Effects of caffeic and chlorogenic acids on the rat skeletal system.

OBJECTIVE: Caffeic acid, predominantly as esters linked to quinic acid (chlorogenic acids), is a phenolic acid present at high levels in coffee. The aim of the study was to investigate effects of caffeic and chlorogenic acids on the skeletal system of female rats with normal estrogen levels and estrogen-deficient. MATERIALS AND METHODS: Caffeic acid (5 and 50 mg/kg p.o. daily) and chlorogenic acid (100 mg/kg p.o. daily) were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized mature Wistar rats, and their effects were compared with appropriate controls. Moreover, estradiol (0.2 mg/kg p.o. daily) was administered to ovariectomized rats. Bone turnover markers, mass, mineralization and mechanical properties were examined. RESULTS: Although caffeic acid at a low dose exerted some unfavorable effects on the skeletal system, at high doses, caffeic and chlorogenic acids slightly increased mineralization in the tibia and improved mechanical properties of the femoral diaphysis (compact bone). Unlike estradiol, they did not counteract the worsening of the tibial metaphysis bone strength (cancellous bone) and increases in osteocalcin concentration induced by estrogen deficiency. CONCLUSIONS: High doses of the phenolic acids slightly favorably affected the rat skeletal system independently of the estrogen status.

Effects of fenugreek (Trigonella foenum-graecum L.) seed on bone mechanical properties in rats.

BACKGROUND AND AIM: An example of a medicinal plant with numerous potential activities is fenugreek (Trigonella foenum-graecum L.). The aim of the present study was to investigate the effects of fenugreek seed on bone mechanical properties in rats with normal and decreased estrogen level (developing osteoporosis). MATERIALS AND METHODS: The experiments were carried out on 3-month-old non-ovariectomized (NOVX) and ovariectomized (OVX) Wistar rats, divided into control rats, rats receiving pulverized fenugreek seed (1% in the diet) and rats receiving fenugreek seed extract standardized for 4-hydroxy-L-isoleucine (50 mg of 4-hydroxy-L-isoleucine/kg p.o. daily) for 4 weeks. Serum bone turnover markers, bone mineralization and mechanical properties were examined. RESULTS: Fenugreek seed added to food did not significantly affect bone mineralization and serum turnover markers, independently of the estrogen status. It tended to increase the strength of the tibial metaphysis (cancellous bone) in NOVX rats, and increased the strength of the femoral diaphysis (compact bone) in OVX rats. The fenugreek seed extract did not affect the skeletal system of NOVX rats, and significantly worsened mineralization of the vertebra in OVX rats, decreased due to estrogen deficiency. CONCLUSIONS: Low dietary intake of fenugreek seed may exert slight favorable skeletal effects, whereas at high doses it may damage the skeletal system.

Effect of concurrent administration of alendronate sodium and retinol on development of changes in histomorphometric parameters of bones induced by ovariectomy in rats.

Retinol is a commonly used vitamin, especially by elderly people. Alendronate sodium, an aminobisphosphonate, is a potent antiresorptive drug used in the treatment of osteoporosis in postmenopausal women. Frequently, alendronate sodium and retinol are used concurrently. There are no reports on the interaction between alendronate sodium and retinol. The aim of the present study was to investigate the effect of concurrent administration of alendronate sodium and retinol on bone remodeling in ovariectomized rats. The histomorphometric parameters of long bones were studied. The experiments were carried out on 3-month-old Wistar rats, divided into 7 groups: I (C) - sham operated control rats, II (OVX) - ovariectomized control rats, III (OVX + ALN) - ovariectomized rats + alendronate sodium (3 mg/kg po), IV (OVX + R-1) - ovariectomized rats + retinol (700 IU/kg po), V (OVX + R-2) - ovariectomized rats + retinol (3500 IU/kg po), VI (OVX + ALN + R-1) - ovariectomized rats + alendronate sodium (3 mg/kg po) + retinol (700 IU/kg po), VII (OVX + ALN + R-2) - ovariectomized rats + alendronate sodium (3 mg/kg po) + retinol (3500 IU/kg po). The drugs were administered to the rats daily by oral gavage (alendronate sodium in the morning, retinol in the afternoon) for 28 days. Body mass gain, bone mass, mineral content in the tibia, femur and L-4 vertebra, histomorphometric parameters of the right tibia (width of osteoid, periosteal and endosteal transverse growth, area of the transverse cross section of the bone marrow cavity and the cortical bone) and the right femur (width of epiphyseal and metaphyseal trabeculae, width of epiphyseal cartilage) were studied. Bilateral ovariectomy induced osteopenic skeletal changes in mature female rats. Alendronate sodium administered at a dose of 3 mg/kg po daily inhibited the development of changes induced by ovariectomy in the skeletal system of rats. Retinol, especially administered at the dose of 3500 IU/kg daily, intensified the changes in the osseous system caused by estrogen deficiency in rats. Retinol administered concurrently with alendronate sodium attenuated the antiresorptive effect of alendronate sodium on the skeletal system in ovariectomized rats.

