The effect of dihydropyrazines on lipopolysaccharide-stimulated human hepatoma HepG2 cells via regulating the TLR4-MyD88-mediated NF-κB signaling pathway.

Dihydropyrazines (DHPs), including 3-hydro-2,2,5,6-tetramethylpyrazine (DHP-3), are glycation products that are spontaneously generated in vivo and ingested via food. DHPs generate various radicals and reactive oxygen species (ROS), which can induce the expression of several antioxidant genes in HepG2 cells. However, detailed information on DHP-response pathways remains elusive. To address this issue, we investigated the effects of DHP-3 on the nuclear factor-κB (NF-κB) pathway, a ROS-sensitive signaling pathway. In lipopolysaccharide-stimulated (LPS-stimulated) HepG2 cells, DHP-3 decreased phosphorylation levels of inhibitor of NF-κB (IκB) and NF-κB p65, and nuclear translocation of NF-κB p65. In addition, DHP-3 reduced the expression of Toll-like receptor 4 (TLR4) and the adaptor protein myeloid differentiation primary response gene 88 (MyD88). Moreover, DHP-3 suppressed the mRNA expression of tumor necrosis factor-alpha (TNFα), and interleukin-1 beta (IL-1ß). Taken together, these results suggest that DHP-3 acts as a negative regulator of the TLR4-MyD88-mediated NF-κB signaling pathway.

Getting to the Heart of the Matter: Migraine, Triptans, DHE, Ditans, CGRP Antibodies, First/Second-Generation Gepants, and Cardiovascular Risk.

PREMISE: The science of migraine pathophysiology has advanced significantly since the 1930's. Imaging techniques, neurochemical analysis, clinical trials, and the clinical experience of providers treating migraine patients have not only sharpened our understanding of the disease, but have also led to the development of novel neural-based targets. Targeted therapies such as calcitonin gene-related peptide (CGRP) antibodies and "Second Generation" CGRP receptor antagonists (Gepants) have not only demonstrated efficacy, but have not resulted in any significant cardiovascular nor other serious adverse events. "First Generation" Gepants were associated with liver toxicity. PROBLEM: Triptans and dihydroergotamine (DHE) are contraindicated in patients with hemiplegic and basilar migraine based on theories of migraine pathophysiology from the 1930s. While our understanding of migraine has evolved substantially, perceived concerns of safety from almost a century ago continue to preclude their use in certain patient populations. POTENTIAL SOLUTION: While migraine aura was once thought to be primarily due to vasoconstriction, current evidence debunks this concept. For instance, hemiplegic migraine is the consequence of genetic mutations resulting in channelopathies without evidence of cerebral ischemia or infarction. Evidence of basilar artery constriction as postulated in basilar migraine is also lacking. This recognition has led the International Headache Society to rename basilar-type migraine to migraine with brainstem aura. The following discussion reviews current literature with respect to migraine as a neuronal disorder, as well as the published data on the safety of triptans, DHE, Ditans (a novel class of 5-HT1f receptor agonists), CGRP antibodies, and Gepants.

Environmental and drug factors in hepatic porphyria.

Numerous drugs and environmental chemicals are capable of influencing the clinical expression of human hepatic porphyria primarily by interfering with the orderly regulation of heme synthesis in the liver. Some agents trigger the disease in otherwise normal individuals whereas others exacerbate an underlying genetic abnormality leading to disease expression. In both instances careful avoidance of exposure to these drugs and chemicals can largely prevent the development of manifest disease. The mechanisms whereby these agents impair the normal regulation of hepatic heme synthesis have been carefully studied in recent years and have provided valuable new insights into this form of drug-induced hepatotoxicity.

The effect of environmental lighting on porphyrin hepatic metabolism in the rat.

It has been shown that light may stimulate hepatic porphyria in the rat. This is evidently due to a neuro-endocrine pathway involving retina, nerve pathways in the brain and including the sympathetic chain, the pineal gland and the gonads. This light effect in porphyria appears to be via a circadian rhythm in the liver.

The use of the rat in the experimental investigation of the porphyrias.

The patterns of urinary porphyria excretion and hepatic porphyrin accumulation in hexachlorobenzene-treated rats is similar to that observed in overt porphyria cutanea tarda and may be attributed to a decrease in activity of hepatic uroporphyrinogen (UROGEN) decarboxylase. The 3.5 diethoxycarbonyl-1,4-dihydrocollidine (DDC)-treated rat has been evaluated as a model to test the porphyrinogenicity of drugs.