ERP and behavioral changes during the wake/sleep transition

Event-related potentials (ERPs) following infrequent and frequent stimuli were studied as subjects moved from wakefulness to sleep. Subjects were instructed to respond to the infrequent "target" stimuli (attend condition) or to ignore the stimuli (ignore condition). Parietal P300, prominent following target ERPs in wakefulness under the attend condition, disappeared in association with reduced behavioral responsiveness and emergence of a central negativity (N350). The N350 and preceding and following positivities (P220 and P450) became the dominant feature of both target and nontarget ERPs under both attend and ignore conditions. The P220-N350-P450 complex was larger and peak latencies were shorter under the attend condition. Peak amplitudes tended to be larger following targets, especially under the attend condition. The findings suggest that, although the processes underlying P300 are less likely to be engaged, processing of stimulus deviance and task relevance continues in sleepiness and sleep, and is reflected by variance in N350 and related activity.

Stages of sleep pathology in spinocerebellar ataxia type 2 (SCA2)

BACKGROUND

Autosomal dominant spinocerebellar ataxia type 2 (SCA2) bears clinical and neuropathologic similarities to sporadic multisystem atrophy (MSA) or Parkinson disease, in which sleep pathology is well documented. However, those clinical entities have a marked variability of the reported sleep disturbances, and their etiology is heterogeneous. In contrast, the study of SCA2 provides an opportunity to examine a molecularly homogeneous patient group, in which disease stages can be defined not only based on disease duration and ataxia scores, but also with regard to modulatory effects of mutation size.

OBJECTIVE

To examine the presence and progression of sleep pathology in SCA2.

METHODS

We analyzed eight patients with disease durations of 3 to 31 years, all with medium size SCA2 expansions (CAG 38 to 49), using clinical scores, sleep interviews, and video-polysomnography (VPSG) recordings.

RESULTS

Almost all patients reported good subjective sleep quality and negated incidents of REM behavior disorder (RBD). At early disease stages, however, REM without atonia in four patients' VPSG suggested subclinical RBD. This was accompanied by a consistent reduction of REM density. In three patients at later SCA2 stages, REM sleep was undetectable, whereas slow wave sleep (SWS) was markedly increased at the cost of light sleep. Periodic leg movements, apnea, or hypopnea were not prominent.

CONCLUSIONS

Progressive loss of dream recall in spinocerebellar ataxia type 2 was found and correlated with stages of REM more than non-REM pathology in video-polysomnography. These stages correspond to the progressive atrophy from the pons, nigrostriatal projection, and locus ceruleus to the thalamus.

Enhanced beta cell function and anti-inflammatory effect after chronic treatment with the dipeptidyl peptidase-4 inhibitor vildagliptin in an advanced-aged diet-induced obesity mouse model

AIMS/HYPOTHESIS

Studies have shown that dipeptidyl peptidase-4 (DPP4) inhibitors stimulate insulin secretion and increase beta cell mass in rodents. However, in these models hyperglycaemia has been induced early on in life and the treatment periods have been short. To explore the long-term effects of DPP4 inhibition on insulin secretion and beta cell mass, we have generated a high-fat diet (HFD)-induced-obesity model in mice of advanced age (10 months old).

METHODS

After 1 month of HFD alone, the mice were given the DPP4 inhibitor vildagliptin for a further 11 months. At multiple time points throughout the study, OGTTs were performed and beta cell area and long-term survival were evaluated.

RESULTS

Beta cell function and glucose tolerance were significantly improved by vildagliptin with both diets. In contrast, in spite of the long treatment period, beta cell area was not significantly different between vildagliptin-treated mice and controls. Mice of advanced age chronically fed an HFD displayed clear and extensive pancreatic inflammation and peri-insulitis, mainly formed by CD3-positive T cells, which were completely prevented by vildagliptin treatment. Chronic vildagliptin treatment also improved survival rates for HFD-fed mice.

