Opioid receptors x H1 receptor

Many structures of the central nervous system recruit different neurotransmitters in pain processing. This study focused on the contribution of histamine and its H1 receptors in the ventral pallidum (VP) in mediating pain-triggered behaviors. Intra-VP microinjection of histamine and 2-pyridylethylamine (2-PEA, a histamine H1 receptor agonist) at the same doses of 0.5 and 1 µg/200 nl reduced both the first and second phases of licking/biting duration as well as flinching number induced by intra-plantar (ipl) injection of formalin (2.5%, 50 µl). Premicroinjection of mepyramine (a histamine H1 antagonist, 2 µg/200 nl) into the VP antagonized the suppressive effects of 1 µg/200 nl histamine and 2-PEA on licking/biting and flinching behaviors. The possible mechanisms of the above-mentioned pain-reducing effects were followed by intra-VP and intrathecal administration of naloxone (an opioid receptor antagonist). Naloxone (2 µg/200 nl) preadministration into the VP inhibited attenuating effects of histamine and 2-PEA on both the licking/biting and flinching behaviors, whereas intrathecal injection of naloxone only inhibited their suppressing effects on flinching behavior. None of the treatments used in this study altered the animal's motor activity. The obtained results may reveal the role of histamine and its activated H1 receptor in the VP in suppressing the pain behaviors caused by formalin. Opioid receptors in the VP and spinal cord may contribute to these functions.

Sheng-Ji Hua-Yu (SJHY) formula has been proved to reduce the severity of diabetic wound healing without significant adverse events in our previous clinical trials. However, based on multi-target characteristics, the regulatory network among herbs, ingredients, and hub genes remains to be elucidated. The current study aims to identify the biomarkers of the SJHY formula for the treatment of diabetic wound healing. First, a network of components and targets for the SJHY formula was constructed using network pharmacology. Second, the ClusterONE algorithm was used to build a modular network and identify hub genes along with kernel pathways. Third, we verified the kernel targets by molecular docking to select hub genes. In addition, the biomarkers of the SJHY formula were validated by animal experiments in a diabetic wound healing mice model. The results revealed that the SJHY formula downregulated the mRNA expression of Cxcr4 , Oprd1 , and Htr2a , while upregulated Adrb2 , Drd , Drd4 , and Hrh1 . Besides, the SJHY formula upregulated the kernel pathways, neuroactive ligand-receptor interaction, and cAMP signaling pathway in the skin tissue homogenate of the diabetic wound healing mice model. In summary, this study identified the potential targets and kernel pathways, providing additional evidence for the clinical application of the SJHY formula for the treatment of diabetic wound healing.

To investigate large library docking's ability to find molecules with joint activity against on-targets and selectivity versus antitargets, the dopamine D ₂ and serotonin 5-HT _2A receptors were targeted, seeking selectivity against the histamine H ₁ receptor. In a second campaign, κ-opioid receptor ligands were sought with selectivity versus the μ-opioid receptor. While hit rates ranged from 40% to 63% against the on-targets, they were just as good against the antitargets, even though the molecules were selected for their putative lack of binding to the off-targets. Affinities, too, were often as good or better for the off-targets. Even though it was occasionally possible to find selective molecules, such as a mid-nanomolar D ₂ /5-HT _2A ligand with 21-fold selectivity versus the H ₁ receptor, this was the exception. Whereas false-negatives are tolerable in docking screens against on-targets, they are intolerable against antitargets; addressing this problem may demand new strategies in the field.