alpha-Melanocyte-stimulating hormone is neuroprotective in rat global cerebral ischemia

Distribution and cellular localization of adrenoleukodystrophy protein in human tissues: implications for X-linked adrenoleukodystrophy

Defects of adrenoleukodystrophy protein (ALDP) lead to X-linked adrenoleukodystrophy (X-ALD), a disorder mainly affecting the nervous system white matter and the adrenal cortex. In the present study, we examine the expression of ALDP in various human tissues and cell lines by multiple-tissue RNA expression array analysis, Western blot analysis, and immunohistochemistry. ALDP-encoding mRNA is most abundant in tissues with high energy requirements such as heart, muscle, liver, and the renal and endocrine systems. ALDP selectively occurs in specific cell types of brain (hypothalamus and basal nucleus of Meynert), kidney (distal tubules), skin (eccrine gland, hair follicles, and fibroblasts), colon (ganglion cells and epithelium), adrenal gland (zona reticularis and fasciculata), and testis (Sertoli and Leydig cells). In pituitary gland, ALDP is confined to adrenocorticotropin-producing cells and is significantly reduced in individuals receiving long term cortisol treatment. This might indicate a functional link between ALDP and proopiomelanocortin-derived peptide hormones.

Inflammation in the nervous system--physiological and pathophysiological aspects

There is ample evidence for the occurrence of inflammatory processes in most major neurodegenerative disorders, both in acute conditions such as traumatic brain injury and stroke, and in chronic disorders such as Alzheimer's disease, epilepsy, amyotrophic lateral sclerosis and Parkinson's disease. Studies on inflammatory factors such as pro- and antiinflammatory cytokines in experimental models of neurodegenerative disorders suggest that they are not merely bystanders, but may be involved in the neurodegenerative process. In addition, there are findings indicating that inflammatory factors may have beneficial effects on the nervous system, particularly during development of the nervous system. The challenge is to understand when, where and during which circumstances inflammation and inflammatory factors are positive or negative for neuronal survival and functioning. Some of our studies on cytokines, particularly the interleukin-1 system, are summarised and discussed in relation to neurodegeneration, cognition, and temperature changes.

Comparison of single- and repeated-ischemia-induced changes in expression of flip and flop splice variants of AMPA receptor subtypes GluR1 and GluR2 in the rats hippocampus CA1 subregion

In addition to their role in physiological activities, ionotropic glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) play an important role in neuronal death, especially that following ischemic insults. In this study, we examined the effect of single (SI) and twice repeated (RI)-4-vessel occlusion-ischemia on rat performance in the 8-armed radial maze test. Moreover, the effects of SI and RI on the AMPARs subunits glutamate receptor (GluR) 1 and GluR2 flip and flop variants composition in the CA1 subregion of the hippocampus were investigated using RT-PCR, normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and expressed as their ratios to the latter. The results showed that SI and RI impaired the maze performance by decreasing correct choices and increasing the error choices, but RI increased error choices to a greater extent than the SI. The SI reduced only GluR1 flip/GAPDH on day 1. The SI did not alter ratios of GluR2 variants to those of GluR1. On the other hand, the RI decreased GluR2 flip and flop variants after 1 and 3 days, respectively, whereas after 7 days, it increased the flip variant of both GluR1 and GluR2. Moreover, the RI reduced ratios of GluR2 variants to those of GluR1. These results reveal the differential effects of the SI and RI on memory and expression of the AMPARs subunits GluR1 and GluR2 and their flip and flop variants in the CA1.

Estimation of the hypothermic component in neuroprotection provided by cannabinoids following cerebral ischemia

Cannabinoids have neuroprotective potentials, and the expression of endocannabinoids as well as cannabinoid receptors is induced after cerebral ischemia. They also induce hypothermia by lowering the hypothalamic set point. We have estimated the significance of such hypothermia in ischemic neuroprotection following systemic administration of WIN 55,212-2, a synthetic cannabinoid receptor agonist. Results showed that WIN 55,212-2 significantly reduced infarct volumes of rats subjected to focal cerebral ischemia (middle cerebral artery occlusion) and significantly decreased ischemic CA1 damage in rats subjected to global cerebral ischemia (two-vessel occlusion). A significant (approximately 50%) part of this neuroprotection was provided by WIN 55,212-2 induced hypothermia (33.7+/-1.1 degrees C/34.9+/-1.6 degrees C), because prevention of hypothermia by maintaining body core temperatures between 37.0 and 38.0 degrees C dissolved the neuroprotective effect into a hypothermic component and an unidentified component. Finally, the ability of WIN 55,212-2 to reduce levels of the proinflammatory cytokine IFNgamma in the infarcted hemisphere of rats subjected to focal cerebral ischemia required hypothermia. For the cannabinoid WIN 55,212-2, we have isolated and directly demonstrated that hypothermia is only part of, although significant, cannabinoid mediated neuroprotection in both global and focal cerebral ischemia. We conclude that cannabinoids are reliable candidates for drug-induced hypothermia and neuroprotection. These neuroprotective effects of cannabinoids could provide the basis for potential therapeutic uses of cannabinoids and/or endocannabinoids in stroke.

Effects of the COOH-terminal tripeptide alpha-MSH(11-13) on corneal epithelial wound healing: role of nitric oxide

It is known that alpha-melanocyte stimulating hormone (alpha-MSH) may exert anti-inflammatory effects and facilitate reparative processes in different tissues. The effective message sequence of alpha-MSH resides in the COOH-terminal tripeptide alpha-MSH(11-13). This study was undertaken to investigate the effects of topical administration of the COOH-terminal tripeptide sequence of alpha-MSH (alpha-MSH(11-13), KPV) on corneal epithelial wound healing in rabbits and the possible role of nitric oxide (NO) in these effects. The whole corneal epithelium was denuded in both eyes by mechanical abrasion. The area of the corneal epithelial defect was stained with fluorescein, photographed, and then measured before the treatment and every 12 h by a computerized software. The mean epithelial wound area and the mean percent of epithelial defect remaining at each follow-up control were compared between experimental groups. Rabbits were topically treated with KPV 1, 5 or 10 mg/ml (30 microl), two drops four times in a day, for 4 days, starting immediately after corneal abrasion, while control animals received topical phosphate-buffered saline as vehicle. In order to study the role of NO in corneal repair processes, the NO donor, sodium nitroprusside (SP, 10 mg/ml, 30 microl) was administered in both eyes, two drops four times in a day, for 4 days. The effects of KPV or SP were challenged by pre-treatment with the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 10 mg/ml, 30 microl) 30 min prior to KPV or SP instillation. The mean percent epithelial defect remaining each time was significantly smaller in animals treated with KPV or SP in comparison to controls. Sixty hours later, eight out of eight (100%) corneas treated with KPV or SP were completely re-epithelized (P<0.05) while none of the corneas treated with placebo were re-epithelized. Pre-treatment with L-NAME inhibited the facilitating effect of KPV on corneal epithelial wound healing process and totally prevented the effect of SP. Rabbit corneal epithelial cells (RCE) in culture were exposed for 1, 6 and 24 h to different KPV concentrations (0.1, 1 and 10 microM) in medium containing 15% foetal bovine serum (FBS). Cell viability was stimulated by 1 and 10 microM concentrations of the substance. Thus, KPV may facilitate corneal epithelial wound healing in rabbits with a mechanism that may involve NO disposition in corneal tissue. However, it is not known whether this mechanism is likely to depend on a direct stimulating repairing activity shared by the entire molecule of alpha-MSH.