Effects of doxycycline on mechanical properties of bones in rats with ovariectomy-induced osteopenia.

Tetracyclines have been reported to inhibit bone resorption and intensify bone formation. The aim of the present study was to investigate the effects of doxycycline (20 mg/kg PO daily for 28 days) on bone mechanical properties in bilaterally ovariectomized and sham-operated rats. The experiment was carried out on 3-month-old Wistar rats. Mechanical properties of the whole femur (extrinsic stiffness, ultimate and breaking load, deformation caused by applied load) and the femoral neck (load at fracture) as well as bone mass and bone mineral content in the tibia, femur, and L4 vertebra were examined. Bilateral ovariectomy resulted in decreases in bone mineral content/bone mass ratio and worsening of mechanical properties of the femoral neck. The changes were counteracted by doxycycline. Doxycycline reversed the effect of ovariectomy on load at fracture of the femoral neck. Doxycycline did not significantly affect the mechanical properties of bones in the sham-operated rats.

Effects of alpha-Escin on mechanical features of the femoral bone in rats with experimental post-steroid osteopenia.

The aim of the present study was to investigate the effects of alpha-escin on the experimental prednisolone-induced osteopenia. The experiments were carried out on male Wistar rats of initial body mass 240-310 g, divided into 4 groups (n = 6): I (C)-control, II (E)-alpha-Escin, III (P)-Prednisolone, IV (E + P)-Prednisolone + alpha-escin. Prednisolone (5 mg/kg i.m. daily) and/or alpha-escin (100 mg/kg p.o. daily) were administered for 28 days. Studies into the effect of alpha-escin on the development of steroid-induced osteopenia included the determination of an increase in body and adrenal glands mass in rats, determination of macrometrical parameters, of calcium and other minerals density in examined bones and determination of mechanical endurance of femoral bone. The carried-out experiments indicated that the p.o. administration of 100 mg/kg of alpha-escin for 28 days to sexually mature male rats with experimental steroid-induced osteopenia caused slight protective action on bone tissue against unfavourable influence of prednisolone manifested by enhancement of mechanical features of femoral bone.

Effects of alpha-escin on histomorphometrical parameters of long bones in rats with experimental post-steroid osteopenia.

The excess of glucocorticosteroids leads to the development of osteopenia. A decreased bone formation rate and an increased bone resorption rate are observed. The aim of the present study was to investigate the effects of alpha-escin on the experimental prednisolone-induced osteopenia. The experiments were carried out on male Wistar rats with initial body weight of 240-310 g, divided into 4 groups (n = 6): Control, Alpha-escin, Prednisolone, Prednisolone + alpha-escin. Prednisolone (5 mg/kg im daily) and/or alpha-escin (100 mg/kg po daily) were administered for 28 days. Transverse cross-section surfaces of the cortical diaphysis and of the marrow cavity in the tibia, transverse growth, width of endosteal and periosteal osteoid, thickness of trabeculae and width of epiphyseal cartilage were examined. Prednisolone administration caused osteopenic changes in rat bones. Alpha-escin administered to the control rats did not exert statistically significant influence on the investigated bone parameters. Alpha-escin administration to prednisolone-treated rats slightly reduced the unfavorable effects of prednisolone on width of periosteal and endosteal osteoid and periosteal transverse growth in the tibia.