CONCLUSIONS/INTERPRETATION

In a unique advanced-aged HFD-induced-obesity mouse model, insulin secretion was improved and the extensive peri-insulitis prevented by chronic DPP4 inhibition. The improved survival rates for obese mice chronically treated with vildagliptin suggest that chronic DPP4 inhibition potentially results in additional quality-adjusted life-years for individuals with type 2 diabetes, which is the primary goal of any diabetes therapy.

Enteric neuropathy can be induced by high fat diet in vivo and palmitic acid exposure in vitro

Objective

Obese and/or diabetic patients have elevated levels of free fatty acids and increased susceptibility to gastrointestinal symptoms. Since the enteric nervous system is pivotal in regulating gastrointestinal functions alterations or neuropathy in the enteric neurons are suspected to occur in these conditions. Lipid induced intestinal changes, in particular on enteric neurons, were investigated in vitro and in vivo using primary cell culture and a high fat diet (HFD) mouse model.

Design

Mice were fed normal or HFD for 6 months. Intestines were analyzed for neuronal numbers, remodeling and lipid accumulation. Co-cultures of myenteric neurons, glia and muscle cells from rat small intestine, were treated with palmitic acid (PA) (0 – 10⁻³ M) and / or oleic acid (OA) (0 – 10⁻³ M), with or without modulators of intracellular lipid metabolism. Analyses were by immunocyto- and histochemistry.

Results

HFD caused substantial loss of myenteric neurons, leaving submucous neurons unaffected, and intramuscular lipid accumulation in ileum and colon. PA exposure in vitro resulted in neuronal shrinkage, chromatin condensation and a significant and concentration-dependent decrease in neuronal survival; OA exposure was neuroprotective. Carnitine palmitoyltransferase 1 inhibition, L-carnitine- or alpha lipoic acid supplementation all counteracted PA-induced neuronal loss. PA or OA alone both caused a significant and concentration-dependent loss of muscle cells in vitro. Simultaneous exposure of PA and OA promoted survival of muscle cells and increased intramuscular lipid droplet accumulation. PA exposure transformed glia from a stellate to a rounded phenotype but had no effect on their survival.

Conclusions

HFD and PA exposure are detrimental to myenteric neurons. Present results indicate excessive palmitoylcarnitine formation and exhausted L-carnitine stores leading to energy depletion, attenuated acetylcholine synthesis and oxidative stress to be main mechanisms behind PA-induced neuronal loss.High PA exposure is suggested to be a factor in causing diabetic neuropathy and gastrointestinal dysregulation.

Distribution of melatonin receptors in murine pancreatic islets

Melatonin has multiple receptor-dependent and receptor-independent functions. At the cell membrane, melatonin interacts with its receptors MT1 and MT2, which are expressed in numerous tissues. Genome-wide association studies have recently shown that the MTNR1B/MT2 receptor may be involved in the pathogenesis of type 2 diabetes mellitus. In line with these findings, expression of melatonin receptors has been shown in mouse, rat, and human pancreatic islets. MT1 and MT2 are G-protein-coupled receptors and are proposed to exert inhibitory effects on insulin secretion. Here, we show by immunocytochemistry that these membrane melatonin receptors have distinct locations in the mouse islet. MT1 is expressed in α-cells while MT2 is located to the β-cells. These findings help to unravel the complex machinery underlying melatonin's role in the regulation of islet function.

N-cadherin is dispensable for pancreas development but required for beta-cell granule turnover

The cadherin family of cell adhesion molecules mediates adhesive interactions that are required for the formation and maintenance of tissues. Previously, we demonstrated that N-cadherin, which is required for numerous morphogenetic processes, is expressed in the pancreatic epithelium at E9.5, but later becomes restricted to endocrine aggregates in mice. To study the role of N-cadherin during pancreas formation and function we generated a tissue-specific knockout of N-cadherin in the early pancreatic epithelium by inter-crossing N-cadherin-floxed mice with Pdx1Cre mice. Analysis of pancreas-specific ablation of N-cadherin demonstrates that N-cadherin is dispensable for pancreatic development, but required for beta-cell granule turnover. The number of insulin secretory granules is significantly reduced in N-cadherin-deficient beta-cells, and as a consequence insulin secretion is decreased.

