The high throughput screening of neuropeptide FF2 receptor ligands from Korean herbal plant extracts

Neuropeptide FF and Its Receptors: Therapeutic Applications and Ligand Development

The endogenous neuropeptide FF (NPFF) and its two cognate G protein-coupled receptors, Neuropeptide FF Receptors 1 and 2 (NPFFR1 and NPFFR2), represent a relatively new target system for many therapeutic applications including pain regulation, modulation of opioid side effects, drug reward, anxiety, cardiovascular conditions, and other peripheral effects. Since the cloning of NPFFR1 and NPFFR2 in 2000, significant progress has been made to understand their pharmacological roles and interactions with other receptor systems, notably the opioid receptors. A variety of NPFFR ligands with different mechanisms of action (agonists or antagonists) have been discovered although with limited subtype selectivities. Differential pharmacological effects have been observed for many of these NPFFR ligands, depending on assays/models employed and routes of administration. In this Perspective, we highlight the therapeutic potentials, current knowledge gaps, and latest updates of the development of peptidic and small molecule NPFFR ligands as tool compounds and therapeutic candidates.

RF-amide neuropeptides and their receptors in Mammals: Pharmacological properties, drug development and main physiological functions

RF-amide neuropeptides, with their typical Arg-Phe-NH2 signature at their carboxyl C-termini, belong to a lineage of peptides that spans almost the entire life tree. Throughout evolution, RF-amide peptides and their receptors preserved fundamental roles in reproduction and feeding, both in Vertebrates and Invertebrates. The scope of this review is to summarize the current knowledge on the RF-amide systems in Mammals from historical aspects to therapeutic opportunities. Taking advantage of the most recent findings in the field, special focus will be given on molecular and pharmacological properties of RF-amide peptides and their receptors as well as on their implication in the control of different physiological functions including feeding, reproduction and pain. Recent progress on the development of drugs that target RF-amide receptors will also be addressed.

Traditional medicine Taeeumjowitangkagambang exerts antiobesity and hypolipidemic effects via antioxidant enzyme enhancement

Taeeumjowitangkagambang (ETJKB) is a traditional Korean medicine that has been clinically used for obesity with little mechanistic understanding. The present study investigated antiobesity and hypolipidemic effects of ETJKB in high fat diet fed rats as well as a 3T3-L1 pre-adipocyte differentiation model. ETJKB significantly inhibited the lipidogenesis in 3T3-L1 adipocytes in a concentration-dependent manner as well as reduced the cellular adipokine leptin level. Daily oral gavage of ETJKB to rats fed a high fat diet significantly attenuated body weight gain and abdominal and epididymal fat weights. ETJKB treatment also reduced the levels of total cholesterol, low density lipoprotein (LDL) and triglyceride as well as increased high density lipoprotein (HDL) in serum compared with the untreated control. Similarly, the ETJKB treatment decreased the levels of total lipid, triglyceride and cholesterol in liver tissue in high fat diet fed rats. Interestingly, ETJKB significantly increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase in liver tissue, while decreasing the hydroxyl radical, thiobarbituric acid reactive substances (TBARS), carbonyl concentration. An improvement of antioxidant enzymes was associated with improved body weight control and healthier lipid profiles and therefore may play an important role in the antiobesity and hypolipidemic effects of ETJKB.

The Korean traditional medicine gyeongshingangjeehwan inhibits adipocyte hypertrophy and visceral adipose tissue accumulation by activating PPARalpha actions in rat white adipose tissues

AIM OF THE STUDY

Gyeongshingangjeehwan (GGEx), which is a polyherbal drug composed of four medicinal plants, has traditionally been used as anti-obesity drug in Korean local clinics. Thus, we investigated the effects of GGEx on visceral adiposity and examined whether adipose peroxisome proliferator-activated receptor alpha (PPARalpha) activation is involved in this process.

MATERIALS AND METHODS

After Obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats and differentiated 3T3-L1 adipocytes were treated with GGEx, we studied the effects of GGEx on not only visceral white adipose tissue (WAT) mass and adipocyte size, but also the expression of adipocyte marker and PPARalpha target genes.

RESULTS

Administration of GGEx to obese rats for 8 weeks decreased visceral WAT weight by 30% and the size of adipocytes in mesenteric WAT by 31% without weight changes of other organs. Concomitantly, GGEx increased mRNA levels of PPARalpha target genes responsible for fatty acid beta-oxidation in mesenteric WAT whereas decreased mRNA expression of adipocyte markers, such as PPARgamma, aP2 and leptin. Serological studies demonstrated that plasma levels of free fatty acids and triglycerides as well as insulin and glucose were decreased following GGEx treatment. Consistent with the in vivo data, GGEx increased PPARalpha reporter gene activity and induced the mRNA expression of PPARalpha target genes involved in mitochondrial fatty acid beta-oxidation in 3T3-L1 cells. GGEx also inhibited triglyceride accumulation in these cells.

CONCLUSION

These results suggest that GGEx promotes the reductions in visceral fat mass and adipocyte size in obese animals, and that this event may be mediated by adipose PPARalpha activation.

The interdependence between screening methods and screening libraries

The most common methods for discovery of chemical compounds capable of manipulating biological function involves some form of screening. The success of such screens is highly dependent on the chemical materials - commonly referred to as libraries - that are assayed. Classic methods for the design of screening libraries have depended on knowledge of target structure and relevant pharmacophores for target focus, and on simple count-based measures to assess other properties. The recent proliferation of two novel screening paradigms, structure-based screening and high-content screening, prompts a profound rethink about the ideal composition of small-molecule screening libraries. We suggest that currently utilized libraries are not optimal for addressing new targets by high-throughput screening, or complex phenotypes by high-content screening.