The effects of melatonin and L-DOPA on the diurnal rhythms of free amino acids content in the rat retina.

The effects of melatonin and dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) intraperitoneal administration on the rhythms of free amino acids content in the retina of rats were studied. The authors found that the levels of those amino acids, which are protein constituents but not neurotransmitters in the rat retina, change diurnally with maximum at 3-6 h after light onset. Diurnal changes of Ala, Arg, Asn, Ile, Met, Ser, Trp, and Val content persisted in the retina of rats maintained at constant darkness.

Purine biosynthesis de novo in bovine retina: purification and characterization of amidophosphoribosyl transferase and phosphoribosyl pyrophosphate synthetase.

The ability of bovine retina to synthesize purines de novo is shown for the first time. Amidophosphoribosyl transferase (EC 2.4.

[Decreased content of non-heme iron in the blood of patients with peripheral tapetoretinal abiotrophy].

Measurement of non-heme iron in the sera of patients with peripheral tapetoretinal abiotrophy aged 10-72 years with stages I-IV of the disease showed a statistically significant (26-30%) decrease of this parameter in comparison with healthy controls. Total iron-binding capacity of the serum was unchanged. The results are discussed with regard for previous reports about changed iron homeostasis in animals with hereditary retinal degeneration (Campbell rats) and the role of iron in the development and formation of nervous tissues.

Membranes of retinal microsomes: a new protein of the microsomal monooxigenase system.

A new component, which substitutes cytochrome P-450 as an acceptor of reducing equivalents from NADPH-cytochrome P-450 reductase, was identified in the bovine retina microsomal monooxigenase system, which does not contain cytochrome P-450. This component is a non-heme iron-containing protein with molecular mass of 66 kDa. The properties of the protein from the bovine retina are similar to those of MIP, a non-heme iron-containing protein from the heart microsomal monooxigenase system, in which cytochrome P-450 was not identified, either.

[Changes in the electroretinogram of Campbell rats with the development of hereditary retinal degeneration].

We studied the dependence of amplitudes of a- and b-waves of electroretinogram on intensity of light stimulus in Campbell rats with inherited retinal degeneration. On 20-th-29-th day after birth the amplitude of these waves in Campbell rats is smaller than in Wistar rats. On 30-th-40-th day response significantly decreases, down to complete disappearance of reaction.

[Localization and causes of lipid peroxidation disorders in the rat cerebral cortex in the early stages of hereditary retinal degeneration].

It is established that previously observed increased rate of the induced lipid peroxidation in brain tissue of rats with hereditary retinal degeneration as compared with normal rats is due to the change of the rate of this process in the microsome cortex brain fraction and was not observed in the mitochondrial-synaptosomal and nuclear fractions. The content of nonheme iron ions in microsome cortex brain fraction of the Campbell rats is decreased by 35% and of the Fe ion was in the reduced form as compared with the Wistar rats. The ratio of Fe2+/Fe3+ in this fraction of the Campbell rats will be 5.

[Aminobenzoic acid derivatives as specific inhibitors of cyclic nucleotide phosphodiesterase in the rat uterus].

It is shown, that p-aminobenzoic acid and its derivatives (p-acetylaminobenzoic acid and p-aminobenzoic acid hydrazide) in the concentration of 10(-6) M are the potent inhibitors (40% below the control specimens) of the phosphodiesterase activity of cyclic nucleotides in the soluble fraction of the adult rat uterus. These drugs exerted no action on the adenylate cyclase activity in membrane fractions. The inhibition is only specific to the uterus enzyme and is not revealed for other tissues.

[The peptide activator of cyclic nucleotide phosphodiesterases: its effect on muscle contractile activity].

The presence of the peptide activator of cyclic nucleotide phosphodiesterase, which has been discovered previously in rat and calf myometrium, was studied in different rat tissues. The peptide was shown to present only in muscle tissues, except for intestinal tissue. In physiological experiments the peptide stimulated the contraction of rat uterine smooth muscle and diaphragmatic muscle.

Active sites of the cyclic GMP phosphodiesterase gamma-subunit of retinal rod outer segments.

Monoclonal antibodies were prepared to the gamma-subunit of the cGMP phosphodiesterase. One of them gamma p-1, suppresses the activation of phosphodiesterase through the alpha-subunit of transducin. The gamma-subunit fragment 24-45 rich in Arg and Lys residues is involved in gamma p-1 binding and is essential for the gamma-subunit interaction with transducin.

[The role of GTP-binding proteins in the olfactory reception of vertebrates].

The inhibitory effect of the non-hydrolyzable GTP analog Gpp (NH) p (10(-5)-10(-3) M) on the specific binding of some natural odorants (L-3H-amino acids, boar sex pheromone analog 5 alpha-3H-androstan-3-one) and sex hormones (17 beta-3H-estradiol, 3H-testosterone and 5 alpha-3H-dihydrotestosterone) to the olfactory receptors of some vertebrates (fish, frog, sow, rat) was found. Under the same experimental conditions Gpp (NH) p did not affect the high affinity binding of 5 alpha-3H-androstan-3-one to the sow respiratory tissue preparations. It was assumed that the changes in the specific binding of odorants in the presence of guanyl nucleotides can be a suitable test for the identification of true odorant receptors which conjugate with the system of olfactory transduction through G-proteins.

[Detection of peptide, an activator of cyclic nucleotide phosphodiesterases, in uterine tissue].

The soluble fraction of uterine tissue was found to contain a factor which is a potent activator of various cyclic nucleotide phosphodiesterases (with the exception of the retinal photoreceptor cell enzyme). The protein origin of this factor was established, using proteolysis, precipitation with trichloroacetic acid. The activator was purified by gel filtration on Sephadex G-25 and Biogel P-4 as well as by a highly effective liquid chromatography.

[Receptors of the olfactory cells: the problem of their identification and characteristics].

Own and some last literary data on the vertebrate olfactory receptors are summarized. Special attention is devoted to the identification of these receptors. The connection of these receptors with the proteins binding the guanosine triphosphate is demonstrated.

[Methylation of 3',5'-cGMP phosphodiesterase in retinal photoreceptor membranes].

It was found that the level of methylation of phosphodiesterase (EC 3.1.4.

[Influence of effectors of hormone-sensitive adenylate cyclase on the activation system of photostimulated cyclic nucleotide phosphodiesterase from outer rod segments].

The effect of preincubation of preparations of the outer segments of optic rods with the nonhydrolyzed analog GTP-guanilyl-5'-imidodiphosphate (Gpp(NH)p) and NaF, the combined effect of these agents as well as the action of (NH4)2SO4 (10-800 mM), MgSO4 (2-50 mM) and induction of peroxide oxidation of lipids are studied as applied to the catalytic activity of phosphodiesterase of cyclic nucleotides. Gpp(NH)p and NaF are shown to be tightly bound to GTP-binding proteins (G-proteins) of outer segments of optic rods, additional activation of phosphodiesterase in the presence of Gpp(NH)p being observed after preincubation with NaF and subsequent washing of the membrane. A problem on different binding sites of the ion F and Gpp(NH)p on G-proteins is discussed.