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Expression of the type 1 metalloproteinase in the rat hippocampus after the intracerebroventricular injection of beta-amyloid peptide (25-35)

100%

Ierusalimsky V. N. , Kuleshova E. P. , Balaban P. M.

nr 4

The expression of matrix metalloproteinase of the first type was studied in frontal sections of the adult rat brain one month after a single intracerebroventricular injection of P-amyloid peptide (25-35), which is known to be a well-known model of the development of Alzheimer's disease. Brain sections were stained immunocytochemically to detect MMP-1 expression, and histologically to reveal the state of hippocampal neurons. Administration of P-amyloid peptide induced a significant degeneration of cells in the dorsal hippocampus. This was demonstrated by a significant decrease in the total number of cells and by the appearance of acidophilic neurons of altered (often triangular) shape. Altered cells were most often found in the hippocampal field CA3, and in a smaller quantity in the CA1 field. MMP-1-like immunoreactivity was found in the same hippocampal areas, the staining being restricted to the cells of altered shape (staining of somata and primary neurites). The data suggest possible involvement of the type 1 metalloproteinase in the development of Alzheimer's disease.

Expansion of the Golgi apparatus in rat cerebral cortex following intracerebroventricular injections of streptozotocin

84%

Grieb P. , Kryczka T. , Fiedorowicz M. , Frontczak-Baniewicz M. , Walski M.

nr 4

Effect of cerebral ventricles perfusion with morphiceptin and met-enkephalin on trigemino-hypoglossal reflex in rats

84%

Zubrzycka M. , Fichna J. , Janecka A.

nr 4,2

Opioids administered by intracerebroventricular injections produce analgesic responses in rats. The present study was undertaken to investigate the effects of a highly selective m-opioid receptor ligand morphiceptin on trigemino-hypoglossal reflex in rats. The analgesic effect of morphiceptin was compared with another opioid peptide, Met-enkephalin. With the experimental settings used in this study, we have demonstrated that both morphiceptin and Met-enkephalin show significant dose-dependent analgesic effects after i.c.v. administration in rats as assayed by trigemino-hypoglossal reflex test. The antinociceptive response to Met-enkephalin was short lasting and was observed 10 to 15 min after i.c.v. perfusion. Morphiceptin had a relatively longer duration of antinociceptive action, the effect was observed 20- 50 min after i.c.v. perfusion. Neither morphiceptin nor Met-enkephalin produced antinociception after peripheral injections. The results of the present study indicate that both tested peptides act at µ-opioid receptors situated in the central nervous system. They also suggest that µ-opioid receptors present in the central nervous system are an important element of the trigemino-hypoglossal reflex arc. For that reason selective m-opioid receptor ligands, like morphiceptin, inhibit the reflex more significantly.

Centrally applied ghrelin affects feeding dynamics in male rats

67%

Nesic D. M. , Stevanovic D. M. , Ille T. , Petricevic S. , Masirevic-Draskovic G. , Starcevic V. P.

nr 3

489-500

Ghrelin is 28-amino acid peptide, which is produced mainly in the stomach. Since plasma ghrelin are strictly dependent on food intake, this hormone has significant effects on appetite and energy balance. The aim of this investigation was to examine the effects of centrally applied ghrelin on feeding dynamism by measuring the approaches to food container and the amount of food and water intake within 2 hours immediately after ghrelin or PBS injections. Body weight was obtained daily, while ending retroperitoneal (RP) and epididymal (EPI) white adipose tissue (WAT) contents as well as blood levels of leptin and insulin were measured. Five injections of rat ghrelin or PBS (n = 8 per group) were administered once per day (1 µg = 0.15 nmol of ghrelin in 5 µL of PBS), into lateral cerebral ventricle (ICV) of free feeding adult male rats. Results showed that in the first and the second 30-min intervals number of approaches to food container were significantly increased already after the 2nd ICV ghrelin application (p < 0.05), by 50% and 67% respectively, in comparison with control rats. Centrally applied ghrelin increased body weight after the 2nd injection till the end of treatment (p < 0.05), which was followed by increased food and water intake (p < 0.05). At the end of treatment, RP and EPI WAT contents were increased (by 221%, p < 0.01 and 82%, p < 0.05, respectively). Serum insulin levels were elevated (by 41%, p < 0.05) while serum leptin levels were decreased (by 75%, p < 0.05). These data and the available literature strongly support the opinion that repetitive subnanomolar doses of central ghrelin administration play essential role in food initiation and feeding dynamics in freely feeding adult male rats.