Tuft cells: Distribution and connections with nerves and endocrine cells in mouse intestine

Tuft cells are gastrointestinal (GI) sensory cells recognized by their characteristic shape and their microvilli "tuft". Aims of the present study were to elucidate their regional distribution and spatial connections with satiety associated endocrine cells and nerve fibers throughout the intestinal tract. C57BL/6 J mice were used in the experiments. The small intestine was divided into five segments, and the large intestine was kept undivided. The segments were coiled into "Swiss rolls". Numbers and topographic distribution of tuft cells and possible contacts with endocrine cells and nerve fibers were estimated in the different segments, using immunocytochemistry. Tuft cells were found throughout the intestines; the highest number was in proximal small intestine. Five percent of tuft cells were found in close proximity to cholecystokinin-immunoreactive (IR) endocrine cells and up to 10% were in contact with peptide YY- and glucagon-like peptide-1-IR endocrine cells. Sixty percent of tuft cells in the small intestine and 40% in the large intestine were found in contact with nerve fibers. Calcitonin gene-related peptide-IR fibers constituted one-third of the fiber-contacts in the small intestine and two-thirds in the large intestine. These observations highlight the possibility of tuft cells as modulators of GI activities in response to luminal signaling.

Enhanced colonic tumorigenesis in alkaline sphingomyelinase (NPP7) knockout mice

Intestinal alkaline sphingomyelinase (alk-SMase) generates ceramide and inactivates platelet-activating factor (PAF) and was previously suggested to have anticancer properties. The direct evidence is still lacking. We studied colonic tumorigenesis in alk-SMase knockout (KO) mice. Formation of aberrant crypt foci (ACF) was examined after azoxymethane (AOM) injection. Tumor was induced by AOM alone, a conventional AOM/dextran sulfate sodium (DSS) treatment, and an enhanced AOM/DSS method. β-Catenin was determined by immunohistochemistry, PAF levels by ELISA, and sphingomyelin metabolites by mass spectrometry. Without treatment, spontaneous tumorigenesis was not identified but the intestinal mucosa appeared thicker in KO than in wild-type (WT) littermates. AOM alone induced more ACF in KO mice but no tumors 28 weeks after injection. However, combination of AOM/DSS treatments induced colonic tumors and the incidence was significantly higher in KO than in WT mice. By the enhanced AOM/DSS method, tumor number per mouse increased 4.5 times and tumor size 1.8 times in KO compared with WT mice. Although all tumors were adenomas in WT mice, 32% were adenocarcinomas in KO mice. Compared with WT mice, cytosol expression of β-catenin was significantly increased and nuclear translocation in tumors was more pronounced in KO mice. Lipid analysis showed decreased ceramide in small intestine and increased sphingosine-1-phosphate (S1P) in both small intestine and colon in nontreated KO mice. PAF levels in feces were significantly higher in the KO mice after AOM/DSS treatment. In conclusion, lack of alk-SMase markedly increases AOM/DSS-induced colonic tumorigenesis associated with decreased ceramide and increased S1P and PAF levels.

High glucose and free fatty acids induce beta cell apoptosis via autocrine effects of ADP acting on the P2Y(13) receptor

