Search results for "STRAINS"

Distribution and induction of cytochrome P-450 and two cytochrome P-450-dependent monooxygenase activities in rat liver parenchymal cell subpopulatio…

1989

Liver parenchymal cells from the periportal and centrilobular zones differ in their morphological, biochemical and functional characteristics. In an effort to obtain fractions enriched in either periportal or centrilobular cells, isolated rat liver parenchymal cells were separated into five subpopulations by centrifugal elutriation. The mean diameters of the cells present in fractions I-V were 19.6, 21.1, 21.8, 22.7 and 23.5 micron, respectively. The content of cytochrome P-450 as well as benzphetamine N-demethylase and 7-ethoxyresorufin O-deethylase activities were higher in the larger parenchymal cells than in the smaller ones. After administration of phenobarbital the content of cytochro…

Regio- and stereoselective regulation of monooxygenase activities by isoenzyme-selective phosphorylation of cytochrome P450.

1989

The phosphorylation of the two major phenobarbital-inducible cytochrome P450 isoenzymes IIB1 and IIB2 was increased in hepatocytes by the action of the membrane permeating cAMP derivatives N6-dibutyryl-cAMP and 8-thiomethyl-cAMP. Under these conditions the dealkylation of 7-pentoxyresorufin, a selective substrate of cytochrome P450IIB1 and P450IIB2 was markedly reduced. 16 beta-Hydroxylation of testosterone which is catalyzed specifically only by cytochrome P450IIB1 and IIB2 was strongly reduced; for 16 alpha-hydroxylation which is also catalyzed by cytochrome P450IIB1 and IIB2 but additionally by 3 further cytochrome P450 isoenzymes, this reduction was less pronounced; for the oxidation of…

Studies on protein kinases involved in regulation of nucleocytoplasmic mRNA transport

1988

The rate of energy-dependent nucleoside triphosphatase (NTPase)-mediated nucleocytoplasmic translocation of poly(A)-containing mRNA [poly(A)+mRNA] across the nuclear envelope is thought to be regulated by poly(A)-sensitive phosphorylation and dephosphorylation of nuclear-envelope protein. Studying the phosphorylation-related inhibition of the NTPase, we found that phosphorylation of one polypeptide of rat liver envelopes by endogenous NI- and NII-like protein kinase was particularly sensitive to poly(A). This polypeptide (106 kDa) was also phosphorylated by nuclear-envelope-bound Ca2+-activated and phospholipid-dependent protein kinase (protein kinase C). Activation of kinase C by tumour-pr…

Binding of oral contraceptive progestogens to serum proteins and cytoplasmic receptor

1990

Abstract Some progestogens widely used in oral contraceptives are characterized at the level of high-affinity receptor binding as well as binding to sex hormone-binding globulin and corticosteroid-binding globulin. With regard to binding to sex hormone-binding globulin, gestodene, levonorgestrel, and to a lesser extent 3-ketodesogestrel (which is only formed from the prodrug desogestrel in the body), show a behavior that is manifested in the relatively high affinity to sex hormone-binding globulin, whereas desogestrel and norgestimate do not display any measurable affinity for this specific steroid-binding serum protein. Furthermore, levonorgestrel and gestodene dissociate very much more sl…

Precise annual changes in the numbers of "synaptic" ribbons and spherules in the rat pineal gland.

1988

Although pineal "synaptic" ribbons (SR) are frequently examined by means of quantitative electron microscopy, their functional significance remains unclear. The same is true for related structures—"synaptic" spherules (SPH). In the course of such studies, it has been noted that SR counts may differ from laboratory to laboratory. Because seasonal changes may play a role, a 2-year study was performed on male rats kept under routine laboratory conditions and killed at monthly intervals during daytime or nighttime. Both structures examined showed distinct day-night differences throughout the year, with higher numbers at night than during the day. There were significant annual changes in both S…

Release of [3H]acetylcholine from a modified rat phrenic nerve-hemidiaphragm preparation

1986

Two different preparations of the rat phrenic nerve-hemidiaphragm (whole nerve-muscle preparation, end-plate preparation) were used for studying synthesis and release of radioactive acetylcholine in the absence and presence of cholinesterase inhibitors. When the whole nerve-muscle preparation (110-180 mg) was incubated with [3H]choline, only small amounts of radioactive acetylcholine were synthesized within the tissue. Electrical nerve stimulation of the whole nerve-muscle preparation produced no increase in tritium outflow. Incubation of the end-plate preparation (16-29 mg) which was obtained after removal of most of the muscle mass led to the formation of large amounts of [3H]acetylcholin…

Effect of unbalanced diets on incorporation of δ-aminolevulinic acid into cytochrome P-450

1987

Abstract The in vivo syntheses of two liver microsomal cytochromes P-450 PB 3a , P-450 UT 50 [(1987) Eur. J. Biochem., submitted] ( M r 50 000, 52 000) have been estimated by measuring the specific activity 2 h after i.p. administration of δ-[ 3 H]aminolevulinic acid to male Sprague Dawley rats. The animals were fed either a standard rat chow (5% lard, 22% casein) or unbalanced diets (high lipid, 30% lard or low protein, 6% casein) with or without 50 ppm Phenoclor DP6. The high-lipid diet supported a more rapid body weight gain but had little impact on cytochrome P-450 content, expressed either per whole liver or per mg microsomal protein, and on the incorporation of the precursor into cyto…

Single and repeated treatment with chlordiazepoxide and sodium valproate and head-twitch responses induced in rats with rolipram, a potential antidep…

1989

Significant divergences between the temporal structure of the behavior in Wistar and in the spontaneously more anxious DA/Han strain of rats tested i…

2013

Abstract The aim of present research is to study the temporal structure of the behavior in two strains of rats with different basal level of emotionality. To this purpose, the temporal profile of the behavior in Wistar rat and in the spontaneously more anxious DA/Han strain was analyzed in the Elevated Plus Maze. Both quantitative and multivariate t-pattern analyses were carried out. In comparison with Wistar, DA/Han subjects showed a significant reduction of the permanence in open arm and a significant increase of the time spent in the central platform of the maze. Mean frequencies of each behavioral element showed significant modifications both in open and in closed arm. Multivariate t-pa…

Strain Differences in Open-Field and Elevated Plus-Maze Behavior of Rats Without and With Pretest Handling

1998

Behavior of two rat strains was analyzed with and without 1-week pretest handling. Male rats (150-200 g body weight) of the strains PVG/OlaHsd (PVG) and Hsd:Sprague-DawleySD (SPRD) were tested once in a standard open field and an enriched open field and twice in an elevated plus-maze. Behavioral analysis revealed significant differences between the two strains and differential effects of the pretest handling procedure. SPRD rats displayed higher levels of activity and exploratory behavior than the PVG rats, whereas PVG rats were obviously less anxious. One-week pretest handling had an "anxiolytic" effect and changed activity and exploration-related behavior of the animals in both strains. A…