Dietary linoleic acid-induced alterations in pro- and anti-nociceptive lipid autacoids: Implications for idiopathic pain syndromes?

BACKGROUND: Chronic idiopathic pain syndromes are major causes of personal suffering, disability, and societal expense. Dietary n-6 linoleic acid has increased markedly in modern industrialized populations over the past century. These high amounts of linoleic acid could hypothetically predispose to physical pain by increasing the production of pro-nociceptive linoleic acid-derived lipid autacoids and by interfering with the production of anti-nociceptive lipid autacoids derived from n-3 fatty acids. Here, we used a rat model to determine the effect of increasing dietary linoleic acid as a controlled variable for 15 weeks on nociceptive lipid autacoids and their precursor n-6 and n-3 fatty acids in tissues associated with idiopathic pain syndromes. RESULTS: Increasing dietary linoleic acid markedly increased the abundance of linoleic acid and its pro-nociceptive derivatives and reduced the abundance of n-3 eicosapentaenoic acid and docosahexaenoic acid and their anti-nociceptive monoepoxide derivatives. Diet-induced changes occurred in a tissue-specific manner, with marked alterations of nociceptive lipid autacoids in both peripheral and central tissues, and the most pronounced changes in their fatty acid precursors in peripheral tissues. CONCLUSIONS: The present findings provide biochemical support for the hypothesis that the high linoleic acid content of modern industrialized diets may create a biochemical susceptibility to develop chronic pain. Dietary linoleic acid lowering should be further investigated as part of an integrative strategy for the prevention and management of idiopathic pain syndromes.

Medicinas tradicionales andinas y su despenalización: entrevista con Walter Álvarez Quispe / Decriminalizing traditional Andean medicine: an interview with Walter Álvarez Quispe

Walter Álvarez Quispe, terapeuta kallawaya y biomédico especializado en cirugía general y ginecología, presenta la lucha de los terapeutas tradicionales y alternativos por la depenalización de estos sistemas médicos andinos realizada entre 1960 y 1990. Bolivia se torna el primer país en América Latina y el Caribe en despenalizar la medicina tradicional antes de los planteamientos de la Conferencia Internacional sobre Atención Primaria de Salud (Alma-Ata, 1978). Los datos aportados por el entrevistado aseguran que los logros alcanzados, principalmente por los kallawayas, responden a un proyecto propio y autónomo. Estas conquistas no se deben a las políticas oficiales de interculturalidad en salud, aunque busquen atribuirse para sí los logros alcanzados.

Walter Álvarez Quispe, a Kallawaya healer and biomedical practitioner specializing in general surgery and gynecology, presents the struggle of traditional and alternative healers to get their Andean medical systems depenalized between 1960 and 1990. Bolivia was the first country in Latin America and the Caribbean to decriminalize traditional medicine before the proposals of the International Conference on Primary Health Care (Alma-Ata, 1978). The data provided by the interviewee show that the successes achieved, mainly by the Kallawayas, stem from their own independent initiative. These victories are not the result of official policies of interculturality in healthcare, although the successes achieved tend to be ascribed to them.

Autacoid 14S,21R-dihydroxy-docosahexaenoic acid counteracts diabetic impairment of macrophage prohealing functions.

Impaired macrophage functions imposed by diabetic complications and the suppressed formation of 14S,21R-dihydroxydocosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid (14S,21R-diHDHA) in wounds contribute significantly to deficient wound healing in diabetics, but how are macrophage functions and 14S,21R-diHDHA formation associated? We studied 14S,21R-diHDHA generation from macrophages using liquid chromatography/mass spectrometry. The role in macrophage-mediated wound healing functions was determined using a murine splinted excisional wound healing model and in vitro assays. 14S,21R-diHDHA acts as a macrophage-generated autacoid, and its attenuated formation in macrophages of diabetic db/db mice was accompanied by impairment of macrophage prohealing functions. 14S,21R-diHDHA restored db/db macrophage-impaired prohealing functions by promoting wound re-epithelialization, formulation of granulation tissue, and vascularization. Additionally, 12/15-lipoxygenase-deficient macrophages, which are unable to produce 14S,21R-diHDHA, exhibited impaired prohealing functions, which also were restored by 14S,21R-diHDHA treatment. The molecular mechanism for 14S,21R-diHDHA-induced recovery of impaired prohealing functions of db/db macrophages involves enhancing their secretion of vascular endothelial growth factor and platelet-derived growth factor BB, decreasing hyperglycemia-induced generation of reactive oxygen species, and increasing IL-10 expression under inflammatory stimulation. Taken together, these results indicate that deficiency of 14S,21R-diHDHA formation by diabetic macrophages contributes to their impaired prohealing functions. Our findings provide mechanistic insights into wound healing in diabetics and suggest the possibility of using autologous macrophages/monocytes, treated with 14S,21R-diHDHA, or related compounds, to promote diabetes-impaired wound healing.