While high levels of glucose and saturated fatty acids are known to have detrimental effects on beta cell function and survival, the signalling pathways mediating these effects are not entirely known. In a previous study, we found that ADP regulates beta cell insulin secretion and beta cell apoptosis. Using MIN6c4 cells as a model system, we investigated if autocrine/paracrine mechanisms of ADP and purinergic receptors are involved in this process. High glucose (16.7 mmol/l) and palmitate (100 μmol/l) rapidly and potently elevated the extracellular ATP levels, while mannitol was without effect. Both tolbutamide and diazoxide were without effect, while the calcium channel blocker nifedipine, the volume-regulated anion channels (VRAC) inhibitor NPPB, and the pannexin inhibitor carbenoxolone could inhibit both effects. Similarly, silencing the MDR1 gene also blocked nutrient-generated ATP release. These results indicate that calcium channels and VRAC might be involved in the ATP release mechanism. Furthermore, high glucose and palmitate inhibited cAMP production, reduced cell proliferation in MIN6c4 and increased activated Caspase-3 cells in mouse islets and in MIN6c4 cells. The P2Y(13)-specific antagonist MRS2211 antagonized all these effects. Further studies showed that blocking the P2Y(13) receptor resulted in enhanced CREB, Bad and IRS-1 phosphorylation, which are known to be involved in beta cell survival and insulin secretion. These findings provide further support for the concept that P2Y(13) plays an important role in beta cell apoptosis and suggest that autocrine/paracrine mechanisms, related to ADP and P2Y(13) receptors, contribute to glucolipotoxicity.

Gonadotropin-releasing hormone analog buserelin causes neuronal loss in rat gastrointestinal tract

Gonadotropin-releasing hormone (GnRH) analogs are given to women undergoing in vitro fertilization. Case reports describing the development of chronic intestinal pseudo-obstruction and auto-antibodies against GnRH after such treatment suggest a strong association between intestinal dysfunction and GnRH analogs. No experimental model for studying such a relationship is currently at hand. Our main goal was to investigate possible enteric neurodegeneration and titers of GnRH antibodies in response to repeated administration of the GnRH analog buserelin in rat. Rats were treated for 1-4 sessions with daily subcutaneous injections of buserelin or saline for 5 days, followed by 3 weeks of recovery. Buserelin treatment caused significant loss of submucous and myenteric neurons in the fundus, ileum, and colon. The loss of enteric neurons can, at least partly, be explained by increased apoptosis. No GnRH- or GnRH-receptor-immunoreactive (IR) enteric neurons but numerous luteinizing hormone (LH)-receptor-IR neurons were detected. After buserelin treatment, the relative number of enteric LH-receptor-IR neurons decreased, whereas that of nitric-oxide-synthase-IR neurons increased. No intestinal inflammation or increased levels of circulating interleukins/cytokines were noted in response to buserelin treatment. Serum GnRH antibody titers were undetectable or extremely low in all rats. Thus, repeated administrations of buserelin induce neurodegeneration in rat gastrointestinal tract, possibly by way of LH-receptor hyperactivation. The present findings suggest that enteric neurodegenerative effects of GnRH analog treatment in man can be mimicked in rat. However, in contrast to man, no production of GnRH auto-antibodies has been noted in rat.

Information processing and coping style during the wake/sleep transition

Information processing of meaningful events (subject's own name, neutral name and tones) was studied during the transition from wakefulness to sleep in two groups of subjects with opposing information processing styles, Monitors and Blunters. In two experimental sets, subjects were instructed to execute a fingerlift response to a predetermined stimulus type. Subject's own name produced the greatest number of K-complexes and arousals relative to other name and tones. A task relevance effect was found for arousals but not for K-complexes. The overall P3 amplitude was larger for Monitors than for Blunters, whereas Blunters showed a larger N350 to target stimuli than Monitors. The findings suggest that higher level processing continues during light sleep and that N350 may reflect a process related to sleep maintenance.

Glucagon-like peptides 1 and 2 and vasoactive intestinal peptide are neuroprotective on cultured and mast cell co-cultured rat myenteric neurons

BACKGROUND

Neuropathy is believed to be a common feature of functional and inflammatory intestinal diseases. Vasoactive intestinal peptide (VIP) is an acknowledged neuroprotective agent in peripheral, including enteric, and central neurons. The proglucagon-like hormones glucagon-like peptide 1 and 2 (GLP1 and GLP2) belong to the secretin/glucagon/VIP superfamily of peptides and GLP1 and GLP2 receptors are expressed in enteric neurons. Possible neuroprotective effects of these peptides were investigated in the present study.

