TABLE 3

Affinity of LDT3, LDT5, and LDT8 for rat 5-HT_1A receptors

Compound	K_{i High,} nM (n)	K_{i Low,} nM (n)	K_{i Low}/K_{i High}
Compound	[pK_i ± SD]	[pK_i ± SD]	[95% C.I.]
LDT3	1.12 (4)	1.73 (3)	1.53
LDT3	[8.95 ± 0.07]***	[8.76 ± 0.19]*	[1.02–2.81]
LDT5	2.51 (4)	6.91 (3)	2.75
LDT5	[8.60 ± 0.05]***	[8.16 ± 0.13]***	[1.68–4.50]
LDT8	0.009 (2)	0.62 (3)	66.9
LDT8	[11.05 ± 0.03]	[9.21 ± 0.07]	[45.0–99.8]
LDT66^{^a}	5.9 (4)	10.2 (4)	1.71
LDT66^{^a}	[8.23 ± 0.3]***	[7.99 ± 0.1]***	[0.32–9.20]
5-HT^{^a}	3.02 (3)	213 (6)	76.8
5-HT^{^a}	[8.52 ± 0.03]	[6.67 ± 0.15]	[40.5–146]

Ki values were determined in competition-binding assays with the agonist [³H]8-OH-DPAT (K_{i High}) or antagonist [³H]p-MPPF (in the presence of high GTP; K_{i Low}), using membrane preparations of rat hippocampus. pK_i values (i.e., −log K_i) were expressed as arithmetic means and S.D. of (n) experiments. The K_{i Low}/K_{i High} ratio is an estimate of the intrinsic activity toward 5-HT_1A receptors, where values significantly higher than 1 indicate agonist activity (5-HT, was used as an example of full agonist), whereas values close to 1 indicate antagonist activity. The 95% confidence intervals (C.I.) of the K_i ratios were calculated as previously described (Noël et al., 2014).
F_3,10 = 1471, P < 0.0001 for K_{i High}. ***P < 0.001 compared with LDT8 (one-way ANOVA for LDTs followed by a post hoc Dunnett’s test).
F_3,9 = 55.97, P < 0.0001 for K_{i Low}. *P < 0.05, ***P < 0.001 compared with LDT8 (one-way ANOVA for LDTs followed by a post hoc Dunnett’s test).
↵^a Data from Chagas-Silva et al., 2014 with permission.