Effects of adenosine 3′, 5′-cyclic monophosphate on thermoregulation in both rats and rabbits

Summary The effects of intraventricular administration of dibutyryl adenosine 3, 5-cyclic monophosphate (db cyclic AMP) on the thermoregulatory responses of unanesthetized rats and rabbits to different ambient temperatures (T_a) were assessed. Administration of db cyclic AMP (10–60 mM) produced dose-dependent hypothermia in both rats and rabbits at T_a 2–22 °C. The hypothermia in response to db cyclic AMP was due to decreased metabolic heat production and cutaneous vasodilatation. There was no change in respiratory evaporative heat loss. In contrast, in the heat (30–32 °C), db cyclic AMP administration produced dose-dependent hyperthermia in these animals. The hyperthermia was due to increased metabolism (due to muscular shivering) and decreased heat losses. The reduction in heat losses was shown by a decrease in both cutaneous circulation and respiratory evaporative heat loss. The data demonstrate that the thermoregulatory responses induced by central administration of db cyclic AMP are T_a-dependent.     

Cyclic adenosine 3′,5′monophosphate in cerebrospinal fluid of multiple sclerosis patients

Summary Cyclic adenosine 3,5monophosphate (cAMP) was assayed in CSF and plasma obtained from patients with multiple sclerosis. Decreased CSF cAMP levels were found in more than half of the patients while plasma cAMP was normal. The decrease is correlated significantly with the disability of the patient and with the progression of the disease. A low CSF cAMP level can be considered as prognostically unfavorable, particularly in the early stage of the disease. There was no correlation between the cAMP levels and the duration of the disease or with bouts and remissions. ACTH therapy did not normalize the decreased values. Obviously the decrease of CSF cAMP is related to the demyelination and not to the intensity of the pathological immunoreactions.

---

Zusammenfassung Es wurde das cyclische Adenosin-3,5monophosphat im Liquor von Patienten mit multipler Sklerose untersucht. Bei einem Teil der Patienten wurden auch die Vergleichswerte im Blutplasma bestimmt. Es zeigte sich bei mehr als der Hälfte der Patienten eine Verminderung der cAMP-Konzentration im Liquor bei normalem Plasmaspiegel. Diese cAMP-Verminderung erwies sich als signifikant abhängig von dem Schweregrad der Erkrankung bzw. der Erkrankungsprogredienz und ist besonders in frühen Erkrankungsfällen als prognostisch ungünstiges Zeichen anzusehen. Es fand sich kein Zusammenhang mit dem Krankheitsstadium, d.h. Schub bzw. Intervall, und mit der Erkrankungsdauer. Eine ACTH-Behandlung vermochte diese Verminderung der Werte nicht auszugleichen. Es wird die Wertigkeit dieser Befunde diskutiert.

     

Down-regulation of amyloid-β through AMPK activation by inhibitors of GSK-3β in SH-SY5Y and SH-SY5Y-AβPP695 cells

Glycogen synthase kinase 3β (GSK-3β) plays a critical role in the pathogenesis of Alzheimer's disease (AD), implicating amyloid-β (Aβ) production, neurofibrillary tangle formation, and neuronal apoptosis. The activation of 5' AMP-activated protein kinase (AMPK) has been linked to aberrant processing of amyloid-β protein precursor (AβPP), and AMPK signaling controls Aβ metabolism. It is possible that GSK-3β regulated the activation of the AMPK pathway. To test this hypothesis, the influence of GSK-3β on the expression of AβPP cleavage enzyme (BACE), Aβ, and AMPK in the SH-SY5Y and AβPP695 cells line through three inhibitors of GSK-3β was analyzed. Expression of Aβ, AMPK, and pAMPK172 was measured by Western blot, and BACE was tested by Western blot and RT-PCR. This study demonstrated that suppression of GSK-3β activity, through specific inhibitors, dramatically down-regulated Aβ generation in human SH-SY5Y and SH-SY5Y-AβPP695 cells by enhancing AMPK activity to down-regulate Aβ. These results suggest GSK-3β inhibitors may be promising agents in the prevention and treatment of AD.     

Mu-opioid ([3H]DAGO) binding in slices of rat brain: Inhibition by sodium ions,guanyl-5′-yl imidodiphosphate and by the adrenergic neurotoxins DSP4 and xylamine

We have characterized and quantified the specific binding of the μ-agonist [³H] DAGO to 300 μM slices of hypothalamus and cerebral cortex. The receptors have many of the opioid characteristics previously demonstrated in homogenate assays. Binding is reversible, saturable, stereospecific and of high affinity. The δ-opioids DTLET and DSLET are 36- and 30-fold respectively, less effective than DAGO in competing for the binding site. Assays can be routinely performed in the presence of physiological concentrations of sodium, though in TRIS buffer the affinity and the number of receptors is increased. Protection of the ligand against proteolytic degradation is unnecessary. Unexpectedly, we observed that GppNHp inhibits [³H] DAGO binding to brain slices. This suggests an allosteric modification of the μ-receptor in the membranes of intact cells. The μ-receptors are also blocked by the adrenergic neurotoxins DSP4 and xylamine. This re-emphasizes our contention that care should be exercised in the use of these drugs. The technique is simple, rapid and involves minimal disruption of tissue. It should provide new opportunities for the study of cell surface opioid receptor subtypes in intact tissue.     

Effect of IFN-ß therapy on the frequency and function of CD4+CD25+ regulatory T cells and Foxp3 gene expression in relapsing–remitting multiple sclerosis (RRMS): A preliminary study

Interferon-ß (IFN-ß) is an immunomodulatory drug of choice to control relapsing–remitting multiple sclerosis (RR-MS), although its function is still unclear. A reduced suppressive function of CD4⁺CD25⁺ regulatory T cells (T_reg) has been shown in RR-MS patients. In this study, to understand the effect of IFN-ß on CD4⁺CD25⁺ regulatory T cells, we analyzed the frequency and function of these cells and Foxp3 gene expression before and after treatment.We evaluated the frequency and function of CD4⁺CD25⁺Foxp3⁺ regulatory T cells by flow cytometry and co-culture inhibition test respectively and gene expression of Foxp3 by real-time PCR in a longitudinal follow-up study in 18 relapsing–remitting MS patients. Our data revealed that IFN-ß significantly improved frequency and suppressive function of T_reg cells (P < 0.05) without any significant effect on gene expression of Foxp3 after 6 months. The results of the present study indicate that IFN-ß therapy in some of patients with RR-MS may restore function of regulatory T cells and control the unchecked immune cascade activity. Larger longitudinal studies on more MS patients are required to confirm our findings.