Pharmacological targets revealed by myocardial postconditioning.

Postconditioning is an intervention in which controlled, brief, intermittent periods of ischaemia at the onset of reperfusion protect myocardium from the lethal consequences of reperfusion ('reperfusion injury'). Postconditioning has been demonstrated in humans with acute myocardial infarction and offers the possibility of further limiting infarct size in patients undergoing reperfusion therapy. We review current research that focuses on the molecular mechanisms of postconditioning. The molecular pathways are incompletely mapped but they probably converge on suppression of mitochondrial permeability transition pore opening during early reperfusion, an event that is thought to promote cell death at reperfusion. A number of upstream signalling pathways, activated by autacoid factors, converge on this crucial target and these offer a range of realistic possibilities for pharmacological induction of a postconditioned state.

Maresins: novel macrophage mediators with potent antiinflammatory and proresolving actions.

The endogenous cellular and molecular mechanisms that control acute inflammation and its resolution are of wide interest. Using self-resolving inflammatory exudates and lipidomics, we have identified a new pathway involving biosynthesis of potent antiinflammatory and proresolving mediators from the essential fatty acid docosahexaenoic acid (DHA) by macrophages (MPhis). During the resolution of mouse peritonitis, exudates accumulated both 17-hydroxydocosahexaenoic acid, a known marker of 17S-D series resolvin (Rv) and protectin biosynthesis, and 14S-hydroxydocosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid from endogenous DHA. Addition of either DHA or 14S-hydroperoxydocosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid to activated MPhis converted these substrates to novel dihydroxy-containing products that possessed potent antiinflammatory and proresolving activity with a potency similar to resolvin E1, 5S,12R,18R-trihydroxyeicosa-6Z,8E,10E,14Z,16E-pentaenoic acid, and protectin D1, 10R,17S-dihydroxydocosa-4Z,7Z,11E,13E,15Z,19Z-hexaenoic acid. Stable isotope incorporation, intermediate trapping, and characterization of physical and biological properties of the products demonstrated a novel 14-lipoxygenase pathway, generating bioactive 7,14-dihydroxydocosa-4Z,8,10,12,16Z,19Z-hexaenoic acid, coined MPhi mediator in resolving inflammation (maresin), which enhances resolution. These findings suggest that maresins and this new metabolome may be involved in some of the beneficial actions of DHA and MPhis in tissue homeostasis, inflammation resolution, wound healing, and host defense.

Relative contributions of TRPA1 and TRPV1 channels in the activation of vagal bronchopulmonary C-fibres by the endogenous autacoid 4-oxononenal.

Transient receptor potential (TRP) A1 channels are cation channels found preferentially on nociceptive sensory neurones, including capsaicin-sensitive TRPV1-expressing vagal bronchopulmonary C-fibres, and are activated by electrophilic compounds such as mustard oil and cinnamaldehyde. Oxidative stress, a pathological feature of many respiratory diseases, causes the endogenous formation of a number of reactive electrophilic alkenals via lipid peroxidation. One such alkenal, 4-hydroxynonenal (4HNE), activates TRPA1 in cultured sensory neurones. However, our data demonstrate that 100 microm 4HNE was unable to evoke significant action potential discharge or tachykinin release from bronchopulmonary C-fibre terminals. Instead, another endogenously produced alkenal, 4-oxononenal (4ONE, 10 microm), which is far more electrophilic than 4HNE, caused substantial action potential discharge and tachykinin release from bronchopulmonary C-fibre terminals. The activation of mouse bronchopulmonary C-fibre terminals by 4ONE (10-100 microm) was mediated entirely by TRPA1 channels, based on the absence of responses in C-fibre terminals from TRPA1 knockout mice. Interestingly, although the robust increases in calcium caused by 4ONE (0.1-10 microm) in dissociated vagal neurones were essentially abolished in TRPA1 knockout mice, at 100 microm 4ONE caused a large TRPV1-dependent response. Furthermore, 4ONE (100 microm) was shown to activate TRPV1 channel-expressing HEK cells. In conclusion, the data support the hypothesis that 4-ONE is a relevant endogenous activator of vagal C-fibres via an interaction with TRPA1, and at less relevant concentrations, it may activate nerves via TRPV1.

