Hypericin fluorescence kinetics in the presence of low density lipoproteins: study on quail CAM assay for topical delivery.

There has been increasing interest in fluorescence-based imaging techniques in clinical practice, with the aim to detect and visualize the tumour configuration and the border with healthy tissue. Strong photodynamic activity of hypericin (Hyp) can be improved by various molecular transport systems (e.g. LDL). Our aim was to examine pharmacokinetics of Hyp in the presence of LDL particles on ex ovo chorioallantoic membrane (CAM) of Japanese quail with implanted TE1 tumour spheroids (human squamocellular carcinoma). Spheroids were implanted on CAM surface on embryonal day 7 and after 24 hours formulations of free Hyp and Hyp:LDL 100:1 and 200:1 were topically applied. All experimental formulations in the fluorescent image very well visualized the tumour spheroid position, with gradual increase of fluorescence intensity in 6-h observation period. LDL transportation system exhibited clear superiority in fluorescence pharmacokinetics than free Hyp formulation by increasing tumour-normal difference. Our experimental results confirm that Hyp and Hyp:LDL complex is potent fluorophore for photodynamic diagnosis of squamocellular carcinoma.

Photodynamic effect of hypericin after topical application in the ex ovo quail chorioallantoic membrane model.

Photosensitizing properties of hypericin are well known, and the chicken chorioallantoic membrane has previously been used to test photodynamic effects of hypericin and other substances. In our study the photodynamic effect of hypericin in the ex ovo quail chorioallantoic membrane model was evaluated. Steady-state and time-resolved fluorescence spectroscopy of hypericin solution in PEG-400 and its mixture in PBS was performed to assess and characterize the process of aggregation and disaggregation of hypericin during the drug formulation preparation. A therapeutical formulation (2 µg/g of embryo weight) was topically applied on CAM into the silicone ring. Hypericin was excited by diode laser with wavelength 405 nm, fluence rate 140 mW/cm2, and fluence 16.8 J/cm2. Hypericin in 100% PEG-400 exhibits typical fluorescence spectra with a maximum of about 600 nm, while hypericin 10% PEG-400 formulation exhibits almost no fluorescence. Time resolved spectra analysis showed fluorescence decay of hypericin in 100% PEG-400 solution with a mean lifetime of 5.1 ns and in 10% PEG 4.1 ns. Damage of quail chorioallantoic membrane vasculature after photodynamic therapy ranged from hemorrhage and vanishing of capillary vessels to thrombosis, lysis, and hemorrhage of larger vessels.The presented findings suggest that quail embryos can be used as a suitable model to test the effect of hypericin and other photodynamic compounds.

Kinetics and pharmacology of the D1- and D2-like dopamine receptors in Japanese quail brain.

Although the avian brain dopamine system and its functions have been studied much less than the mammalian one, there is an increasing interest in the role of dopamine and its receptors in a wide variety of motor, cognitive and emotional functions in birds with implications for basic research, medicine or agriculture. Pharmacological characterisation of the avian dopamine receptors has had little attention. In this paper we characterise the two classes of dopamine receptors in Japanese quail brain by radioligand binding techniques using [(3)H]SCH 23390 (D(1)) and [(3)H]spiperone (D(2)). Association, dissociation and saturation analyses showed that the binding of both radioligands is time- and concentration-dependent, saturable and reversible. Apparent dissociation constants determined for [(3)H]SCH 23390 and [(3)H]spiperone from concentration isotherms were 1.07 and 0.302 nM and the maximum binding capacities were 89.3 and 389.3 fmol per mg of protein, respectively. Using competitive binding studies with a spectrum of dopamine and other neurotransmitter receptor agonists/antagonists, the [(3)H]SCH 23390 and [(3)H]spiperone binding sites were characterised pharmacologically. Pharmacological profiles of quail dopamine receptors showed a high degree of pharmacological homology with other vertebrate dopamine receptors. The data presented extend the knowledge of kinetics and pharmacology of D(1)- and D(2)-like dopamine receptors in birds, provide data for avian psychopharmacological and comparative studies and represent an important complement to studies using cell expression systems.

The effects of feed restriction on plasma biochemistry in growing meat type chickens (Gallus gallus).

