Detrimental impact of hyperlipidemia on the peripheral nervous system: A novel target of medical epidemiological and fundamental research study

Stearoyl-CoA desaturases sustain cholinergic excitation and copulatory robustness in metabolically aging C. elegansmales

Regulated metabolism is required for behaviors as adults age. To understand how lipid usage affects motor coordination, we studied male Caenorhabditis elegans copulation as a model of energy-intensive behavior. Copulation performance drops after 48 h of adulthood. We found that 12–24 h before behavioral decline, males prioritize exploring and copulation behavior over feeding, suggesting that catabolizing stored metabolites, such as lipids, occurs during this period. Because fat-6/7-encoded stearoyl-CoA desaturases are essential for converting the ingested fatty acids to lipid storage, we examined the copulation behavior and neural calcium transients of fat-6(lf); fat-7(lf) mutants. In wild-type males, intestinal and epithelial fat-6/7 expression increases during the first 48 h of adulthood. The fat-6(lf); fat-7(lf) behavioral and metabolic defects indicate that in aging wild-type males, the increased expression of stearoyl-CoA desaturases in the epidermis may indirectly modulate the levels of EAG-family K⁺ channels in the reproductive cholinergic neurons and muscles.

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Tissue distribution of fat-6-encoded stearoyl-CoA desaturase changes in adulthood

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Markov modeling shows reduced feeding linked with more exploring in day 2 males

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fat-6(lf); fat-7(lf) disrupted behavior can be rescued by epidermal FAT-6

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fat-6(lf); fat-7(lf) alters neural and muscular ERG and EAG K+ channel expression

Association between Statin Use and Sensorineural Hearing Loss in Type 2 Diabetic Patients: A Hospital-Based Study

Statins have emerged as protective agents against sensorineural hearing loss (SNHL) associated with dyslipidemia, but the effects of statins on SNHL are not consistent. The purpose of this study was to investigate the association between statin use and the risk of SNHL using a hospital cohort. This nested case-control study included type 2 diabetic patients over the age of 18 years without a history of hearing loss. Of these, 1379 patients newly diagnosed with SNHL or tinnitus were classified as cases, and 5512 patients matched to the cases based on age, sex, and index year were classified as controls. Chi-squared tests were used to compare categorical variables between the two groups. Odds ratios (ORs) and adjusted odds ratios (AOR) were calculated from univariate and multivariable unconditional logistic regression analyses, respectively. There was a significant difference in the prevalence of statin use between the cases and controls (53.7% vs. 61.2%, respectively; p < 0.001). The use of statins in type 2 diabetic patients significantly reduced the risk of SNHL or tinnitus by 24.8% (95% CI 14.2–34.1%, p < 0.001) after controlling for confounders. Similar results were found for the association between statin use and SNHL (AOR = 0.706; 95% CI 0.616–0.811, p < 0.001). The protective effects of statins against SNHL were consistent regardless of age and sex. The use of statins for type 2 diabetic patients was significantly associated with a reduced risk of SNHL, regardless of age and sex. Further studies are needed, especially large cohort studies, to evaluate the long-term protective effects of statins.

Non-glucose risk factors in the pathogenesis of diabetic peripheral neuropathy

In this review, we consider the diverse risk factors in diabetes patients beyond hyperglycemia that are being recognized as contributors to diabetic peripheral neuropathy (DPN). Interest in such alternative mechanisms has been encouraged by the recognition that neuropathy occurs in subjects with metabolic syndrome and pre-diabetes and by the reporting of several large clinical studies that failed to show reduced prevalence of neuropathy after intensive glucose control in patients with type 2 diabetes. Animal models of obesity, dyslipidemia, hypertension, and other disorders common to both pre-diabetes and diabetes have been used to highlight a number of plausible pathogenic mechanisms that may either damage the nerve independent of hyperglycemia or augment the toxic potential of hyperglycemia. While pathogenic mechanisms stemming from hyperglycemia are likely to be significant contributors to DPN, future therapeutic strategies will require a more nuanced approach that considers a range of concurrent insults derived from the complex pathophysiology of diabetes beyond direct hyperglycemia.

Statins and Neuropathic Pain: A Narrative Review

The frequently prescribed drug class of statins have pleiotropic effects and have been implicated in neuropathic pain syndromes. This narrative review examines studies of statin-induced neuropathic pain which to date have been conducted only in animal models. However, the pathophysiology of diabetic neuropathy in humans may shed some light on the etiology of neuropathic pain. Statins have exhibited a paradoxical effect in that statins appear to reduce neuropathic pain in animals but have been associated with neuropathic pain in humans. While there are certain postulated mechanisms offering elucidation as to how statins might be associated with neuropathic pain, there is, as the American Heart Association stated, to date no definitive association between statins and neuropathic pain. Statins are important drugs that reduce cardiovascular risk factors and should be prescribed to appropriate patients with these risk factors but some of this population is also at elevated risk for neuropathic pain from other causes.

Nebivolol, a β-blocker abrogates streptozotocin-induced behavioral, biochemical, and neurophysiological deficit by attenuating oxidative-nitrosative stress: a possible target for the prevention of diabetic neuropathy

Metabolic abnormalities including hyperglycemia, hyperlipidemia, and oxidative-nitrosative stress are involved in the progression of diabetic neuropathy. In the present study, we targeted oxidative-nitrosative stress using nebivolol, a β₁-receptor antagonist with vasodilator and antioxidant property, to evaluate its neuroprotective effect in streptozotocin-induced diabetic neuropathy in rats. Diabetic neuropathy develops within 4-6 weeks after administration of streptozotocin (55 mg/kg, i.p.). Therefore, after confirmation of diabetes, subtherapeutic doses of nebivolol (1 and 2 mg/kg, p.o./day) were given to diabetic rats for 8 weeks. Nebivolol treatment significantly improved thermal hyperalgesia, grip strength, and motor coordination. Nebivolol also reduced levels of malondialdehyde, tumor necrosis factor-α, and nitrite in diabetes. Moreover, nebivolol increased the levels of superoxide dismutase and catalase in sciatic nerve homogenate of diabetic rats. Further, nebivolol exerted positive effects on lipid profile, sciatic nerve's morphological changes and nerve conduction velocity in diabetic rats. Results of the present study suggest the neuroprotective effect of nebivolol through its antioxidant, nitric oxide-potentiating, and antihyperlipidemic activity.