Interdependence of lipoxin A4 and heme-oxygenase in counter-regulating inflammation during corneal wound healing.

In the immune-privileged cornea, epithelial wounds heal rapidly with almost no scarring and, unlike in most other tissues, acute inflammation in the absence of infection is beneficial to healing. Molecular mechanisms, which account for this striking property, remain to be clearly defined, but they likely include autacoids that control leukocyte activation. Two prominent enzymes, 12/15-lipoxygenase (LOX), which generates antiinflammatory lipid autacoids, and heme-oxygenase (HO), which generates antioxidants and carbon monoxide, are highly expressed in human and mouse corneas. LXA4, an endogenous 12/15-LOX product, proved to be a potent inhibitor of exacerbated inflammation and significantly increased re-epithelialization in corneal wounds. In vivo deletion of 12/15-LOX correlated with exacerbated inflammation and impaired wound healing in 12/15-LOX(-/-) mice, a phenotype that was rescued by treatment with LXA4. More importantly, 12/15-LOX(-/-) mice demonstrated impaired induction of HO-1 in both acute and exacerbated inflammation. Topical LXA4 restored HO-1 expression in 12/15-LOX(-/-) mice and amplified HO-1 gene expression in human corneal epithelial cells. HO-2(-/-) mice, which fail to induce HO-1, also demonstrated exacerbated inflammation in response to injury, a phenotype that, notably, correlated with a 50% reduction in endogenous LXA4 formation. Collectively, results demonstrate a critical role for LXA4 in inflammatory/reparative responses and provide the first evidence that 12/15-LOX and HO systems function in concert to control inflammation.

Micropuncture study of ion and water reabsorption regulation range in the distal tubule of triton nephron.

Micropuncture of the distal tubule in triton nephron and ultramicroanalysis of samples showed that vasotocin stimulates transport of Ca2+, Na+, Mg2+, and Cl- from the nephron lumen and increases permeability of the tubular wall for water. Prostaglandin E2 suppresses these processes.

In vitro effects of hormones and autacoids on the activity of acid phosphatase in the lysates of endotoxin-activated rat peritoneal and bronchoalveolar macrophages.

Peritoneal and bronchoalveolar macrophages activated in vitro by endotoxin, exhibit alterations in the acid phosphatase activity of cell lysates when certain hormones or autacoids are present in the culture medium. They also show morphological changes concerning general appearance and acid phosphatase cytochemistry. Certain agents known to increase the intracellular levels of cyclic AMP, such as dopamine and prostaglandin E2, decreased this enzyme activity in the lysates of peritoneal macrophages. Adrenalin had no effect on this activity at 14 hours, but was found to increase the activity in the culture medium at the initial hours of incubation. Glucagon decreased whereas insulin increased acid phosphatase activity in bronchoalveolar macrophages. Serotonin or histamine, known to activate phospholipase C, increased this activity in peritoneal or bronchoalveolar macrophages. The results of this study, taken together with previously published data (Kondomerkos et al., 2003), suggest that hormones and autacoids may control certain parameters of macrophage activation including acid phosphatase activity.

The regulation of ICAM-1 and LFA-1 interaction by autacoids and statins: a novel strategy for controlling inflammation and immune responses.

