Effects of citalopram and fluoxetine on the corticocerebral blood flow in conscious rabbits

Depression, which is associated with an increased incidence of vascular events, frequently occurs following stroke. Selective serotonin reuptake inhibitory drugs (SSRIs) as antidepressants, are well tolerated, and also seem to be effective in post-stroke depression. The aim of this study was to investigate the effects of the SSRIs citalopram and fluoxetine, on the corticocerebral blood flow (cCBF) in rabbits with unilateral carotid occlusion induced cerebral ischemia. The cCBF was measured by the hydrogen clearance technique. After determination of the mean baseline cCBF, the effects of individual doses (0.1, 0.3 and I mg/kg) of citalopram or fluoxetine on the cCBF were investigated. Following the induction of an impaired cCBF, the changes in cCBF after drug treatments in this condition were likewise measured. The mean arterial blood pressure (MABP) and the heart rate (HR) from the electrocardiogram (ECG) were also determined. Neither citalopram nor fluoxetine influenced the cCBF in the control group. Fluoxetine improved the cCBF only very slightly in the ischemic animals. In contrast, all the doses of citalopram exerted pronounced and dose-dependent cCBF-increasing effects in the animals with unilateral carotid occlusion (maximal mean ACBF: 10, 16 and 27 ml/min/100 g tissue). The HR was decreased in both groups. Only citalopram treatment led to a slight MABP-decreasing effect. Besides enhancement of the serotonergic transmission in the brain, the cCBF-increasing effect of citalopram under ischemic conditions may be of benefit in post-stroke and vascular depression.

Prenatal and newborn paternity testing with DNA analysis

In rape against youthful girls which yields pregnancy after the abortion DNA examinations can be performed from the aborted foetal material to provide evidence of paternity of the suspect. In our present work we demonstrate six cases: four of them are rape cases and two where the mother abandoned her newborn baby. These cases proved that DNA-STR profiles can be determined from foetus after the abortion and perpetrator of a rape can be found. Due to our result we suggest that not only placenta but also bloody vernix caseosa is useful tissue for identifying the putative mother because vernix caseosa can be the carrier of the mother's blood.

Comparison of regional vasomotor responses to acetazolamide and CO2 in rabbit cerebrum and cerebellum, measured by a hydrogen clearance method

AIM

Many investigators have proved the usefulness of acetazolamide provocation and the carbon dioxide test for assessment of the local cerebrovascular reactivity by measurement of the regional cerebral blood flow in patients with occlusive cerebrovascular disease. Data originating from a comparison of these two different vasomotor stimuli as concerns the differences in sensitivity to them in various parts of the central nervous system are scarce. Our aim was to compare the cerebral blood flow responses to hypercapnic and acetazolamide stimuli in different brain regions.

METHODS

The cerebral blood flow was measured in the cerebrum (cortex and caudate nucleus) and cerebellum (cortex), as measured by a hydrogen clearance method in anaesthetized, artificially ventilated rabbits.

RESULTS

In normocapnia, the cerebral blood flow values in the cerebrum and the cerebellum differed significantly. The cerebral blood flow responses to both vasodilatory stimuli were to be significantly higher in the cerebrum than in the cerebellum, but the relative increases, i.e. the mean relative reactivities, were similar in the different regions measured.

CONCLUSION

The regional dissimilarity might explain to some extent the different sensitivities of the various brain areas to sudden blood pressure changes (infarction or haemorrhage). The results further suggest that heterogeneity in cerebrovascular reactivity should be considered in the assessment of vasoreactivity in patients with occlusive cerebrovascular disease. Since the comparison of the carbon dioxide and acetazolamide-induced cerebrovascular reactivities revealed a strong linear relationship, it was concluded that acetazolamide provocation is equivalent to the carbon dioxide test in the evaluation of cerebrovascular reactivity.

Influence of nitrovasodilators and cyclooxygenase inhibitors on cerebral vasoreactivity in conscious rabbits

Since the nitric oxide (NO) and cyclooxygenase pathways have been suggested to have important roles in most vasodilations, our aim was to study the influence of cyclooxygenase inhibitors and nitrovasodilators on cerebrovascular reserve capacity. Corticocerebral blood flow was measured by hydrogen polarography during hypercapnia and acetazolamide stimuli in conscious rabbits. The measurements were repeated in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME) and indomethacin as nitric oxide synthase (NOS) and cyclooxygenase inhibitors. The effects of nitroglycerin and isosorbide-5-nitrate were also tested. L-NAME completely, while indomethacin markedly inhibited the hypercapnic corticocerebral blood flow response. Nitroglycerin and isosorbide-5-nitrate significantly attenuated hypercapnia elicited corticocerebral blood flow increase. The different treatments reduced only moderately the acetazolamide-induced corticocerebral blood flow response. These results lend support to the hypothesis that antithrombotic and antiinflammatory medication (cyclooxygenase inhibitors) and nitrovasodilator treatments could interfere with the measurement of cerebrovascular reactivity resulting in underestimation of the cerebrovascular reserve capacity in patients taking these drugs.

