Selective activation of dopamine D1 receptors (D1Rs) has been pursued for 40 years as a therapeutic strategy for neurologic and psychiatric diseases due to the fundamental role of D1Rs in motor function, reward processing, and cognition. All known D1R-selective agonists are catechols, which are rapidly metabolized and desensitize the D1R after prolonged exposure, reducing agonist response. As such, drug-like selective D1R agonists have remained elusive. Here we report a novel series of selective, potent non-catechol D1R agonists with promising in vivo pharmacokinetic properties. These ligands stimulate adenylyl cyclase signaling and are efficacious in a rodent model of Parkinson's disease after oral administration. They exhibit distinct binding to the D1R orthosteric site and a novel functional profile including minimal receptor desensitization, reduced recruitment of β-arrestin, and sustained in vivo efficacy. These results reveal a novel class of D1 agonists with favorable drug-like properties, and define the molecular basis for catechol-specific recruitment of β-arrestin to D1Rs.

Fibroblast growth factor 21 (FGF21) is a hormone secreted by the liver in response to metabolic stress. In addition to its well-characterized effects on energy homeostasis, FGF21 has been shown to increase water intake in animals. In this study, we sought to further explore the effects of FGF21 on fluid homeostasis in rats. A single dose of a long-acting FGF21 analog, PF-05231023, significantly increased water consumption, which was accompanied by an elevation in urine output that appeared prior to a significant change in water intake. We observed that FGF21 rapidly and significantly increased heart rate and blood pressure in telemeter-implanted rats, before changes in urine output and water intake were observed. Our data suggest that sympathetic activation may contribute to the pathogenesis by which FGF21 increases blood pressure as the baroreceptor unloading induced reflex tachycardia was significantly elevated in FGF21-treated animals. However, FGF21 was still capable of causing hypertension in animals in which approximately 40% of the sympathetic post-ganglionic neurons were ablated. Our data suggest that FGF21-induced water intake is in fact secondary to diuresis, which we propose to be a compensatory mechanism engaged to alleviate the acute hypertension caused by FGF21.

Casein kinase 1 delta (CK1δ) and casein kinase 1 epsilon (CK1ε) inhibitors are potential therapeutic agents for a range of psychiatric disorders. The feasibility of developing a CNS kinase inhibitor has been limited by an inability to identify safe brain-penetrant compounds with high kinome selectivity. Guided by structure-based drug design, potent and selective CK1δ/ε inhibitors have now been identified that address this gap, through the design and synthesis of novel 4-[4-(4-fluorophenyl)-1-(piperidin-4-yl)-1H-imidazol-5-yl]pyrimidin-2-amine derivatives. PF-5006739 (6) possesses a desirable profile, with low nanomolar in vitro potency for CK1δ/ε (IC50 = 3.9 and 17.0 nM, respectively) and high kinome selectivity. In vivo, 6 demonstrated robust centrally mediated circadian rhythm phase-delaying effects in both nocturnal and diurnal animal models. Further, 6 dose-dependently attenuated opioid drug-seeking behavior in a rodent operant reinstatement model in animals trained to self-administer fentanyl. Collectively, our data supports further development of 6 as a promising candidate to test the hypothesis of CK1δ/ε inhibition in treating multiple indications in the clinic.

Murine models are increasingly used for investigations of sleep, yet no previous studies have characterized cholinergic activation of guanine nucleotide binding proteins (G proteins) in mouse brainstem nuclei known to regulate sleep. This study used in vitro [(35)S]guanylyl-5'-O-(gamma-thio)-triphosphate ([(35)S]GTPgammaS) autoradiography to test the hypothesis that muscarinic cholinergic receptors activate G proteins in C57BL/6J (B6) mouse brainstem. The nuclei studied are homologous to those known in rat and cat to modulate sleep and nociception. In B6 mouse, carbachol significantly increased specific binding of [(35)S]GTPgammaS in the pontine reticular nucleus, caudal part (79%); pontine reticular nucleus, oral part (131%); laterodorsal tegmental nucleus (56%); pedunculopontine tegmental nucleus (86%); dorsal raphe nucleus (53%); dorsal medial periaqueductal gray (54%); and ventrolateral periaqueductal gray (52%) when compared with basal binding. Carbachol-induced G protein activation was concentration-dependent and blocked by atropine, demonstrating mediation by muscarinic receptors. G protein activation by carbachol was heterogeneous across B6 mouse brainstem nuclei. Comparison of [(35)S]GTPgammaS binding between mouse and rat revealed different magnitudes of G protein activation in the pontine reticular formation. In the same pontine reticular formation area of B6 mouse where in vitro treatment with carbachol activates G proteins, in vivo microinjection of cholinomimetics causes a rapid eye movement sleep-like state. These data provide the first direct measurement of muscarinic receptor-activated G proteins in B6 mouse brainstem nuclei known in other species to regulate sleep.

Abstract. Amyloid-β (Aβ) overproduction and dendrite arbor atrophy are hallmarks of Alzheimer's disease. The RhoA GTPase (Rho) signals through Rho kinase (ROCK) to control cytoskeletal dynamics and regulate neuron structure. Hyperactive Rho signaling destabilizes neurons leading to dendritic regression that can be rescued by genetic or pharmacological reduction of ROCK signaling. To understand what effect reduced ROCK signaling has on the dendrite arbors of mice that overproduce Aβ, we administered the ROCK inhibitor fasudil to AβPP/PS1 transgenic mice. We report that increased dendrite branching occurs in AβPP/PS1 mice and that fasudil promotes lengthening of the dendrite arbors of CA1 pyramidal neurons.

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In mammals, the master circadian clock synchronizes daily rhythms of physiology and behavior with the day–night cycle. Failure of synchrony, which increases the risk for numerous chronic diseases, can be treated by phase adjustment of the circadian clock pharmacologically, for example, with melatonin, or a CK 1δ/ε inhibitor. Here, using in silico experiments with a systems pharmacology model describing molecular interactions, and pharmacokinetic and behavioral experiments in cynomolgus monkeys, we find that the circadian phase delay caused by CK 1δ/ε inhibition is more strongly attenuated by light in diurnal monkeys and humans than in nocturnal mice, which are common preclinical models. Furthermore, the effect of CK 1δ/ε inhibition strongly depends on endogenous PER 2 protein levels, which differs depending on both the molecular cause of the circadian disruption and the patient's lighting environment. To circumvent such large interindividual variations, we developed an adaptive chronotherapeutics to identify precise dosing regimens that could restore normal circadian phase under different conditions. Our results reveal the importance of photosensitivity in the clinical efficacy of clock‐modulating drugs, and enable precision medicine for circadian disruption.

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