Diverging trends for onset of acute myocardial infarction, heart failure, stroke and mortality in young males: role of changes in obesity and fitness.

BACKGROUND: As opposed to the decreasing overall rates of coronary heart disease (CHD) incidence and overall cardiovascular disease (CVD) mortality, heart failure (HF) and stroke incidence are increasing in young people, potentially due to rising rates of obesity and reduced cardiorespiratory fitness (CRF). OBJECTIVES: We investigated trends in early major CVD outcomes in a large cohort of young men. METHODS: Successive cohorts of Swedish military conscripts from 1971 to 1995 (N = 1,258,432; mean age, 18.3 years) were followed, using data from the National Inpatient and Cause of Death registries. Cox proportional hazard models were used to analyse changes in 21-year CVD event rates. RESULTS: 21-year CVD and all-cause mortality and incidence of acute myocardial infarction (AMI) decreased progressively. Compared with the cohort conscripted in 1971-1975 (reference), the hazard ratios (HRs) for the last 1991-1995 cohort were 0.50 [95% confidence interval (CI) 0.42-0.59] for CVD mortality; 0.57 (95% CI 0.54-0.60) for all-cause mortality; and 0.63 (95% CI 0.53-0.75) for AMI. In contrast, the incidence of ischaemic stroke, intracerebral haemorrhage and HF increased with HRs of 1.43 (95% CI 1.17-1.75), 1.30 (95% CI 1.01-1.68) and 1.84 (95% CI 1.47-2.30), respectively. During the period, rates of obesity increased from 1.04% to 2.61%, whilst CRF scores decreased slightly. Adjustment for these factors influenced these secular trends only moderately. CONCLUSION: Secular trends of young-onset CVD events demonstrated a marked shift from AMI and CVD mortality to HF and stroke incidence. Trends were significantly, though moderately, influenced by changing baseline BMI and CRF.

Cardiovascular fitness in late adolescent males and later risk of serious non-affective mental disorders: a prospective, population-based study.

BACKGROUND: Cardiovascular fitness in late adolescence is associated with future risk of depression. Relationships with other mental disorders need elucidation. This study investigated whether fitness in late adolescence is associated with future risk of serious non-affective mental disorders. Further, we examined how having an affected brother might impact the relationship. METHOD: Prospective, population-based cohort study of 1 109 786 Swedish male conscripts with no history of mental illness, who underwent conscription examinations at age 18 between 1968 and 2005. Cardiovascular fitness was objectively measured at conscription using a bicycle ergometer test. During the follow-up (3-42 years), incident cases of serious non-affective mental disorders (schizophrenia and schizophrenia-like disorders, other psychotic disorders and neurotic, stress-related and somatoform disorders) were identified through the Swedish National Hospital Discharge Register. Cox proportional hazards models were used to assess the influence of cardiovascular fitness at conscription and risk of serious non-affective mental disorders later in life. RESULTS: Low fitness was associated with increased risk for schizophrenia and schizophrenia-like disorders [hazard ratio (HR) 1.44, 95% confidence interval (CI) 1.29-1.61], other psychotic disorders (HR 1.41, 95% CI 1.27-1.56), and neurotic or stress-related and somatoform disorders (HR 1.45, 95% CI 1.37-1.54). Relationships persisted in models that included illness in brothers. CONCLUSIONS: Lower fitness in late adolescent males is associated with increased risk of serious non-affective mental disorders in adulthood.

Peripheral infusion of IGF-I selectively induces neurogenesis in the adult rat hippocampus.