METHODS

GLP1, GLP2 and VIP were added to cultured myenteric neurons from rat small intestine or to co-cultures of myenteric neurons and rat peritoneal mast cells. Receptor selectivity was tested by the simultaneous presence of a GLP1 receptor antagonist (exendin (9-39) amide) or a VIP receptor antagonist (hybrid of neurotensin 6-11 and VIP 7-28). Neuronal survival was examined using immunocytochemistry and cell counting.

RESULTS

GLP1, GLP2 and VIP significantly and concentration-dependently enhanced neuronal survival. In addition the peptides efficiently counteracted mast cell-induced neuronal cell death in a concentration-dependent manner. Exendin(9-39)amide reversed GLP1-induced neuroprotection while GLP2- and VIP-induced enhanced neuronal survival were unaffected. The VIP receptor antagonist reversed GLP1- and VIP-induced neuroprotection while the GLP2-induced effect on neuronal survival was unaffected.

CONCLUSIONS

By activating separate receptors VIP, GLP1 and GLP2 elicit neuroprotective effects on rat myenteric neurons cultured with or without mast cells. This implies a powerful therapeutic potential of these peptides in enteric neuropathies with a broad spectrum of applications from autoimmunity to functional disorders.

The enteric nervous system of P2Y13 receptor null mice is resistant against high-fat-diet- and palmitic-acid-induced neuronal loss

Gastrointestinal symptoms have a major impact on the quality of life and are becoming more prevalent in the western population. The enteric nervous system (ENS) is pivotal in regulating gastrointestinal functions. Purinergic neurotransmission conveys a range of short and long-term cellular effects. This study investigated the role of the ADP-sensitive P2Y13 receptor in lipid-induced enteric neuropathy. Littermate P2Y13 (+/+) and P2Y13 (-/-) mice were fed with either a normal diet (ND) or high-fat diet (HFD) for 6 months. The intestines were analysed for morphological changes as well as neuronal numbers and relative numbers of vasoactive intestinal peptide (VIP)- and neuronal nitric oxide synthase (nNOS)-containing neurons. Primary cultures of myenteric neurons from the small intestine of P2Y13 (+/+) or P2Y13 (-/-) mice were exposed to palmitic acid (PA), the P2Y13 receptor agonist 2meSADP and the antagonist MRS2211. Neuronal survival and relative number of VIP-containing neurons were analysed. In P2Y13 (+/+), but not in P2Y13 (-/-) mice, HFD caused a significant loss of myenteric neurons in both ileum and colon. In colon, the relative numbers of VIP-containing submucous neurons were significantly lower in the P2Y13 (-/-) mice compared with P2Y13 (+/+) mice. The relative numbers of nNOS-containing submucous colonic neurons increased in P2Y13 (+/+) HFD mice. HFD also caused ileal mucosal thinning in P2Y13 (+/+) and P2Y13 (-/-) mice, compared to ND fed mice. In vitro PA exposure caused loss of myenteric neurons from P2Y13 (+/+) mice while neurons from P2Y13 (-/-) mice were unaffected. Presence of MRS2211 prevented PA-induced neuronal loss in cultures from P2Y13 (+/+) mice. 2meSADP caused no change in survival of cultured neurons. P2Y13 receptor activation is of crucial importance in mediating the HFD- and PA-induced myenteric neuronal loss in mice. In addition, the results indicate a constitutive activation of enteric neuronal apoptosis by way of P2Y13 receptor stimulation.

