An alteration in the lateral geniculate nucleus of experimental glaucoma monkeys: in vivo positron emission tomography imaging of glial activation

We examined lateral geniculate nucleus (LGN) degeneration as an indicator for possible diagnosis of glaucoma in experimental glaucoma monkeys using positron emission tomography (PET). Chronic intraocular pressure (IOP) elevation was induced by laser trabeculoplasty in the left eyes of 5 cynomolgus monkeys. Glial cell activation was detected by PET imaging with [(11)C]PK11195, a PET ligand for peripheral-type benzodiazepine receptor (PBR), before and at 4 weeks after laser treatment (moderate glaucoma stage). At mild, moderate, and advanced experimental glaucoma stages (classified by histological changes based on the extent of axonal loss), brains were stained with cresyl violet, or antibodies against PBR, Iba-1 (a microglial marker), and GFAP (an activated astrocyte marker). In laser-treated eyes, IOP was persistently elevated throughout all observation periods. PET imaging showed increased [(11)C]PK11195 binding potential in the bilateral LGN at 4 weeks after laser treatment; the increase in the ipsilateral LGN was statistically significant (P<0.05, n = 4). Immunostaining showed bilateral activations of microglia and astrocytes in LGN layers receiving input from the laser-treated eye. PBR-positive cells were observed in LGN layers receiving input from laser-treated eye at all experimental glaucoma stages including the mild glaucoma stage and their localization coincided with Iba-1 positive microglia and GFAP-positive astrocytes. These data suggest that glial activation occurs in the LGN at a mild glaucoma stage, and that the LGN degeneration could be detected by a PET imaging with [(11)C]PK11195 during the moderate experimental glaucoma stage after unilateral ocular hypertension. Therefore, activated glial markers such as PBR in the LGN may be useful in noninvasive molecular imaging for diagnosis of glaucoma.     

Role of xanthine oxidase in delayed lipid peroxidation in rat liver induced by acute exhausting exercise

The aim of this study was to examine whether xanthine oxidase (XOD)-derived hepatic oxidative damage occurs in the main not during but following strenuous exercise. The degree of damage to hepatic tissue catalyzed by XOD was investigated immediately and 3 h after a single bout of exhausting exercise, in allopurinol and saline injected female Wistar rats. Allopurinol treatment resulted in increased hypoxanthine and decreased uric acid contents in the liver compared with the saline treated group, immediately and 3 h after the exercise. Analysis immediately after the exercise showed no changes in hepatic hypoxanthine, uric acid, and thiobarbituric acid-reactive substance (TBARS) contents in the saline treated group, when compared with the resting controls. However, significant increases in uric acid contents in the saline treated livers were observed 3 h after the exercise, relative to the controls. Hepatic TBARS content in the saline treated group were markedly greater than those in both the control and allopurinol treated groups after 3 h of recovery following the exercise. It was concluded that a single bout of exhausting exercise may impose XOD-derived hepatic oxidative damage, primarily during the recovery phase after acute severe exercise.     

Superoxide radical- and peroxynitrite-scavenging activity of anthocyanins; structure-activity relationship and their synergism

Antioxidant activities of 15 purified bilberry anthocyanins together with pelargonidin 3-O-beta-D-glucopyranoside and 4'-O-methyl delphinidin 3-O-beta-D-glucopyranoside (MDp 3-glc), the major metabolite of delphinidin 3-O-beta-D-glucopyranoside (Dp 3-glc), were evaluated in order to study the structure-antioxidant activity relationship and any synergism among them in the mixture. Both aglycone structure and the attached sugar moiety affected the O*2- and ONOO- -scavenging activities, although the effect of the attached sugar moiety was smaller than that of the aglycone structure. The potency of activity toward the superoxide radical was in the following order: delphinidin > petunidin > malvidin =approximately cyanidin>(+)-catechin > peonidin > pelargonidin. The activity toward ONOO- was: delphinidin > cyanidin =approximately petunidin > malvidin =approximately (+)-catechin > peonidin > pelargonidin. It was confirmed that methylation of 4'-OH markedly reduced the antioxidant activity of anthocyanin. Further, it was revealed that synergism occurred in both - and ONOO- -scavenging activities among the anthocyanins in the mixture.     

Human brain acyl-CoA hydrolase isoforms encoded by a single gene

Acyl-CoA hydrolases are a group of enzymes that catalyze the hydrolysis of acyl-CoA thioesters to free fatty acids and CoA-SH. The human brain acyl-CoA hydrolase (BACH) gene comprises 13 exons, generating several isoforms through the alternative use of exons. Four first exons (1a-1d) can be used, and three patterns of splicing occur at exon X located between exons 7 and 8 that contains an internal 3(')-splice acceptor site and creates premature stop codons. When examined with green fluorescent protein-fusion constructs expressed in Neuro-2a cells, the nuclear localization signal encoded by exon 9 was functional by itself, whereas the whole structure was cytosolic, suggesting nuclear translocation of the enzyme. This was consistent with dual staining of the cytosol and nucleus in certain neurons by immunohistochemistry using anti-BACH antibody. The mitochondrial targeting signals encoded by exons 1b and 1c were also functional and directed mitochondrial localization of BACH isoforms with the signals. Although BACH mRNA containing the sequence derived from exon 1a, but not exon X, was exclusively expressed in human brain, these results suggest that the human BACH gene can express long-chain acyl-CoA hydrolase activity in multiple intracellular compartments by generating BACH isoforms with differential localization signals to affect various cellular functions that involve acyl-CoAs.     

A new class of pentapeptide KISS1 receptor agonists with hypothalamic–pituitary–gonadal axis activation

The kisspeptin (Kp, Kp-54, metastin)/KISS1R system plays crucial roles in regulating the secretion of gonadotropin-releasing hormone. Continuous administration of nonapeptide Kp analogs caused plasma testosterone depletion, whereas bolus administration caused strong plasma testosterone elevation in male rats. To develop a new class of small peptide drugs, we focused on stepwise N-terminal truncation of Kp analogs and discovered potent pentapeptide analogs. Benzoyl-Phe-azaGly-Leu-Arg(Me)-Trp-NH₂ (16) exhibited high agonist activity for KISS1R and excellent metabolic stability in rat serum. A single injection of a 4-pyridyl analog (19) at the N-terminus of 16 into male Sprague Dawley rats caused a robust increase in plasma luteinizing hormone levels, but unlike continuous administration of nonapeptide Kp analogs, continuous administration of 19 maintained moderate testosterone levels in rats. These results indicated that small peptide drugs can be successfully developed for treating sex hormone deficiency.     

DNA packaging proteins Glom and Glom2 coordinately organize the mitochondrial nucleoid of Physarum polycephalum

Mitochondrial DNA (mtDNA) is generally packaged into the mitochondrial nucleoid (mt-nucleoid) by a high-mobility group (HMG) protein. Glom is an mtDNA-packaging HMG protein in Physarum polycephalum. Here we identified a new mtDNA-packaging protein, Glom2, which had a region homologous with yeast Mgm101. Glom2 could bind to an entire mtDNA and worked synergistically with Glom for condensation of mtDNA in vitro. Down-regulation of Glom2 enhanced the alteration of mt-nucleoid morphology and the loss of mtDNA induced by down-regulation of Glom, and impaired mRNA accumulation of some mtDNA-encoded genes. These data suggest that Glom2 may organize the mt-nucleoid coordinately with Glom.