Influence of alpha-escin on skeletal changes in ovariectomized rats.

The aim of the present study is to investigate the influence of alpha-escin (35 mg/kg per os daily; administered for 4 weeks) on the development of osteopenia caused by bilateral ovariectomy in 3-month-old female Wistar rats. The experiments were carried out on four groups of animals: I (C)--control sham operated rats, II (OVX)--ovariectomized rats, III (E)--sham operated rats which were administered alpha-escin, IV (OVX + E)--ovariectomized rats which were given alpha-escin. In all groups body weight growth, masses, length and tibia diameter were determined as well as histological specimens of right femur and tibia slices were used for histometric measurements including: the transverse cross-section area of the tibial shaft cortex, transverse cross-section area of the tibial marrow cavity, periosteal osteoid width, endosteal osteoid width, periosteal thickness growth in the tibia, endosteal thickness growth in the tibia, epiphyseal and metaphyseal trabeculae thickness in the femur and epiphyseal cartilage width. Bilateral ovariectomy in matured female rats caused osteopenic skeletal changes. alpha-Escin (35 mg/kg per os daily) administered to the ovariectomized rats for the following 28 days decreased only a little the development of osteopenic skeletal changes caused by bilateral ovariectomy.

Effect of dexamethasone on the lymphocytic Na+/H+ antiporter activity.

OBJECTIVE: The effects of short-term administration of dexamethasone on sodium/proton antiporter (Na+/H+ antiporter) in human lymphocytes were investigated in vitro. METHODS: Cytosolic pHi in lymphocytes was measured spectrophotometrically using the pH-sensitive fluorescent dye 2'-7'-bis-carboxyethyl-5(6)-carboxyfluorescein at 530 nm with excitation wavelengths of 440 and 530 nm. The Na+/H+ antiporter activity was determined after intracellular acidification using 100 mmol/l propionic acid. RESULTS: The addition of 1 micromol/l dexamethasone significantly reduced cytosolic pHi from 7.44+/-0.03 to 7.25+/-0.05 (mean +/- SEM; P<0.01). Incubation with dexamethasone for 40 min significantly reduced the Na+/ H+ antiporter activity from (9.19+/-0.61)x10(-3) pHi/s (n = 22) to (7.23+/-0.49)x10(-3) pHi/s (n = 22; P<0.01). The effect of dexamethasone was time and concentration dependent The apparent affinity of the Na+/H+ antiporter was not significantly different in the absence or presence of dexamethasone. The inhibition of the Na+/H+ antiporter by dexamethasone was abolished in the presence of the glucocorticoid receptor blocker, mifepristone. CONCLUSION: Dexamethasone directly inhibits the Na+/H+ antiporter using a receptor-dependent pathway. This effect may be important for pharmacological side effects such as glucocorticoid-induced hypertension.

Influence of alpha-escin on the femoral bone strength in ovariectomized rats.

The aim of the present study was to investigate the effect of alpha-escin (35 mg/kg po, daily) administered for 4 weeks on the femoral bone strength in 3-month-old ovariectomized Wistar rats. The experiments were carried out on four groups of animals: I (C)-control sham operated rats, II (OVX)-ovariectomized rats, III (E)-sham operated rats which were administered alpha-escin, IV (OVX+E)-ovariectomized rats which were administered alpha-escin. Bilateral ovariectomy caused osteopenic skeletal changes in mature female rats. alpha-Escin (35 mg/kg po, daily) administered to the ovariectomized rats for 28 days only to little extent decreased the development of osteopenic skeletal changes which were caused by bilateral ovariectomy. alpha-Escin (35 mg/kg po, daily) administered to the sham operated rats for 28 days caused slight changes in the skeletal system, which were characterized by the increase in the bone formation processes.

Synthesis of two new angiotensin II analogs.

The synthesis of two new angiotensin II analogs: [Des-Arg2, epsilon Ahx1]-angiotensin (II (1) and [Des-His0)-angiotensin (II (2) is reported. Rather strong agonist activity shows analog (1)-78% and weak-analog (2)-30% of the contractile activity of angiotensinamide. None of the synthesized peptides has antagonist activity.

The influence of psychotropic drugs on the phosphodiesterase activity in the rat brain meninges.

