Influence of vitamins A, D3 and E status on post-mortem meat quality in steers under winter housing or pasture finishing systems.

We investigated the influence of Swedish recommended vitamins A, D3 and E supplementation levels on muscle tenderness and fatty acid (FA) composition under indoor or outdoor finishing programmes. Swedish Red breed steer calves were divided into vitamin supplemented (n = 12) and non-supplemented (n = 15) groups while on pasture prior to the finishing period. This trial began at the beginning of the winter housing period during which the steers were fed a 55 : 45 dry matter barley : grass silage diet indoors. The indoor finished group was comprised of vitamin supplemented (n = 6) and non-supplemented (n = 8) steers slaughtered after about 155 days on feed. Vitamin supplemented steers were provided with 100 g mineral supplement providing 400 000 IU vitamin A, 100 000 IU D3 and 3000 IU E daily as recommended for Swedish production practices. In spring, outdoor finished vitamin supplemented (n = 6) and non-supplemented (n = 7) steers grazed semi-natural grassland for an additional 120 days before slaughter. During pasture, vitamin supplemented steers had free-choice access to a mineral supplement containing vitamins A, D3 and E. The mineral supplement for the non-supplemented steers did not contain vitamins A, D3 and E and was provided at the same amount as the vitamin supplemented steers. Shear force values were similar between vitamin supplemented and non-supplemented steers after ageing 2, 7 and 14 days within indoor and outdoor finishing programmes. The shear force values had decreased by 14 days of ageing within all programmes. The µ- and m-calpain activity did not differ between vitamin supplemented and non-supplemented steers for either the indoor or outdoor finishing programmes. The calpastatin activity was higher for the indoor, vitamin supplemented steers. Indoor finished vitamin supplemented steers had a greater proportion of C18:1c-9 and total monounsaturated fatty acids, whereas the non-supplemented steers had a greater proportion of total saturated fatty acids. We concluded that the meat quality from steers not receiving vitamin supplementation was similar to that of steers receiving vitamins A, D3 and E supplementation at Swedish recommended levels under indoor and outdoor finishing programmes.

Manipulation of critical quality indicators and attributes in pork through vitamin E supplementation, muscle glycogen reducing finishing feeding and pre-slaughter stress.

The combination of a muscle glycogen reducing diet or a standard diet (control group) with normal (80 mg/kg) and high vitamin E levels (500 mg/kg) and exercise immediately prior to slaughter was used on 56 pigs to investigate the influence on meat quality indicators (pH and temperature) and attributes (drip loss, colour and Warner-Bratzler shear force). The drip loss was reduced in M. longissimus dorsi, M. biceps femoris and M. semimembranosus in pigs given the muscle glycogen reducing diet compared with the control groups, the greatest effect was seen in exercised pigs. These results can be explained by an early post mortem reduction in glycometabolism in pigs fed muscle glycogen reducing diets rather than by an increase in ultimate pH. Noticeably, high dietary vitamin E level increased muscle glycogen stores by about 10% on the day prior to slaughter but not on the day of slaughter in both dietary groups compared with the low dietary vitamin E level, which in fact reduced rather than improved the water-holding capacity, especially in pigs fed the standard diet.

Neurochemical studies with St. John's wort in vitro.

The effect of extracts and constituents of St. John's wort, Hypericum perforatum, at various CNS receptors were studied by radioligand binding techniques in order to determine a profile of pharmacological activity in vitro. Binding inhibition was examined for the G-protein coupled opioid, serotonin (5-HT), histamine, neurokinin and corticotropin releasing factor (CRF) receptors, for the steroid estrogen-alpha receptor and for the ligand-gated ionchannel GABA(A) receptor. Hypericin showed the most potent binding inhibiton of all tested constituents to human CRF1 receptor with an IC50 value of 300 nM. Preliminary GTPgamma35S binding studies to CRF1 coupled G-protein indicated an antagonistic action for hypericin. The acylphloroglucinole hyperforin failed to inhibit 125I-astressin binding to hCRF, receptor up to 10 microM. Hyperforin inhibited binding to opioid and serotonin (5-HT) receptors at IC50 values between 0.4 and 3 microM, while hypericin and pseudohypericin inhibited with weaker potency. The biflavonoid I3,II8-biapigenin inhibited 3H-estradiol binding to the estrogen-alpha receptor with an IC50 value of 1 microM. The inhibition of 3H-muscimol binding to the GABA(A) receptor is likely to be exclusively due to GABA present in the extract. We therefore hypothesize that additive or synergistic actions of several ditsinct compounds may be responsible for the beneficial antidepressant effect of St. John's wort.

