The neuroprotective effects of micronized PEA (PEA‐m) formulation on diabetic peripheral neuropathy in mice

Palmitoylethanolamide (PEA), the naturally occurring amide of palmitic acid and ethanolamine, reduces pain and inflammation through an as-yet-uncharacterized mechanism. Here, we identify the nuclear receptor peroxisome proliferator-activated receptor-alpha (PPAR-alpha) as the molecular target responsible for the anti-inflammatory properties of PEA. PEA selectively activates PPAR-alpha in vitro with an EC(50) value of 3.1 +/- 0.4 microM and induces the expression of PPAR-alpha mRNA when applied topically to mouse skin. In two animal models, carrageenan-induced paw edema and phorbol ester-induced ear edema, PEA attenuates inflammation in wild-type mice but has no effect in mice deficient in PPAR-alpha. The natural PPAR-alpha agonist oleoylethanolamide (OEA) and the synthetic PPAR-alpha agonists GW7647 and Wy-14643 mimic these effects in a PPAR-alpha-dependent manner. These findings indicate that PPAR-alpha mediates the anti-inflammatory effects of PEA and suggest that this fatty-acid ethanolamide may serve, like its analog OEA, as an endogenous ligand of PPAR-alpha.

Palmitoylethanolamide (PEA) is a pleiotropic lipid mediator with established anti-inflammatory and anti-hyperalgesic activity. Ultramicronized PEA (PEA-um) has superior oral efficacy compared to naïve (non-micronized) PEA. The aim of the present study was two-fold: (1) to evaluate whether oral PEA-um has greater absorbability compared to naïve PEA, and its ability to reach peripheral and central tissues under healthy and local inflammatory conditions (carrageenan paw edema); (2) to better characterize the molecular pathways involved in PEA-um action, particularly at the spinal level. Rats were dosed with 30 mg/kg of [13C]4-PEA-um or naïve [13C]4-PEA by oral gavage, and [13C]4-PEA levels quantified, as a function of time, by liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry. Overall plasma levels were higher in both healthy and carrageenan-injected rats administered [13C]4-PEA-um as compared to those receiving naïve [13C]4-PEA, indicating the greater absorbability of PEA-um. Furthermore, carrageenan injection markedly favored an increase in levels of [13C]4-PEA in plasma, paw and spinal cord. Oral treatment of carrageenan-injected rats with PEA-um (10 mg/kg) confirmed beneficial peripheral effects on paw inflammation, thermal hyperalgesia and tissue damage. Notably, PEA-um down-regulated distinct spinal inflammatory and oxidative pathways. These last findings instruct on spinal mechanisms involved in the anti-hyperalgesic effect of PEA-um in inflammatory pain.

Vascular dementia (VaD), the second most common cause of cognitive impairment in the population, is a disease that results from reduction in regional cerebral blood flow and involves oxidative stress and inflammation. Co-ultramicronized PEALut (co-ultra PEALut) is a new compound with beneficial effects, which include anti-inflammatory and antioxidant properties. Recently, co-ultraPEALut has been shown to exhibit neuroprotective effects in models of Parkinson’s disease, cerebral ischemia and Alzheimer’s disease. However, its effects on VaD remain unknown. Therefore, the purpose of the present study was to highlight the potential neuroprotective actions of co-ultraPEALut containing N-palmitoylethanolamine (PEA) and the antioxidant flavonoid luteolin (Lut) (10:1 by mass) in a mouse model of VaD induced by bilateral carotid arteries occlusion. At 24 h after VaD induction, mice were orally treated with 1 mg/kg co-ultraPEALut daily for 15 days. On the 15th day, brain tissues were processed for histological, immunohistochemical, Western blot, and immunofluorescent analysis. Our results clearly demonstrate that co-ultraPEALut improved learning, memory ability, locomotor activity, and the reciprocal social interaction. In addition, the mice subjected to VaD and treated with the co-ultraPEALut showed a reorganization of CA1 and CA3 regions of the hippocampus and restored the number of hippocampal neurons as evidenced by NeuN expression, a specific marker of neurons. Furthermore following carotid arteries ligation, mice treated with co-ultraPEALut showed a modification of proinflammatory, proapoptotic proteins and of oxidative stress as evidenced by the expression of IκB-α, NF-κB p65, Bax, Bcl-2, inducible nitric oxide synthase, and cyclooxygenase-2. In order, co-ultraPEALut treatment restored VaD-induced loss of brain-derived neurotrophic factor and neurotrophins 3 (NT-3) expression in mice. These results confirmed that the neuroprotective effects of co-ultraPEALut were associated with its anti-inflammatory and antioxidant properties.