Sleep quality in a family with hereditary parkinsonism (PARK6)

OBJECTIVES

The autosomal recessive disorder PARK6 manifests as early-onset Parkinson's disease (PD) with a particularly mild progression. PARK6 is of particular scientific interest, since it is caused by loss-of-function mutations in the mitochondrial protein kinase PINK1 and may thus serve as a model for oxidative damage in PD and in other basal ganglia disorders. Sleep disturbances are very common in PD but have not yet been reported for PARK6 patients. The present study reports on sleep of a Spanish family with PARK6. Of the 5 siblings, 3 were homozygous and severely affected, and 2 were heterozygous and clinically asymptomatic. Research questions concerned possible differences in sleep recordings between homozygote and heterozygote siblings and similarities between PARK6 and sporadic PD sleep profiles.

METHOD

The data from detailed clinical interviews of the patients and their bedpartners are reported and compared with polysomnographic data from second-night recordings.

CONCLUSIONS

All siblings had good subjective and objective sleep quality. Restless legs syndrome and rapid eye movement (REM) sleep behaviour disorder (RBD) were not observed, suggesting that sleep disturbances are not commonly found in PARK6 patients. Good sleep quality and the absence of RBD might be a useful diagnostic guide in the differential diagnosis of sporadic PD versus PARK6.

Lingonberries and their two separated fractions differently alter the gut microbiota, improve metabolic functions, reduce gut inflammatory properties, and improve brain function in ApoE-/- mice fed high-fat diet

Lingonberries (LB) have been shown to have beneficial metabolic effects, which is associated with an altered gut microbiota. This study investigated whether the LB-induced improvements were associated with altered gut- and neuroinflammatory markers, as well as cognitive performance in ApoE-/- mice fed high-fat (HF) diets. Whole LB, as well as two separated fractions of LB were investigated. Eight-week-old male ApoE-/- mice were fed HF diets (38% kcal) containing whole LB (wLB), or the insoluble (insLB) and soluble fractions (solLB) of LB for 8 weeks. Inclusion of wLB and insLB fraction reduced weight gain, reduced fat deposition and improved glucose response. Both wLB and insLB fraction also changed the caecal microbiota composition and reduced intestinal S100B protein levels. The solLB fraction mainly induced weight loss in the mice. There were no significant changes in spatial memory, but significant increases in synaptic density in the hippocampus were observed in the brain of mice-fed wLB and insLB. Thus, this study shows that all lingonberry fractions counteracted negative effects of HF feedings on metabolic parameters. Also, wLB and insLB fraction showed to potentially improve brain function in the mice.

Neuroprotective effects of vitamin D on high fat diet- and palmitic acid-induced enteric neuronal loss in mice

Background

The role of vitamin D in obesity and diabetes is debated. Obese and/or diabetic patients have elevated levels of free fatty acids, increased susceptibility to gastrointestinal symptoms and are suggested to have altered vitamin D balance. The enteric nervous system is pivotal in regulating gastrointestinal activity and high fat diet (HFD) has been shown to cause loss of enteric neurons in ileum and colon. This study investigates the effect of vitamin D on HFD- and palmitic acid-induced enteric neuronal loss in vivo and in vitro.

Methods

Mice were fed either a normal diet (ND) or HFD supplemented with varying levels of vitamin D (from 0x to 20x normal vitamin D level) for 19 weeks. Ileum and colon were analyzed for neuronal numbers and remodeling. Primary cultures of myenteric neurons from mouse small intestine were treated with palmitic acid (4x10^-4M) and/or 1α,25-hydroxy-vitamin D3 (VD, 10^-11- 10^-7M) with or without modulators of lipid metabolism and VD pathways. Cultures were analyzed by immunocyto- and histochemical methods.

Results

Vitamin D supplementation had no effect on enteric neuronal survival in the ND group. HFD caused substantial loss of myenteric neurons in ileum and colon. Vitamin D supplementation between 0-2x normal had no effect on HFD-induced neuronal loss. Supplementation with 20x normal, prevented the HFD-induced neuronal loss. In vitro supplementation of VD prevented the palmitic acid-induced neuronal loss. The VD receptor (VDR) was not identified in enteric neurons. Enteric glia expressed the alternative VD receptor, protein disulphide isomerase family A member 3 (PDIA3), but PDIA3 was not found to mediate the VD response in vitro. Inhibition of peroxisome proliferator-activated receptor gamma (PPARγ) and immune neutralization of isocitrate lyase prevented the VD mediated neuroprotection to palmitic acid exposure.