Interaction of various Piper methysticum cultivars with CNS receptors in vitro.

Methanolic leaf and root extracts of the Hawaiian kava (Piper methysticum Forst.) cultivars, Mahakea, Nene, Purple Moi and PNG, were tested on binding affinities to CNS receptors including GABAA (GABA and benzodiazepine binding site), dopamine D2, opioid (mu and delta), serotonin (5-HT6 and 5-HT7) and histamine (H1 and H2). HPLC analysis was carried out in order to determine the amount of the main kavalactones kavain, 7,8-dihydrokavain, methysticin, 7,8-dihydromethysticin, yangonin and 5,6-demethoxyyangonin. The most potent binding inhibition was observed for leaf extracts to GABAA receptors (GABA binding site) with IC50 values of approximately 3 micrograms/ml, whereas root extracts were less active with IC50 values ranging from 5 micrograms/ml (Nene) to 87 micrograms/ml (Mahakea). Since the leaf extracts generally contained lower amounts of the kavalactones than the root extracts, there might exist additional substances responsible for these activities. Leaf extracts also inhibited binding to dopamine D2, opioid (mu and delta) and histamine (H1 and H2) receptors more potently than the corresponding root extracts with IC50 values ranging from 1 to 100 micrograms/ml vs. > or = 100 micrograms/l, respectively. Significant differences in the potential of binding inhibition were also observed between cultivars. Binding to serotonin (5-HT6 and 5-HT7) and benzodiazepine receptors was only weakly inhibited by both root and leaf extracts of all four cultivars. In conclusion, our investigation indicates that the GABAA, dopamine D2, opioid (mu and delta) and histamine (H1 and H2) receptors might be involved in the pharmacological action of kava extracts. Since the cultivars contained similar amounts of kavalactones, while their pharmacological activities differed markedly, other constituents may play a role in the observed activities. Additionally, leaves generally exhibited more potent binding inhibition than roots, therefore leaf of P. methysticum might be an interesting subject for further pharmacological studies.

A synthetic agonist at the orphanin FQ/nociceptin receptor ORL1: anxiolytic profile in the rat.

The biochemical and behavioral effects of a nonpeptidic, selective, and brain-penetrant agonist at the ORL1 receptor are reported herein. This low molecular weight compound [(1S,3aS)-8- (2,3,3a,4,5, 6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triaza- spiro[4. 5]decan-4-one] has high affinity for recombinant human ORL1 receptors and has 100-fold selectivity for ORL1 over other members of the opioid receptor family. It is a full agonist at these receptors and elicits dose-dependent anxiolytic-like effects in a set of validated models of distinct types of anxiety states in the rat (i.e., elevated plus-maze, fear-potentiated startle, and operant conflict). When given systemically, the compound has an efficacy and potency comparable to those of a benzodiazepine anxiolytic such as alprazolam or diazepam. However, this compound is differentiated from a classical benzodiazepine anxiolytic by a lack of efficient anti-panic-like activity, absence of anticonvulsant properties, and lack of effects on motor performance and cognitive function at anxiolytic doses (0.3 to 3 mg/kg i.p.). No significant change in intracranial self-stimulation performance and pain reactivity was observed in this dose range. Higher doses of this compound (>/=10 mg/kg) induced disruption in rat behavior. These data confirm the notable anxiolytic-like effects observed at low doses with the orphanin FQ/nociceptin neuropeptide given locally into the brain and support a role for orphanin FQ/nociceptin in adaptive behavioral fear responses to stress.

Extracts and constituents of Hypericum perforatum inhibit the binding of various ligands to recombinant receptors expressed with the Semliki Forest virus system.