Effects of moxonidine on corticocerebral blood flow under normal and ischemic conditions in conscious rabbits

Hypertension associated with excessive liberation of circulating and tissue catecholamines is an independent risk factor for further cardiovascular complications and an important predictor of stroke. Moxonidine is a centrally acting anti-hypertensive drug with potent action on I1-imidazoline receptors. It inhibits catecholamine release and is therefore expected to exert an antiadrenergic effect at various levels in the regulation of the cardiovascular system. The aim of this study was to investigate the effect of moxonidine (0.025-0.1 mg/kg, i.v.) on the normal and unilateral carotid occlusion-induced impaired corticocerebral blood flow (cCBF) determined by hydrogen polarography, on mean arterial blood pressure (MABP) and heart rate (HR) in conscious rabbits. Moxonidine produced a reduction of MABP and HR. On the other hand, after administration of the drug, a significant increase in the normal and impaired cCBF was observed. Because the improvement in cCBF was conspicuous in both normal and ischemic conditions, moxonidine might be beneficial not only in the treatment of hypertension but also in the management of cerebral ischemia.

The Y-STRs DYS19 and DYS390 in a south-east Hungarian (Szeged area) population

The allele frequencies of DYS19 and DYS390 located on the Y chromosomes were determined from male bloodstain samples of 308 (DYS19) and 268 (DYS390) unrelated male adults in south-east Hungary. Six alleles could be distinguished in both systems, yielding 22 DYS19/DYS390 halotypes in a subset of 239 males.

The STR systems HumVWA and HumACTBP2 in a Hungarian population

Allele frequencies of the Short tandem repeat systems HumVWA and HumACTBP2 were determined from 105 unrelated individuals from the area of Szeged, Hungary. A total of 8 alleles was detected for VWA, and 23 alleles were found for ACTBP2. In both systems no deviations from Hardy-Weinberg equilibrium were observed. A comparison of the Hungarian and German frequency profiles revealed significant differences at both STR loci.

Measurements of regional cerebral blood flow and blood flow velocity in experimental intracranial hypertension: infusion via the cisterna magna in rabbits

Cerebral blood flow velocity, as measured in the intracranial segment of the internal carotid artery by transcranial Doppler sonography via the transorbital route, and regional cerebral blood flow and volume in corresponding cortical areas, as measured by the hydrogen clearance technique, were recorded for eight New Zealand White rabbits subjected to infusion via the cisterna magna to elevate intracranial pressure. In the lower range of autoregulation, that is, at perfusion pressures between 80 and 40 mm Hg and even lower, the changes in cerebral blood flow velocity and cerebral blood flow showed a strong correlation (0.86) under conditions of standard pCO2 (PaCO2 = 35 +/- 2 mm Hg). Autoregulation was exhausted at 40 mm Hg, and the cerebrovascular resistance was minimal. Below this perfusion pressure, the cerebral blood flow and volume dropped sharply, whereas the cerebrovascular resistance gradually increased, indicating that, despite the maximally dilated resistance vessels, intracranial hypertension causes vascular resistance to increase, possibly via blocking of the venous outflow. Our results confirmed that noninvasive and easily (even at bedside) applicable measurements of changes in cerebral blood flow velocity could be a substitute for the cumbersome and expensive isotope measurements of cerebral blood flow in patients with intracranial hypertension.

Disturbance of motoric function as behavioral measure of impaired cerebral circulation in mice

Aim of the present experiments was to elaborate an experimental model exhibiting the functional consequences of a moderate impairment of cerebral circulation sensitive enough for testing the long-term cerebroprotective effect of different drugs. In preliminary experiments mice survived unilateral occlusion of the carotid artery. This intervention, however, severely impaired the motor skill of the animals as measured by their activity on the rotating treadmill. Motimeter activity was also diminished following unilateral carotid occlusion. Somewhat unexpectedly, a more complex pattern of learned behavior in a one-trial learning passive avoidance paradigm was only modestly affected by unilateral carotid occlusion. Papaverine (2.0 mg/kg) normalized the motor incoordination measured on the rotating treadmill. The data suggest that impaired motoric function, as a result of unilateral carotid occlusion, might be a useful experimental tool to analyse functional consequences of impaired cerebral circulation and a sensitive test for screening of drugs with presumed cerebroprotective action.

Chronotropic effect of histamine on cultured neonatal rat heart cells

The positive chronotropic effect (PCE) of histamine in cultured neonatal rat heart cells was monitored using a microscopic method as well as an electro-optically recording device. The action potential frequency was also measured (by means of microelectrodes). An increase in PCE was noted when histamine (from 1 X 10(-6) M to 1 X 10(-5) M) was added to the cells. However, higher concentrations (from 1 X 10(-5) M to 1 X 10(-4) M) were less effective. The PCE of histamine was reduced by pretreating the cells with antihistaminic drugs. H1-blocking agents (promethazine and mepyramine) were more potent than H2-blocking drugs (metiamide and cimetidine). In addition, the PCE of histamine was abolished when the cells were in presence of high K+ medium (26 mEq) but contraction and action potential amplitudes were increased. Our results demonstrate that these cultures respond to histamine and that this response is abolished by antihistaminic drugs thus suggesting the H1 and/or H2 receptors may be present in the neonatal rat heart cell cultures.

Possible mode of action of nitroglycerin on heart mitochondria

Nitroglycerin has no effect on the electron transport and oxidative phosphorylation of isolated rabbit heart mitochondria at 5 X 10(-4) M and lower concentrations. However, it diminished the phosphate-induced energy-dependent potassium fluxes through the mitochondrial membrane in both directions; thus it was able to prevent the impairment of the efficiency of oxidative phosphorylation produced by increased ion transport.