Histamine, prostaglandin E(2), and catecholamines have been demonstrated to regulate the innate and acquired immune responses. In this review, we describe one of the mechanisms common to the action of these agonists; the regulation of the expression of costimulatory adhesion molecules such as ICAM-1 and B7 antigens on monocytes/macrophages. The specific receptor subtypes involved in the action of each agonist were H(2) for histamine, EP(2)/EP(4) for prostaglandin E(2), and beta(2) for catecholamines, all of which are coupled with adenylate cyclase via Gs protein. The regulation of the expression of adhesion molecules by these agonists in turn leads to the modulation of subsequent cytokine production mediated by cell-cell interaction under different stimuli. Histamine is synthesized in monocytes and T cells by the induction of histidine decarboxylase. The inducible histamine has different dynamics from that in storage granules of mast cells and basophils. Also, noradrenaline appears to be synthesized in lymphocytes. Thus, immune cells can produce histamine, prostaglandins, and noradrenaline by themselves and modulate the cell-cell interaction between monocytes and other cells. Some of the inhibitors of HMG-CoA reductase were shown to bind to the ICAM-1-binding domain of LFA-1, reducing the interaction mediated by ICAM-1/LFA-1. The regulation of interaction mediated by adhesion molecules may provide a new target for controlling inflammatory and immune responses.

In vitro effects of hormones and autacoids on the hydrogen peroxide production and the morphology of endotoxin-activated rat peritoneal macrophages.

Peritoneal macrophages activated in vitro by endotoxin exhibit alterations of their capability to produce hydrogen peroxide after phorbol ester stimulation when certain hormones or autacoids are present in the culture medium. They also show morphological changes, mainly concerning cell size and nuclear appearance. Agents known to increase the intracellular levels of cyclic AMP, e.g. adrenalin and PGE2 reduce the hydrogen peroxide production. Insulin, which is known to decrease cyclic AMP levels, produces opposite results. Agents postulated to act via phospholipase C, e.g. serotonin, augment the production of hydrogen peroxide. We assume that this form of modulation may represent a regulatory mechanism of macrophage activation.

Tissue-specific expression of human lipoprotein lipase in the vascular system affects vascular reactivity in transgenic mice.

1. The role of smooth muscle-derived lipoprotein lipase (LPL) that translocates to the endothelium surface on vascular dysfunction during atherogenesis is unclear. Thus, the role of vascular LPL on blood vessel reactivity was assessed in transgenic mice that specifically express human LPL in the circulatory system. 2. Aortic free fatty acids (FFAs) were increased by 69% in the transgenic mice expressing human LPL in aortic smooth muscle cells (L2LPL) compared with their non-transgenic littermates (L2). 3. Contractility to KCl was increased by 33% in aortae of L2LPL mice. Maximal contraction to phenylephrine (PE) was comparable in L2 and L2LPL animals, while the frequency of tonus oscillation to PE increased by 104% in L2LPL mice. 4. In L2LPL animals, *NO mediated relaxation to acetylcholine (ACh) and ATP was reduced by 47 and 32%, respectively. In contrast, endothelium-independent relaxation to sodium nitroprusside (SNP) was not different in both groups tested. 5. ATP-initiated Ca(2+) elevation that triggers *NO formation was increased by 41% in single aortic endothelial cells freshly isolated from L2LPL animals. 6. In aortae from L2LPL mice an increased *O(2)(-) release occurred that was normalized by removing the endothelium and by the NAD(P)H oxidase inhibitor DPI and the PKC inhibitor GF109203X. 7. The reduced ACh-induced relaxation in L2LPL animals was normalized in the presence of SOD, indicating that the reduced relaxation is due, at least in part, to enhanced *NO scavenging by *O(2)(-). 8. These data suggest that despite normal lipoprotein levels increased LPL-mediated FFAs loading initiates vascular dysfunction via PKC-mediated activation of endothelial NAD(P)H oxidase. Thus, vascular LPL activity might represent a primary risk factor for atherosclerosis independently from cholesterol/LDL levels.

Overview of animal models of asthma.

Asthma is an inflammatory disease characterized by airways obstruction, airways hyperresponsiveness, excessive mucous secretion and cough. Guinea pig airways display many anatomical, physiological and pharmacological attributes of human airways, making this species ideal for modeling the asthmatic condition. This unit provides an overview of animal models of asthma, including definitions, descriptions of available animal models, and discussion of numerous critical issues to consider before designing a model to study this complex disease.

[Preoperative administration of a slow releasing somatostatin analog (SR-lanreotide, BIM 23014) in patients with acromegaly in the course of GH-releasing adenoma]. / Przedoperacyjne zastosowanie analogu somatostatyny o przedluzonym dzialaniu (SR-Lanreotide, BIM 23014) u pacjentów z akromegalia w przebiegu makrogruczolaka przysadki.