In several species, including humans, the dentate granule cell layer (GCL) of the hippocampus exhibits neurogenesis throughout adult life. The ability to regulate adult neurogenesis pharmacologically may be of therapeutic value as a mechanism for replacing lost neurons. Insulin-like growth factor-I (IGF-I) is a growth-promoting peptide hormone that has been shown to have neurotrophic properties. The relationship between IGF-I and adult hippocampal neurogenesis is to date unknown. The aim of this study was to investigate the effect of the peripheral administration of IGF-I on cellular proliferation in the dentate subgranular proliferative zone, which contains neuronal progenitor cells, and on the subsequent migration and differentiation of progenitor cells within the GCL. Using bromodeoxyuridine (BrdU) labeling, we found a significant increase of BrdU-immunoreactive progenitors in the GCL after 6 d of peripheral IGF-I administration. To determine the cell fate in progenitor progeny, we characterized the colocalization of BrdU-immunolabeled cells with cell-specific markers. In animals treated with IGF-I for 20 d, BrdU-positive cells increased significantly. Furthermore, the fraction of newly generated neurons in the GCL increased, as evaluated by the neuronal markers Calbindin D(28K), microtubule-associated protein-2, and NeuN. There was no difference in the fraction of newly generated astrocytes. Thus, our results show that peripheral infusion of IGF-I increases progenitor cell proliferation and selectively induces neurogenesis in the progeny of adult neural progenitor cells. This corresponds to a 78 +/- 17% (p < 0.001) increase in the number of new neurons in IGF-I-treated animals compared with controls.

Growth hormone increases connexin-43 expression in the cerebral cortex and hypothalamus.

Several studies indicate that systemic GH influences various brain functions. Connexin-43 forms gap junctions that mediate intercellular communication and establish the astroglial syncytium. We investigated the effects of peripheral administration of bovine GH (bGH) and recombinant human insulin-like growth factor I (rhIGF-I) on the expression of connexin-43 in the rat brain. Hypophysectomized female Sprague Dawley rats were substituted with cortisol (400 microg/kg x day) and L-T4 (10 microg/kg x day) and treated with either bGH (1 mg/kg x day) or rhIGF-I (0.85 mg/kg x day) for 19 days. The abundance of connexin-43 messenger RNA (mRNA) and protein in the brainstem, cerebral cortex, hippocampus, and hypothalamus was quantified by means of ribonuclease protection assays and Western blots. Treatment with bGH increased the amounts of connexin-43 mRNA and protein in the cerebral cortex and hypothalamus. No changes were found in the brainstem or hippocampus. Infusion of rhIGF-I did not affect connexin-43 mRNA or protein levels in any of the brain regions studied. These results show that administration of bGH increases the abundance of cx43 in specific brain regions, suggesting that GH may influence gap junction formation and thereby intercellular communication in the brain.

Delta-opioid receptors on astroglial cells in primary culture: mobilization of intracellular free calcium via a pertussis sensitive G protein.

Astrocytes in primary culture from rat cerebral cortex were probed concerning the expression of delta-opioid receptors and their coupling to changes in intracellular free calcium concentrations ([Ca2+]i). Fluo-3 or fura-2 based microspectrofluorometry was used for [Ca2+]i measurements on single astrocytes in a mixed astroglial-neuronal culture. Application of the selective delta-opioid receptor agonist, [D-Pen2, D-Pen5]-enkephalin (DPDPE), at concentrations ranging from 10 nM to 100 microM, induced concentration-dependent increases in [Ca2+]i (EC50 = 114 nM). The responses could be divided into two phases, with an initial spike in [Ca2+]i followed by either oscillations or a sustained elevation of [Ca2+]i. These effects were blocked by the selective delta-opioid receptor antagonist ICI 174864 (10 microM). The expression of delta-opioid receptors on astroglial cells was further verified immunohistochemically, using specific antibodies, and by Western blot analyses. Pre-treatment of the cells with pertussis toxin (100 ng/ml, 24 h) blocked the effects of delta-opioid receptor activation, consistent with a Gi- or Go-mediated response. The sustained elevation of [Ca2+]i was not observed in low extracellular Ca2+ and was partly blocked by nifedipine (1 microM), indicating the involvement of L-type Ca2+ channels. Stimulating neurons with DPDPE resulted in a decrease in [Ca2+]i, which may be consistent with the closure of the plasma membrane Ca2+ channels on these cells. The current results suggest a role for astrocytes in the response of the brain to delta-opioid peptides and that these opioid effects in part involve altered astrocytic intracellular Ca2+ homeostasis.