Conclusions

Results show that VD protect enteric neurons against HFD and palmitic acid induced neuronal loss. The mechanism behind is suggested to be through activation of PPARγ leading to improved neuronal peroxisome function and metabolism of neuronal lipid intermediates.

Vitamin D-induced up-regulation of human keratinocyte cathelicidin anti-microbial peptide expression involves retinoid X receptor α

The biologically active form of vitamin D, 1α,25-dihydroxyvitamin D3 (1,25D3), has been reported to positively regulate the human cathelicidin anti-microbial peptide (CAMP) gene coding for LL-37, but the mechanisms are not completely understood. We have determined the expression of CAMP, vitamin D receptor (VDR), and the retinoid X receptor (RXR) isoforms in human skin and gingival tissue biopsies and investigated the signaling pathways involved in 1,25D3-induced upregulation of CAMP. Human skin and gingival biopsies exhibited few VDR-immunoreactive cells within the stratum basale, whereas rat colon enterocytes (positive control) possessed abundant VDR immunoreactivity. Nuclear VDR immunoreactivity was demonstrated in human skin keratinocytes (HaCaT cells). Gene analysis revealed that human skin biopsies expressed higher levels of both CAMP and RXRα mRNA than human gingival biopsies, whereas VDR and RXRβ transcript levels were similar in skin and gingiva. In HaCaT cells, treatment with 1,25D3 (5 nM and 1 μM) for 4 and 24 h up-regulated CAMP mRNA several fold, and treatment with 1,25D3 for 24 h increased protein expression of the pro-form of LL-37 (hCAP-18) by about 13 times. The 1,25D3-evoked stimulation of HaCaT CAMP expression was associated with attenuated VDR mRNA and protein expression. Treatment with RXRα short interfering RNA reversed the 1,25D3-induced CAMP expression in HaCaT cells, showing that RXRα is involved in the up-regulation of CAMP by 1,25D3. We conclude that the 1,25D3-evoked stimulation of CAMP expression in human skin keratinocytes is dependent on RXRα but is not associated with the up-regulation of VDR expression.

The host defense peptide LL-37 is detected in human parotid and submandibular/sublingual saliva and expressed in glandular neutrophils

The human host defense peptide, LL-37, is an important player in the first line of defense against invading microorganisms. LL-37 and its precursor, hCAP18, have been detected in unstimulated whole saliva but no reports showing hCAP18/LL-37 in isolated, parotid, and/or submandibular/sublingual saliva have been presented. Here, we measured the levels of hCAP18/LL-37 in human parotid and submandibular/sublingual saliva and investigated the expression of hCAP18/LL-37 in parotid and submandibular gland tissue. Parotid and submandibular/sublingual saliva was collected from healthy volunteers, and the levels of hCAP18/LL-37 in saliva were analyzed by dot blot, ELISA, and western blotting. Cellular expression of hCAP18/LL-37 in human parotid and submandibular glands was investigated by immunohistochemistry. Immunoreactivity for hCAP18/LL-37 was detected in both parotid and submandibular/sublingual saliva of all individuals. The concentration of hCAP18/LL-37 was similar in parotid and submandibular/sublingual saliva, and was determined by densitometric scanning of each dot and normalization to the total protein concentration of each sample, and by ELISA. Double immunohistochemistry revealed that intravascular neutrophils of both parotid and submandibular glands express hCAP18/LL-37. For the first time, we demonstrate hCAP18/LL-37 in isolated human parotid and submandibular/sublingual saliva and expression of hCAP18/LL-37 in glandular intravascular neutrophils, indicating that neutrophils of the major salivary glands contribute to the LL-37 content of whole saliva.