Extracts, fractions and constituents of Hypericum perforatum were studied for in vitro receptor binding with various ligands to recombinant CNS receptors expressed with the Semliki Forest virus expression system. For this purpose we have prepared membranes of CHO cells with high density of several opioid, serotonin, estrogen, histamine, GABAA, neurokinin and metabotropic glutamate receptors, respectively. A lipophilic Hypericum fraction revealed relatively potent inhibition to the binding of the mu-, delta- and kappa-opioid and the 5-HT6 and 5-HT7 receptors. Moreover, Hypericum constituents such as the naphthodianthrones, hypericin and pseudohypericin, and the phloroglucinole hyperforin inhibited both binding to the opioid and serotonin receptors in the lower micromolar range. Estrogen binding was 50% inhibited by the biflavonoid I3,II8-biapigenin at micromolar concentration. The lipophilic Hypericum fraction provided a less potent inhibition of the neurokinin-1 receptor binding compared to the opioid and serotonin receptors. A total ethanolic Hypericum extract potently inhibited GABAA binding at approximately 3 micrograms/ml. This inhibition is however not specific to Hypericum, since extracts of plants like Valeriana officinalis and Passiflora incarnata showed similar inhibitions. Binding to neither histamine nor metabotropic glutamate receptors was affected by Hypericum extracts. These results support the hypothesis that several active constituents of Hypericum might in a synergistic way contribute to its antidepressant effect in the central nervous system.

Hypericum perforatum inhibits the binding of mu- and kappa-opioid receptor expressed with the Semliki Forest virus system.

The effects of Hypericum perforatum extracts on in vitro [3H]naloxone binding to the human mu- and rat kappa-opioid receptors were studied in chinese hamster ovary (CHO) cells using the Semliki Forest virus (SFV) expression system. Binding of [3H]naloxone to the mu- and kappa-opioid receptor was inhibited in the presence of Hypericum extracts showing IC50 values of approximately 25 and 90 micrograms/ml, respectively. In contrast, extracts of Valeriana officinalis did not inhibit binding to the mu-opioid receptor. Also, single constituents of H. perforatum like the flavonoids quercetin and kaempferol and the glycosilated flavonoid quercitrin did not inhibit [3H]naloxone binding to the mu-opioid receptor up to a concentration of 10 microM. The present in vitro data may suggest a new possible mechanism for the anti-depressant effect of H. perforatum.

Ionic permeability of, and divalent cation effects on, two ATP-gated cation channels (P2X receptors) expressed in mammalian cells.

1. Complementary DNAs for the ATP-gated ion channel subunits P2X1 (from human bladder) and P2X2 (from rat phaeochromocytoma (PC12) cells) were used to express the receptors in human embryonic kidney cells by stable transfection, and in Chinese hamster ovary cells by viral infection. 2. Membrane currents evoked by ATP were recorded by the whole-cell patch clamp method. The reversal potential of the current was measured with various intracellular and extracellular solutions and used to compute the relative permeability of the P2X receptor channels. 3. There was no difference between the two receptors with respect to their permeability to monovalent organic cations. The relative permeabilities (PX/PNa) were 2.3, 1.0, 1.0, 0.95, 0.72, 0.5, 0.29, 0.16, 0.04 and 0.03 for guanidinium, potassium, sodium, methylamine, caesium, dimethylamine, 2-methylethanolamine, tris(hydroxymethyl)-aminomethane, tetraethylammonium and N-methyl-D-glucamine, respectively (values for P2X2 receptor). 4. The calcium permeability of P2X1 receptors was greater than that of P2X2 receptors. Under biionic conditions (112 mM calcium outside, 154 mM sodium inside), PCa/PNa values were 3.9 and 2.2, respectively (corrected for ionic activities). 5. ATP-evoked currents in cells expressing the P2X2 receptor were strongly inhibited when the extracellular calcium concentration was increased (0.3-30 mM); the action of ATP could be restored by increasing the ATP concentration. ATP-evoked currents in cells expressing the P2X1 receptor were not inhibited by such increases in the extracellular calcium concentration.