The cerebral serotonin (5-HT) system shows distinct differences in obesity compared with the lean state. Here, it was investigated whether serotonergic neurotransmission in obesity is a stable trait or changes in association with weight loss induced by Roux-in-Y gastric bypass (RYGB) surgery. In vivo cerebral 5-HT2A receptor and 5-HT transporter binding was determined by positron emission tomography in 21 obese [four men; body mass index (BMI), 40.1 ± 4.1 kg/m(2)] and 10 lean (three men; BMI, 24.6 ± 1.5 kg/m(2)) individuals. Fourteen obese individuals were re-examined after RYGB surgery. First, it was confirmed that obese individuals have higher cerebral 5-HT2A receptor binding than lean individuals. Importantly, we found that higher presurgical 5-HT2A receptor binding predicted greater weight loss after RYGB and that the change in 5-HT2A receptor and 5-HT transporter binding correlated with weight loss after RYGB. The changes in the 5-HT neurotransmission before and after RYGB are in accordance with a model wherein the cerebral extracellular 5-HT level modulates the regulation of body weight. Our findings support that the cerebral 5-HT system contributes both to establish the obese condition and to regulate the body weight in response to RYGB.
Erythropoietin (EPO) has demonstrated neuroprotective effects against traumatic brain injury (TBI), but the underlying mechanisms remain unclear. The signaling pathway of an antioxidant transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2), has been shown in our previous studies to play an important role in protecting mice from TBI-induced secondary brain injury. The present study explored the effect of recombinant human erythropoietin (rhEPO) on cerebral activation of the Nrf2 signaling pathway and secondary brain injury in mice after TBI. Adult male ICR mice were randomly divided into three groups: (1) Sham group; (2) TBI group; and (3) TBI+rhEPO group (n = 12 per group). Closed head injury was performed using Hall's weight-dropping method. rhEPO was administered at a dose of 5,000 IU/kg at 30 min after TBI. Brain samples were extracted at 24 hr after the trauma. The treatment with rhEPO markedly up-regulated the mRNA expression and activities of Nrf2 and its downstream cytoprotective enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1). Administration of rhEPO also significantly ameliorated the secondary brain injury, as shown by decreased severity of neurological deficit, brain edema, and cortical apoptosis. In summary, post-TBI rhEPO administration induces Nrf2-mediated cytoprotective responses in the injured brain, and this may be a mechanism whereby rhEPO improves the outcome following TBI.
o-Aminoazotoluene was more potent than 3'-methyl-4-dimethylaminoazobenzene in modulating glucocorticoid induction of tyrosine aminotransferase and DNA-binding activity of FOXA (HNF3) in 12-day-old ICR mice. In adult animals, induction of tyrosine aminotransferase and FOXA activity were modulated by o-aminoazotoluene, while 3'-methyl-4-dimethylaminoazobenzene was ineffective. Our results suggest that FOXA proteins determine glucocorticoid induction of tyrosine aminotransferase in mice (similarly to rats).
Using quantitative receptor autoradiography, we assessed binding site densities and distribution patterns of glutamate, GABA(A), acetylcholine (ACh), and monoamine receptors in the hippocampus of 32-month-old Fischer 344/Brown Norway rats. Prior to autoradiography, the rats were divided into two groups according to their retention performance in a water maze reference memory task, which was assessed 1 week after 8 days of daily maze training. The animals of the inferior group showed less long-term retention of the hidden-platform task but did not differ from superior rats in their navigation performance during place training and cued trials. The decreased retention performance in the group of inferior learners was primarily accompanied by increased alpha(1)-adrenoceptors in all hippocampal subregions under inspection (CA1-CA4 and dentate gyrus), while elevated alpha(2)-adrenoceptor binding was observed in the CA1 region and DG. Furthermore, inferior learners had higher NMDA binding in the CA2 and CA4 and increased 5-HT(1A) binding sites in the CA2, CA3, and CA4 region. No significant differences between inferior and superior learners were evident with regard to AMPA, kainate, GABA(A), muscarinergic M(1), dopamine D(1), and 5-HT(2) binding densities in any hippocampal region analyzed. These results show that increased NMDA, 5-HT(1A), and alpha-adrenoceptor binding in the hippocampus is associated with a decline in spatial memory. The increased receptor binding observed in the group of old rats with inferior maze performance might be the result of neural adaptation triggered by age-related changes in synaptic connectivity and/or synaptic activity.
