Nerve growth factor concentrations in the synovial fluid from healthy dogs and dogs with secondary osteoarthritis.

OBJECTIVE: To measure the concentrations of nerve growth factor (NGF) in the synovial fluid from normal dogs and dogs with osteoarthritis (OA) secondary to common joint disorders. METHODS: Nerve growth factor synovial concentrations were measured by ELISA assay in 50 dogs divided into three groups: 12 healthy, 16 affected by acute lameness within seven days before enrolment, and 22 with chronic lameness persisting by more than one month before enrolment and accompanied by radiological signs of OA. Both acute and chronic lameness were secondary to orthopaedic diseases involving the shoulder, elbow and stifle joints. Nerve growth factor synovial concentrations were compared between means for healthy and acute groups and between the three groups using an F-test. Significance level was set at p <0.05. RESULTS: Nerve growth factor was detected in all canine synovial fluid samples. However, the mean synovial NGF concentration of healthy dogs (3.65 ± 2.18 pg/ml) was not significantly different from the mean value in dogs with acute lameness (6.45 ± 2.45 pg/ml) (p = 0.79). Conversely, the mean synovial NGF concentration in dogs with chronic lameness (20.19 ± 17.51 pg/ml) was found to be significantly higher than that found in healthy dogs (p <0.01). CLINICAL SIGNIFICANCE: This study demonstrates for the first time the presence of NGF in canine synovial fluid and its increased concentrations in dogs with chronic lameness compared to healthy dogs and dogs with acute lameness. The association between chronic lameness and raised synovial concentrations may suggest an involvement of NGF in OA inflammation and chronic pain.

Effects of palmitoylethanolamide on immunologically induced histamine, PGD2 and TNFalpha release from canine skin mast cells.

Palmitoylethanolamide (PEA) is an endocannabinoid-like compound and the parent molecule of the aliamide family, a group of fatty acid amides able to act through the down-regulation of mast cell degranulation. PEA has been proven to exert both analgesic and anti-inflammatory activity, and recent studies have shown its ability in reducing clinical symptoms of inflammatory skin diseases, both in humans and in animals. Although its pharmacological efficacy is well known, the mechanism of action of this family of compounds is still unclear. To better understand the cellular effects of aliamides in dogs, canine mast cells freshly isolated from skin biopsies were incubated with IgE-rich serum and were challenged with anti-canine IgE. Histamine, prostaglandin D(2) (PGD(2)) and tumour necrosis factor-alpha (TNFalpha) release was measured in the presence and absence of increasing concentrations of PEA, ranging from 10(-8)M to 10(-5)M. Histamine, PGD(2) and TNFalpha release, immunologically induced by canine anti-IgE, were significantly inhibited in the presence of PEA. The maximum inhibitory effect on histamine release was observed at 3x10(-6)M PEA concentration achieving an inhibition of 54.3+/-5.2%. PGD(2) release was significantly inhibited at 10(-5)M and 10(-6)M PEA concentrations with 25.5+/-10.2% and 14.6+/-5.6% of inhibition, respectively. Finally, PEA inhibited TNFalpha release to 29.2+/-2.0% and 22.1+/-7.2%, at concentrations of 10(-5)M and 3x10(-6)M, respectively. The results obtained in the present study showed the ability of the aliamide PEA to down-modulate skin mast cell activation. Therefore, our findings suggest that the beneficial effect of PEA, observed in inflammation and pain clinical studies, could be due, at least in part, to its ability to inhibit the release of both preformed and newly synthesised mast cell mediators.

Palmitoylethanolamide, endocannabinoids and related cannabimimetic compounds in protection against tissue inflammation and pain: potential use in companion animals.

Endocannabinoids have analgesic/anti-inflammatory properties. The biology of endocannabinoids, their receptors, signalling mechanisms and role in the regulation of physiological processes have been extensively reviewed. This review focuses on the role of palmitoylethanolamide (PEA), an endogenous fatty acid amide analogue of the endocannabinoid anandamide, in tissue protective mechanisms. PEA was first identified almost five decades ago in lipid extracts of various natural products, and its anti-inflammatory and antinociceptive effects were established later. Evidence exists that PEA is synthesised during inflammation and tissue damage and a number of beneficial effects, including the relief of inflammation and pruritus, have been shown to be useful in the control of neurogenic and neuropathic pain. The postulated hypotheses as to the mode of action of PEA include a possible local autacoid-like mediator activity regulating mast-cell activity and putative activation of cannabinoids and vanilloid TRPV1 receptors via "entourage" effects. The large number of scientific investigations into the effects of PEA and PEA-related compounds has given rise to new therapeutic opportunities. In spite of the multitude of therapies currently employed to control inflammation, pain, pruritus and tissue damage, the possibility of using a natural compound, such as PEA to manipulate endogenous protective mechanisms may be considered a beneficial novel therapeutic strategy in veterinary medicine.

Surgery plus chondroprotection for canine cranial cruciate ligament (CCL) rupture: a proton-NMR study.

Rupture of the cranial cruciate ligament (CCL) is one of the most frequent causes of lameness of the rear limb in the dog. Regardless of the type of treatment, CCL rupture inevitably leads to knee osteoarthritis (OA). The purpose of this study was to evaluate the efficacy of associating surgical treatment of spontaneous rupture of the CCL with a chondroprotector, that is called 'supraadditive' because it is formulated to counteract not only chondrodegeneration, but also the oxidative and inflammatory processes of OA. The open-label controlled study used proton NMR spectroscopy to evaluate the synovial fluid of the stifle of 10 dogs with monolateral rupture of the CCL, selected for the study based on specific inclusive criteria. The dogs were assigned randomly into two groups. Five dogs received the supra-additive chondroprotector for 60 days, starting on the day after surgery. Five dogs only underwent surgical reconstruction of the CCL. The results were analysed with the ANOVA unstructured variance matrix-covariance test. The trend over time of the synovial concentration of four metabolites (lactate, alanine, acetyl groups of N-acetylated sugars on glycoproteins and alpha-anomers of glucose) was found to differ to a statistically significant extent between the two groups, suggesting that the supra-additive chondroprotector produces an intra-articular metabolic rebalance. The results support the adjuvant use of the chondroprotector in the management of CCL rupture, in view of its control of the OA changes that accompany this orthopaedic disabling condition.

The mast cell in wound healing.

This review describes the role of the mast cell in the pathobiology of skin healing. After illustrating its main morphofunctional characteristics, with special reference to the dog and cat, we consider the involvement of the mast cell in the various phases of skin repair. With the aid of a wide array of newly formed or preformed mediators released by degranulation, the activated mast cell controls the key events of the healing phases: triggering and modulation of the inflammatory stage, proliferation of connective cellular elements and final remodelling of the newly formed connective tissue matrix. The importance of the mast cell in regulating healing processes is also demonstrated by the fact that a surplus or deficit of degranulated biological mediators causes impaired repair, with the formation of exuberant granulation tissue (e.g. keloids and hypertrophic scars), delayed closure (dehiscence) and chronicity of the inflammatory stage.

Effect of ionophores on lymphocyte cellular metabolism.

The effect of valinomycin, nigericin, gramicidin S and D, A23187 and X537A on respiration and cellular ATP content of rat spleen lymphocytes is presented. It has been found that while valinomycin and nigericin interfere with mitochondrial functions gramicidin D does not show an appreciable effect. These results are explained in terms of different ability of ionophores to re-distribute among intracellular membranes. A23187 and X537A, added with Ca2+, strongly enhanced O2 consumption and reduced cellular ATP content.