To evaluate the therapeutic efficacy of slow releasing analogue of somatostatin (SR-Lanreotide) in the pretreatment for GH-releasing adenomas, especially macroadenomas. During the last four years (between January 1996 and December 1999) the authors carried out 382 transsphenoidal operations for to various lesions. There were 169 acromegalic patients in this group. 82 of them received, as pretreatment, the slow releasing analogue of somatostatin (SR-Lanreotide, BIM 23014) in a dose of 30 mg every 14 days for 3 months (6 injections). There were 55 women and 27 men (range 25-68, mean age 44.8 years, SD +/- 10 years) operated on by one experienced neurosurgeon. The concentrations of serum GH--70.5 micrograms/l (range 5.3-500 micrograms/l, SD +/- 83.9 micrograms/l) and IGF-I--1302 micrograms/l (range 610-2030 micrograms/l, SD +/- 360.7 micrograms/l) were high. Out of these 82 patients 79 had macroadenomas with suprasellar and parasellar extension. The volume of the tumours was calculated according to the formula of Di Chiro-Nelson. The mean volume of the tumour was 4146.9 mm3 (range 213.5-38595.3 mm3, SD +/- 5675.9 mm3). The response to the pretreatment suppression of the serum GH, IGF-I level and shrinkage of the tumours--were evaluated before surgery. Second MR examination was performed in 38 pretreated patients. During the Lanreotide treatment mean serum GH level decreased from 70.5 to 15.6 micrograms/l (p < 0.0001), mean serum IGF-I concentration decreased from 1302 to 787 micrograms/l and mean volume of the tumour decreased from 5662 to 2326 mm3 (p < 0.0001). During surgery, tumours were observed to be softer, had liquid consistency and were easier removed. 57 patient (69.5%) who underwent surgery had GH below 5 micrograms/l and were cured. Transsphenoidal microsurgical resection of pituitary adenomas is the primary treatment for acromegaly. Lanreotide pretreatment significantly decreased mean serum GH and IGF-I level, shrinks the tumour and make it much softer and easier to be removed.

Endothelial adrenoceptors.

alpha2 -Adrenergic agonists cause endothelium-dependent relaxation in a number of isolated blood vessels. This effect is explained by the activation of endothelial alpha 2 -adrenoceptors linked to nitric oxide synthase by G i -coupling proteins. The endothelial response to alpha 2 -adrenergic agonists is blunted considerably after regeneration of the endothelium and in atherosclerotic arteries. The relaxation of isolated arteries caused by beta-adrenergic agonists is reduced by removal of the endothelium and, in most cases, by inhibitors of the l -arginine nitric oxide pathway. Likewise, in the intact animal and in the human forearm the vasodilatation to beta 2 -adrenergic agonists is blunted by inhibitors of nitric oxide synthase. Whether these findings reflect the presence of functional beta-adrenoceptors on the endothelium remains controversial. Several beta-adrenergic blockers cause endothelium-dependent relaxation in vitro or augment the production of nitric oxide in vivo. However, these responses cannot be attributed to interactions with endothelial beta-adrenoceptors.

Endogenous morphine and codeine. Possible role as endogenous anticonvulsants.

Exogenously administered morphine can have both convulsive or anticonvulsive effects, depending on the dose and species. The levels of the endogenous opiate alkaloids morphine and codeine were significantly elevated in specific rat brain regions by the convulsive drug, pentylenetetrazole, as well as by the anticonvulsant drugs, carbamazepine and phenytoin. Morphine and codeine levels in peripheral tissues (heart, lung, spleen and adrenal) were unaffected by these drugs. Maximal increases in morphine levels were seen in the hypothalamus and striatum (2-10-fold), while lesser increases occurred in the midbrain and brain stem (2-4-fold). Codeine levels were also markedly increased in hypothalamus (5-10 fold), In contrast to morphine, codeine levels were also increased in the hippocampus (2-10-fold), but were unchanged in the striatum. These studies suggest that the endogenous alkaloids morphine and codeine are involved in the modulation of convulsions and that morphine and/or codeine may act as an endogenous anticonvulsant.