Luteinizing hormone receptors are expressed in rat myenteric neurons and mediate neuronal loss

BACKGROUND

Clinical observations have suggested repeated gonadotropin-releasing hormone (GnRH) exposure to cause intestinal dysfunction and loss of enteric neurons. This has been further studied and confirmed in a rat in vivo model involving iterated GnRH treatments. Mechanisms behind are enigmatic since no GnRH receptors are found to be expressed in enteric neurons neither in man nor rat. Both species, however, harbor substantial subpopulations of luteinizing hormone (LH) receptor-immunoreactive myenteric neurons which suggests that intestinal GnRH-induced neuropathy may be mediated by LH release.

AIMS

To reveal if exposures of GnRH or LH to rat myenteric neurons in vitro cause neuronal loss.

METHODS

Primary cultured adult rat myenteric neurons were exposed to single or repeated treatments of the GnRH analog buserelin or the LH analog lutrotropin alpha, and neuronal survival was determined by cell counting. Possible presence of GnRH- or LH receptor -immunoreactive neurons was determined by immunocytochemistry.

RESULTS

Exposure to the LH, but not the GnRH, analog caused significantly reduced neuronal survival. LH, but not GnRH, receptors were found to be expressed on cultured myenteric neurons.

CONCLUSION

Myenteric neurons express LH receptors in vitro and LH exposure causes reduced neuronal survival. This suggests that GnRH-induced enteric neuropathy in vivo is mediated by way of LH release and activation of enteric neuronal LH receptors.

Effects of neonatal sympathectomy by 6-hydroxydopamine on blood pressure and intravascular volume in young stroke-prone spontaneously hypertensive rats

1. Stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY) were 'chemically sympathectomized' immediately after birth with 6-hydroxydopamine (6-OHDA, 100 mg/kg s.c. daily) for the first 10 days of life. 2. Body weight gain was diminished in both groups as compared with sham-treated controls. Blood pressure was reduced in 'sympathectomized' SHRSP, and also WKY rats had a slightly lower blood pressure than control rats. 3. Plasma concentration of angiotensin II and renin content of the kidney were not influenced by 6-OHDA. 4. 'Sympathectomized' SHRSP retained similar amounts of sodium than sham-treated SHRSP when sodium retention is expressed per body weight gained. Plasma and blood volumes were increased in both SHRSP and WKY rats, whereas packed cell volume was significantly decreased. 5. These results demonstrate the significance of an intact sympathetic nervous system for the development of hypertension in SHRSP. The expanded plasma and blood volume in 'sympathectomized' rats indicate an important role of the sympathetic nervous system and/or the arterial blood pressure for the regulation of intravascular volume.

Effect of neonatal sympathectomy by 6-hydroxydopamine on volume and resistance regulation in stroke-prone spontaneously hypertensive rats

1. Neonatal sympathectomy with 6 hydroxy-dopamine (6-OHDA) was used as a tool to assess the significance of an increased sympathetic vascular tone for the development of high blood pressure in stroke-prone spontaneously hypertensive rats. After administration of 6-OHDA the rise in blood pressure was blunted for the following 9 weeks until innervation was re-established. 6-OHDA-treated rats retained more sodium and had larger plasma and blood volumes than sham-treated rats. 2. Catecholamines in plasma were increased 2-10-fold immediately after sympathectomy, but their concentrations were subnormal on day 7. Eight weeks after sympathectomy plasma noradrenaline and dopamine were not elevated, but plasma adrenaline has increased twofold. 3. The reactivity of resistance vessels to noradrenaline was markedly enhanced and the neuronal uptake and metabolism of noradrenaline were still reduced 8 weeks after neonatal sympathectomy. 4. These results confirm the significance of an intact sympathetic nervous system for the development in these rats. Sodium retention and increased plasma and blood volume may be considered as a compensatory mechanism for the vasodilatation resulting from decreased vasomotor tone.