e. An increase in affinity for
5-HT1A receptors was previously observed10 and discussed14 in an-
other series.
Furthermore, the two most selective compounds (3e, 3i) were
evaluated in an electrophysiological procedure to confirm their
5-HT1A receptor antagonism. It is well known that the firing rate
of dorsal raphe serotonergic neurons is inhibited by 5-HT1A ago-
nists such as 8-OH-DPAT,17 and that this effect is blocked or
reversed by 5-HT1A antagonists such as WAY-100635.1 In this
work, dorsal raphe serotonergic neurons were recorded in rat brain
slices, and the ability of the two compounds to reverse the effect of
8-OH-DPAT was evaluated. Superfusion of 8-OH-DPAT (20 nM) in-
duced a progressive decrease of the firing rate of dorsal raphe sero-
tonergic neurons. A complete inhibition of firing was observed
after 5–10 min. Compounds (3e) and (3i) both reversed the inhib-
itory effect of 8-OH-DPAT when superfused at a concentration of
100 nM. At this concentration, reversal ranged from 44% to 73%
for compound (3e) (n = 3) and from 44% to 99% for compound
(3i) (n = 3) (Fig. 2). Furthermore, when superfused alone at concen-
Supplementary data associated with this article can be found, in
References and notes
1. Forster, E. A.; Cliffe, I. A.; Bill, D. J.; Dover, G. M.; Jones, D.; Reilly, Y.; Fletcher, A.
Eur. J. Pharmacol. 1995, 281, 81.
2. Chemel, B. R.; Roth, B. L.; Armbruster, B.; Watts, V. J.; Nichols, D. E.
Psychopharmacology 2006, 188, 244.
3. Marona-Lewicka, D.; Nichols, D. E. Behav. Pharmacol. 2009, 20, 114.
4. Martel, J. C.; Leduc, N.; Ormiere, A. M.; Faucillon, V.; Danty, N.; Culie, C.; Cussac,
D.; Newman-Tancredi, A. Eur. J. Pharmacol. 2007, 574, 15.
5. Marchais-Oberwinkler, S.; Nowicki, B.; Pike, V. W.; Halldin, C.; Sandell, J.; Chou,
Y. H.; Gulyas, B.; Brennum, L. T.; Farde, L.; Wikström, H. V. Bioorg. Med. Chem.
2005, 13, 883.
6. Childers, W. E., Jr.; Havran, L. M.; Asselin, M.; Bicksler, J. J.; Chong, D. C.; Grosu,
G. T.; Shen, Z.; Abou-Gharbia, M. A.; Bach, A. C., 3rd; Harrison, B. L.; Kagan, N.;
Kleintop, T.; Magolda, R.; Marathias, V.; Robichaud, A. J.; Sabb, A. L.; Zhang, M.
Y.; Andree, T. H.; Aschmies, S. H.; Beyer, C.; Comery, T. A.; Day, M.; Grauer, S.
M.; Hughes, Z. A.; Rosenzweig-Lipson, S.; Platt, B.; Pulicicchio, C.; Smith, D. E.;
Sukoff-Rizzo, S. J.; Sullivan, K. M.; Adedoyin, A.; Huselton, C.; Hirst, W. D. J. Med.
Chem. 2010, 53, 4066.
7. Khatri, M.; Rai, S. K.; Alam, S.; Vij, A.; Tiwari, M. Bioorg. Med. Chem. 2009, 17, 1890.
8. Al Hussainy, R.; Verbeek, J.; van der Born, D.; Booij, J.; Herscheid, J. K. Eur. J. Med.
Chem. 2011, 46, 5728.
9. Al Hussainy, R.; Verbeek, J.; van der Born, D.; Braker, A. H.; Leysen, J. E.; Knol, R.
J.; Booij, J.; Herscheid, J. K. J. Med. Chem. 2011, 54, 3480.
10. Graulich, A.; Léonard, M.; Résimont, M.; Huang, X. P.; Roth, B. L.; Liégeois, J.-F.
Aust. J. Chem. 2010, 63, 56.
trations ranging from 1 nM to 1
lM, neither compound induced an
inhibition of firing, confirming a lack of agonist activity (data not