Phosphodiesterase (PDE) is present in brain meninges. Its activity is higher in the pia than in the dura mater. Phenothiazine neuroleptics: fluphenazine, trifluoroperazine, thioproperazine, chloropromazine and thioridazine at concentration 10(-5)--10(-4) M in vitro inhibit the PDE activity in the pia and dura mater. Most potent in this respect were fluphenazine and trifluoroperazine. Much less pronounced inhibition of PDE activity in brain meninges was found after in vitro administration of tricyclic antidepressant: nortriptyline, chlorimipramine, protriptyline, desipramine and imipramine in concentrations 10(-4)--10(-3) M. Administered in vivo in a dose of 0.1 mg or 5 mg/kg ip fluphenazine inhibited the hydrolysis of 32P-cAMP injected into subarachnoid space. The results indicate that PDE present in the rat brain meninges may control the cAMP level in the cerebrospinal fluid. Treatment with phenothiazine neuroleptics which inhibit the PDE activity in meninges may significantly depress the hydrolysis of cAMP in the cerebrospinal fluid.

Metabolism of cyclic 3',5'-AMP injected into the rat brain lateral ventricle.

(14C)-cAMP was injected into the lateral ventricle of the rat brain and autoradiographic studies and assay of metabolism of this nucleotide were carried out. (14C)-cAMP rapidly penetrates into the cerebrospinal fluid in other brain ventricles and into the subarachnoidol cerebellar space. 14C was also present in the brain tissue adjacent to the lumen of the ventricles. Given intraventricularly (14C)-cAMP is rapidly metabolized and the presence of 14C in the brain tissue is probably the consequence of the incorporation of metabolites of (14C)-cAMP.

The effect of agents stimulating dopaminergic system on incorporation of exogenous adenine into striate body slices of the rat.

We tested the effect of various concentrations (10(-6)--10(-4) M) of dopamine (DA), apomorphine (APM), amantadine (AMD), dimethylaminoadamantane (DMAD) and haloperidol (HP) on in vitro incorporation of 14C/U/adenine to slices of the rat striate body. Two mechanisms participated in this incorporation: one of them (uptake I) of Km = 1.92 micron, the second (uptake II) of Km 434 micron, APM inhibited both uptake I and II, while AMD and DMAD only the uptake I. HP at concentration inhibiting the dopaminergic receptors did not affect the inhibition by APM, AMD or DMAD of incorporation of exogenous adenine to striatal slices. Incorporation of exogenous adenine was not related to stimulation by specific (DA) or unspecific (APM, AMD, DMAD) stimulants of dopaminergic receptors in the rat striate body. The inhibition of the uptake produced by APM, AMD and DMAD may be related to the mechanism of action of these compounds.

The effect of drugs stimulating central dopaminergic system on transformation of exogenous adenine into c-AMP.

We tested the effect of dopamine (DA), apomorphine (APM), amantadine (AMD), dimethylaminoadamantane (DMAD) or haloperidol (HP) on the in vitro formation of c-AMP from ATP labelled intracellularly with exogenous 14C-adenine or from endogenous ATP in the slices of rat striatum. DA stimulated the synthesis of c-AMP from endogenous and 14C-adenine labelled ATP. Nonspecific stimulants of the dopaminergic system, APM, AMD and DMAD, stimulated the c-AMP synthesis much weaker than DA did. After application of APM, ADM or DMAD, the utilization of ATP formed from 14C/U/adenine for synthesis of c-AMP was lower than after DA. The effects of combined treatment with DA together with APM, AMD or DMAD was additive. HP, 1 X 10(-3) M did not change the amount of radioactive and total c-AMP, but inhibited the stimulatory action of DA and, to a lesser degree, of APM, AMD and DMAD. The synthesis of c-AMP from endogenous ATP stimulated with APM, AMD and DMAD in striate body slices was inhibited by HP more strongly than the synthesis of c-AMP from ATP labelled with exogenous 14C-adenine. The results indicate that ATP synthesized from intracellular adenyl nucleotides is more effectively utilized for the synthesis of c-AMP stimulated by APM, AMD or DMAD in striate body slices, than ATP labelled with 14C-adenine.