Extent of intercellular calcium wave propagation is related to gap junction permeability and level of connexin-43 expression in astrocytes in primary cultures from four brain regions.

Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cellular networks. This coupling is important for the propagation of intercellular calcium waves and for the spatial buffering of K+. Using the scrape-loading/dye transfer technique, we studied gap junction permeability in rat astrocytes cultured from four different brain regions. The cultures were shown to display regional heterogeneity with the following ranking of the gap junction coupling strengths: hippocampus = hypothalamus > cerebral cortex = brain stem. Similar relative patterns were found in connexin-43 messenger RNA and protein levels using solution hybridization/RNase protection assay and western blots, respectively. The percentages of the propagation area of mechanically induced intercellular calcium waves for cortical, brain stem and hypothalamic astrocytes compared with hippocampal astrocytes were approximately 77, 42, and 52, respectively. Thus, the extent of calcium wave propagation was due to more than just gap junctional permeability as highly coupled hypothalamic astrocytes displayed relatively small calcium wave propagation areas. Incubation with 5-hydroxytryptamine decreased and incubation with glutamate increased the calcium wave propagation area in hippocampal (67% and 170% of the control, respectively) and in cortical astrocytes (82% and 163% of the control, respectively). Contrary to hippocampal and cortical astrocytes, the calcium wave propagation in brain stem astrocytes was increased by 5-hydroxytryptamine incubation (158% of control), while in hypothalamic astrocytes, no significant effects were seen. Similar effects from 5-hydroxytryptamine or glutamate treatments were observed on dye transfer, indicating an effect on the junctional coupling strength. These results demonstrate a strong relationship between connexin-43 messenger RNA levels, protein expression, and gap junction permeability among astroglial cells. Furthermore, our results suggest heterogeneity among astroglial cells from different brain regions in intercellular calcium signaling and in its differential modulation by neurotransmitters, probably reflecting functional requirements in various brain regions.

Connexin43 mRNA and protein expression during postnatal development of defined brain regions.

Connexin43 (cx43) mRNA and protein were quantified in seven brain regions using RNase protection assays and Western blotting from postnatal day 3, 10, and 17, and adult Sprague-Dawley rats. Increases in cx43 mRNA abundance preceded strong increases in cx43 protein in the cerebral cortex, hippocampus, hypothalamus, and striatum, whereas smaller postnatal increases were seen in the cerebellum, brain stem, and olfactory bulbs.

Endothelin-1 decreases glutamate uptake in primary cultured rat astrocytes.

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide that is also known to induce a wide spectrum of biological responses in nonvascular tissue. In this study, we found that ET-1 (100 nM) inhibited the glutamate uptake in cultured astrocytes expressing the glutamate/aspartate transporter (GLAST); astrocytes did not express the glutamate transporter-1 (GLT-1). The V(max) and the K(m) of the glutamate uptake were reduced by 57% and 47%, respectively. Application of the ET(A) and ET(B) receptor antagonists BQ-123 and BQ-788 partly inhibited the ET-1-evoked decrease in the glutamate uptake, whereas the nonspecific ET receptor antagonist bosentan completely inhibited this decrease. Incubation of the cultures with pertussis toxin abolished the effect of ET-1 on the uptake. The ET-1-induced decrease in the glutamate uptake was independent of extracellular free Ca(2+) concentration, whereas the intracellular Ca(2+) antagonists thapsigargin and 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester abolished the effect of ET-1 on the glutamate uptake. Incubation with the protein kinase C (PKC) antagonist staurosporine, but not with the fatty acid-binding protein bovine serum albumin, prevented the ET-1-induced decrease in the glutamate uptake. These results suggest that ET-1 impairs the high-affinity glutamate uptake in cultured astrocytes through a G protein-coupled mechanism, involving PKC and changes in intracellular Ca(2+).