JNJ-18038683 is a 5-Hydroxytryptamine Type 7 (5-HT7) receptor antagonist, with pKis of 8.19, 8.20 for rat and human 5-HT7 in HEK293 cells, respectively.
JNJ-18038683 displaced, with high affinity, specific [3H]5-CT binding sites from rat and human 5-HT7 receptor express in HEK293 cells (pKi=8.19±0.02 and 8.20±0.01, respectively). Similar values are obtained on the native 5-HT7 in membranes from rat thalamus (pKi=8.50±0.20). Hill slope values are close to unity, suggesting one-site competitive binding. Antagonist potency of JNJ-18038683 is determined by the measurement of adenylate cyclase activity in HEK293 cells expressing the human or rat 5-HT7 receptor. 5-HT stimulates adenylyl cyclase activity in rat and human 5-HT7/HEK293 cells with a pEC50 of 8.09 and 8.12, respectively. JNJ-18038683 produces a concentration-dependent decrease of 5-HT (100 nM)-stimulated adenylyl cyclase. The pKB values determined for JNJ-18038683 are in good agreement with the corresponding Ki values determined from [3H]5-CT binding studies[1].
JNJ-18038683 dose-dependently suppresses REM sleep mainly during the first 4 h after the treatment. The duration of REM sleep is significantly decreased from the dose of 1 mg/kg onward (P<0.05) during the first 4 h after oral administration. Concomitantly, the REM sleep latency tends to be prolonged in a dose-related manner with a significant increase in REM latency occurring only at the highest dose tested (10 mg/kg; P<0.05). These alterations in REM sleep seem to be state-specific. A separate study is conducted to determine whether repeated administration of JNJ-18038683 for 7 days would result in an adaptation of the EEG sleep response in particular on REM sleep in rats during the course of the treatment and after its discontinuation. JNJ-18038683 is administered for 7 consecutive days (1 mg/kg s.c. per day) at 2 h into the light phase. On the first day of treatment, JNJ-18038683 produces a significant decrease in the time spent in REM sleep during the first 8 h after the injection and a prolongation of the REM sleep latency. The REM sleep latency is increased during the 7-day repeated treatment and is normalized on the first recovery day after cessation of treatment. The significant decrease in REM sleep time is maintained during the 7-day repeated treatment, with a rebound occurring on the first recovery day after treatment discontinuation. The NREM sleep latency and the total NREM sleep time are not affected during the entire treatment[1].
[1]. Bonaventure P, et al. Translational evaluation of JNJ-18038683, a 5-hydroxytryptamine type 7 receptor antagonist, on rapid eye movement sleep and in major depressive disorder. J Pharmacol Exp Ther. 2012 Aug;342(2):429-40.