The effect of feed restriction on plasma hormones (triiodothyronine - T(3), thyroxine - T(4), and corticosterone), protein, lipid, carbohydrate, and mineral metabolism and activity of plasma enzymes (creatine kinase, alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase) were studied in meat type female chickens (Gallus gallus). Ad libitum fed birds were compared with those subjected to severe and moderate quantitative feed restriction from 16 to 100 days of age. Feed restriction elevated plasma T(4) and corticosterone levels and reduced T(3). A feed restriction-induced decrease was observed for plasma protein and albumin concentrations, but not for uric acid and creatinine. Total plasma lipids, triacylglycerols, cholesterol, high density lipids, and calcium were lower for the feed restricted chickens, in particular during the latter phase of the experiment. Concentrations of glucose and phosphorus were not altered by feeding treatment. Activity of alkaline phosphatase was significantly increased in restricted chicks from day 58. Significant changes of plasma biochemical parameters induced by severe and moderate quantitative feed restriction illustrate that limiting feed intake poses an intensive stress on meat type chickens during the rapid growth period. However, activities of creatine kinase, aspartate aminotransferase, and alanine aminotransferase were significantly higher in ad libitum fed chickens during this period. This elevation in enzymatic activity may be in response to tissue damage, indicating potential health and welfare problems also in ad libitum fed meat type chickens, resulting from selection for intensive growth.

Chicks from a high and low feather pecking line of laying hens differ in apomorphine sensitivity.

Proactive rodents show a larger behavioral response to apomorphine (APO) than reactive copers, suggesting a more sensitive DA system in proactive individuals. Previously, chicks from a high feather pecking (HFP) and low feather pecking line (LFP) have been suggested to display a proactive and reactive coping strategy, respectively. Therefore, at approximately 4 weeks of age, the behavior of 48 LFP and 48 HFP chicks in response to an APO injection was studied using an open field. Another objective of the present study was to determine whether behavioral variation (in an open field) between HFP and LFP birds, after APO injection, is also reflected by variation of D(1) and D(2) receptor densities in the brain. Receptor binding capacities were assessed by measuring specific binding of tritiated D(1) and D(2) receptor ligands in different regions of the brain of control HFP and LFP chicks. In the present study, it is shown that indeed HFP chicks display a more enhanced behavioral response to acute APO treatment (0.5 mg/kg BW) than LFP birds in an open field. This difference was not reflected by variation of D(1) and D(2) receptor densities in the brain between both lines.

Repeated apomorphine administration alters dopamine D1 and D2 receptor densities in pigeon basal telencephalon.

When pigeons are repeatedly administered a dose of apomorphine they show an increasing behavioral response, much as rodents do. In birds this expresses itself in an augmented pecking response. This sensitization is assumed to be largely due to a conditioning process. Here we present evidence that sensitization is accompanied by an alteration of the D(1) to D(2) dopamine receptor densities. An experimental group of pigeons was repeatedly injected with apomorphine, and a control group with saline. The basal forebrain tissue, known to be rich in dopamine receptors, was subjected to binding assays using tritiated specific D(1) and D(2) dopamine receptor antagonists. There was a trend towards an increase in D(1) and a significant decrease in D(2) receptor densities in apomorphine-treated birds compared to the saline-treated controls. We conclude that extended apomorphine treatment modifies the D(1) dopamine receptor density in the opposite manner to the D(2) dopamine receptor density.

Post-hatching dynamics of plasma biochemistry in free-living European starlings (Sturnus vulgaris).

This is the first study of plasma biochemical parameters in free-living altricial birds during an entire developmental period in a nest, represented by European starling (Sturnus vulgaris). Dynamics of postnatal changes from hatching until close to fledging (days 1 to 15) were registered. Parameters of protein metabolism represented by total proteins, albumin and globulin concentrations increased continuously during the observed developmental period. There were two peaks in uric acid concentration on days 5 and 11. To the contrary, the creatinine content did not change throughout the observed period and increased only on day 15. Creatine kinase activity gradually increased until day 11 and then fell before fledging. Parameters of lipid metabolism (concentration of total lipids, triacylglycerols and nonesterified fatty acids) in plasma increased gradually reaching a plateau between days 8 and 11 and then declined on day 15. The cholesterol concentration pattern was similar to maximum value on day 11, then consecutively decreased. Concentration of glucose increased until day 8 and remained unchanged until fledging. Whereas calcium reached the highest concentration during days 8 and 11, phosphorus peaked earlier on day 5. The activity of alkaline phosphatase was similar to the pattern found in calcium concentration. Presented data showed an increase in both protein and lipid metabolism during the phase of rapid growth. A remarkable decrease in parameters of lipid metabolism before fledging may reflect increased physical activity and changes in nutrition.