EVALUATION OF THE ACTION OF VINPOCETINE ON SOME MONOAMINES IN TRANSIENT ISCHEMIC ATTACKS: AN EXPERIMENTAL AND CLINICAL STUDY
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Vinpocetine (VP) is a selective inhibitor of Ca++ calmodulin-dependent cGMP phosphodiesterase (PDE). It is assumed that this inhibition enhances intracellular cGMP levels in vascular smooth muscles leading to reduced resistance of cerebral blood. This in turn, will lead to neuroprotection in transient ischemic attacks (TIAs). The aim of the present study was to investigate the effect of VP on some peripheral menoamines in human namely, serum norepinephrine (NE) and blood serotonin (5HT). Moreover, cortical NE, 5-HT and dopamine (DA) were investigated in the cortex of brain rat subjected to experimental transient ischemia induced by carotid artery occlusion. Regarding the clinical part, it was carried out on forty (40) individuals. Ten (10) of them were volunteers, above 40 years old, both sexes and of good health as controls. The other thirty (30) were outpatients from Benha university hospitals, both sexes (22 males and 8 females), aged from 40- 60 years (mean 51+1.1) and were suffering from TLAs. They entered the study according to definite inclusive and exclusive criteria, and divided into 2 groups each of them was 15 patients. The first group did not take medications (Non-Vinpocetine Treated Group), and the other group treated with VP (5mg td.$) for 2 months. Results of this part revealed signfficant elevation (P<0.05) of peripheral serum NE and blood 5 HT in Tills nontreated patients compared to the control group, and this level is main- tamed elevated significantly in VP treated patients compared to control group, however, this elevation was not significant compared to TIAs nontreated group (P<0.05). In the experimental part of ow- work, we used 126 albino rats, both sexes, weighing from 150-200 gms and divided into three groups (I), (11) and (III) each group consisted of 42 rats. Six rats from each group were served for determination of cerebral (schemia using triphenyl tetrazoliurn chloride (T.T.C) (subgroup. d). The other 36 rats in each group were subdivided into 3 sub-groups (a), (19) and (c) each consisted of 12 rats, and were used for determination of cortical NE, 5HT and DA respectively. Group (1) did not receive any medication and served as control group. Group (II) subjected to transient ischemia by occlusion of carotid arteries. Group (III) treated with VP (5 pg/kg/B.W., 1.P.) ten minutes before induction of ischemia. Results of this part revealed significant elevation of NE 5I11' and DA in the cortex of ischemic rats Group (II) compared to control group (I) (P<0.05) and the level of 511T is maintained elevated significantly in group (117) compared to control group (I) or ischemic non-treated group (II) while the level of DA and NE were reduced significantly (P<0.05) In group (III) treated with VP before ischemia compared t9 group (1) or group In conclusion, the protective effect of VP in TIAs may have an adding mechanism attributed to maintaining elevated level of serum NE, blood 5 HT and also due to reduced level of cortical DA and NE and maintained elevated level of 5PIT.