The self-assembly of Aß peptides into a range of conformationally heterogeneous amyloid states represents a fundamental event in Alzheimer's disease. Within these structures oligomeric intermediates are considered to be particularly pathogenic. To test this hypothesis we have used a conformational targeting approach where particular conformational states, such as oligomers or fibrils, are recognized in vivo by state-specific antibody fragments.
We show that oligomer targeting with the KW1 antibody fragment, but not fibril targeting with the B10 antibody fragment, affects toxicity in Aß-expressing Drosophila melanogaster. The effect of KW1 is observed to occur selectively with flies expressing Aß(1-40) and not with those expressing Aß(1-42) or the arctic variant of Aß(1-42) This finding is consistent with the binding preference of KW1 for Aß(1-40) oligomers that has been established in vitro. Strikingly, and in contrast to the previously demonstrated in vitro ability of this antibody fragment to block oligomeric toxicity in long-term potentiation measurements, KW1 promotes toxicity in the flies rather than preventing it. This result shows the crucial importance of the environment in determining the influence of antibody binding on the nature and consequences of the protein misfolding and aggregation.
While our data support to the pathological relevance of oligomers, they highlight the issues to be addressed when developing inhibitory strategies that aim to neutralize these states by means of antagonistic binding agents.
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation. schultz@nioch.nsc.ru
Fifteen 2,4-dioxaspiro[5.5]undecane ketone and 2,4-dioxa-spiro[5.5]undec-8-ene (spiroundecane(ene)) derivatives were synthesized using the Diels-Alder reaction. Inhibition of human immunodeficiency virus integrase (IN) was examined. Eight spiroundecane(ene) derivatives inhibited both 3'-processing and strand transfer reactions catalyzed by IN. SAR studies showed that the undecane core with at least one furan moiety is preferred for IN inhibition. Moreover, crosslinking experiments showed that spiroundecane derivatives did not affect IN-DNA binding at concentrations that block IN catalytic activity, indicating spiroundecane derivatives inhibit preformed IN-DNA complex. The moderate toxicity of spiroundecane(ene) derivatives encourages the further design of therapeutically relevant analogues based on this novel chemotype of IN inhibitors.
It was shown that 30-50% ethanol or 40-70% dimetilsulfoxide could efficiently induce in vitro transformation of specific monoclonal antibodies (mAbs) into non-specific polyreactive immunoglobulins (PRIG). Intravenous injection 0.4 ml of FeSO4-EDTA mixture (60 and 30 mkM respectively) could induce increase of PRIG reactivity in the blood-stream. Intramuscle injection of either 0.1 ml of 40% ethanol, or 0.1 ml of FeSO4-EDTA mixture into muscle of hind limb of C57B1 mice leads to the substantial binding of circulated immunoglobulins to the blood vessels of the muscle. The similar effect could also be induced by ischemia/reperfusion of mice hind limb. In the case of intravenous injection of specific to ovalbumin biotinilated mAbs, the subsequent intramuscle injection of 0.1 ml of 40% ethanol induces apparent transformation of these mAbs into PRIG and their binding to the blood vessels. Intramuscle injection of 0.1 ml of FeSO4-EDTA mixture induces less than ethanol though noticeable effect. The obtained data have shown that cord-blood circulating specific antibodies could be transformed into PRIG at some conditions in vivo. If so, this process might play an important role in the organism defence against infections but could, probably, facilitate the development of atherosclerosis, cardiac infarct, cerebral stroke or tumors.
