Role of 5HT in the morbidity of cerebral infarction-a study in the gerbil stroke model

Comparison of the effects of bifemelane hydrochloride, idebenone and indeloxazine hydrochloride on ischemia-induced changes in brain monoamines and their metabolites in gerbils

Bifemelane hydrochloride (bifemelane), idebenone and indeloxazine hydrochloride (indeloxazine) are used clinically to reduce apathy and other emotional disturbances in patients with cerebrovascular disease. In gerbil brains, ischemia affects many monoaminergic neurotransmitters and their metabolites. In the present study, the effects of treatment with bifemelane, idebenone and indeloxazine on ischemia-induced changes in monoamines and their metabolites were studied in ischemic gerbil brains. Although these drugs had no effect on the monoaminergic neurotransmitters or their metabolites in sham-operated animals, in the ischemic brains both dopamine and serotonin turnovers were abnormal after idebenone or indeloxazine treatment. Bifemelane, in contrast, tended to correct the ischemia-induced changes in the dopaminergic and serotonergic systems in the cerebral cortex, hippocampus and thalamus + midbrain. From the present results and those in previous reports, we conclude that bifemelane is more appropriate than idebenone or indeloxazine as a treatment for the ischemia-induced changes in monoaminergic neurotransmitter systems.

The effects of sho-saiko-to-go-keishi-ka-shakuyaku-to (TJ-960) on ischemia-induced changes of brain acetylcholine and monoamine levels in gerbils

The changes in acetylcholine (ACh), monoamine and monoamine metabolite levels following cerebral ischemia in Mongolian gerbils were examined. In addition, the effects of Sho-saiko-to-go-keishi-ka-shakuyaku-to (TJ-960), which is a spray-dried mixture of 9 herbal drugs, on these changes were also examined. The dramatic decrement of ACh levels in ischemic gerbils was significantly inhibited by p.o. administration of TJ-960 at a daily dose of 3.5 g/kg or 700 mg/kg for one month. Norepinephrine (NE) was also reduced in all ischemic brain regions, and TJ-960 also recovered the level of NE. In ischemic gerbil brains, the dopamine (DA) levels decreased and its metabolites increased in the striatum, but DA and its metabolites in the thalamus + midbrain region increased. The serotonin (5HT) level was reduced in the cerebral cortex and hippocampus. TJ-960 inhibited these monoaminergic changes in ischemic gerbils. This suggests that TJ-960 may provide anti-ischemic action and beneficial effects on various symptoms induced by ischemia.

The effects of acute cerebrovascular disease on serum and cerebrospinal fluid parameters

In order to evaluate the effects due to acute cerebrovascular disease on serum and cerebrospinal fluid (CSF) parameters, biochemical data from 312 patients were studied. In serum, CK, LD and alpha 1 protein fraction showed a moderately close relationship to the severity of stroke. In CSF there could not be observed any relation between enzymatic activities (LD, ASAT, CK) and the severity of the disease. The same result was found for CSF protein and the ratio CSF albumin/serum albumin, parameters which are indicative for Blood Brain Barrier (BBB) disturbances. Substances from the intermediate metabolism in the Central Nervous System (CNS) (lactate and pyruvate) were evidently raised in CSF and there was a clear relation between the CSF concentration and the severity of stroke. No indication for IgG immunoglobulin abnormalities in CSF was found. The concentration of neurotransmitter metabolite 5HIAA in CSF was significantly higher in (in)completed stroke than in Transient Ischaemic Attack.

Common carotid artery stump pressure in the gerbil stroke model

In 106 slightly anaesthetised adult mongolian gerbils one common carotid artery (CCA) was ligated and the blood pressure in the distal and in the proximal stump was monitored for 8 minutes. The mean distal CCA stump pressure of the 39 nonsurvivors was 15 (+/- 6) mm Hg, that of the 25 survivors with retinocerebral infarcts was 25 (+/- 6) mm Hg, and that of the 42 intact survivors was 31 (+/- 7) mm Hg. The corresponding mean arterial blood pressures (MABP), as measured in the proximal CCA stump, were 81 (+/- 12) mm Hg, 84 (+/- 13) mm Hg, and 87 (+/- 11) mm Hg, respectively. There were no differences between the samples concerning sex, body weight, rectal temperature, arterial blood gases, arterial pH, and haematocrit. Measurements in a second series of 10 awake gerbils showed that the mean values of MABP, heart rate, and respiratory rate of the nonsurvivors were less than those of the survivors during 90 minutes after CCA ligation. It is inferred that in the mongolian gerbil the lower threshold of the arterial blood pressure for the development of brain infarcts ranges within 22 and 25 mm Hg, that is, within the values found in monkeys and cats. The longlasting depression of respiration and circulation in the nonsurvivors is considered to be related to the phenomenon of diaschisis .

Changes in cortical and subcortical levels of monoamines and their metabolites following unilateral ventrolateral cortical lesions in the rat

Suction lesions were made in the anterior, posterior or both halves of the right ventrolateral cortex in rats. Six days later, levels of the monoamine neurotransmitters, norepinephrine (NE), dopamine (DA) and serotonin (5-HT), and their metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA), were measured in cortical and subcortical regions of lesioned rats and compared to values in sham-operated animals. NE and 5-HT were decreased in sections of ipsilateral (right) cortex including, and posterior to lesions, while 5-HIAA was increased throughout the ipsilateral cortex. Decreases in monoamines and increases in metabolites and metabolite:monoamine ratios (especially 5-HIAA:5-HT) were found in ipsilateral subcortical structures, including striatum, nucleus accumbens, hippocampus, hypothalamus, midbrain and brainstem, depending on the type of lesion. Subacutely, focal ventrolateral cortical lesions may profoundly alter the levels and utilization rates of monoamine neurotransmitters in widespread regions of the ipsilateral hemisphere.

The effect of ischemia on biogenic amine concentrations in the central nervous system

A rabbit spinal cord ischemia model was used to study the effects of focal ischemia on the tissue concentrations of serotonin, 5-hydroxyindole acetic acid, and norepinephrine. Ischemia induced by abdominal aorta occlusion caused both serotonin and norepinephrine concentrations to decline in the most ischemic areas of the spinal cord by 55 minutes. In marginally perfused adjacent areas, serotonin concentrations transiently declined at 14 and 20 min. After the onset of ischemia and then returned to normal. The minimum was reached at the same time when previous studies showed damage had become irreversible in more ischemic regions. Concentrations of 5-hydroxyindole acetic acid did not change at any time and norepinephrine declined only in the most ischemic areas after damage was irreversible. Thus, permanent serotonin and norepinephrine decreases occur only in areas destined to be destroyed by infarction, but the serotonin returns to normal in marginal tissue that remains viable. These studies suggest that serotonin may be involved in the early stages of irreversible changes during central nervous system ischemia.