Supplementation with vitamins E plus C or soy isoflavones in ovariectomized rats: effect on the activities of Na<Superscript>+</Superscript>, K<Superscript>+</Superscript>-ATPase and cholinesterases

Since a previous study demonstrated that ovariectomized rats present an activation of Na⁺, K⁺-ATPase and acetylcholinesterase (AChE) activities, in the present study we investigated the influence of vitamins E plus C or soy isoflavones on the effects elicited by ovariectomy on the activities of these enzyme in hippocampus of ovariectomized rats. We also determined the effect of the same compounds on the reduction of serum butyrylcholinesterase (BuChE) activity caused by ovariectomy. Female adult Wistar rats were assigned to one of the following groups: sham (submitted to surgery without removal of the ovaries) and ovariectomized. Seven days after surgery, animals were treated for 30 days with a single daily intraperitoneous injection of vitamins E (40 mg/kg) plus C (100 mg/kg) or saline (control). In another set of experiments, the rats were fed for 30 days on a special diet with soy protein or a standard diet with casein (control). Rats were sacrificed after treatments and the hippocampus was dissected and serum was separated. Data demonstrate that vitamins E plus C reversed the activation of Na⁺, K⁺-ATPase and AChE in hippocampus of ovariectomized rats. Conversely, soy protein supplementation reversed the increase of AChE activity, but not of Na⁺, K⁺-ATPase activity, caused by ovariectomized group. Neither treatment was able to reverse the reduction of serum BuChE activity. Furthermore, treatments with vitamins E plus C or soy were unable to reverse the decrease in estradiol levels caused by ovariectomy. Our findings show that the treatment with vitamins E plus C significantly reversed the effect of ovariectomy on hippocampal Na⁺, K⁺-ATPase and AChE activities. However, a soy diet that was rich in isoflavones was able to reverse just the increase of AChE. Neither treatment altered the reduction in serum BuChE activity. Taken together, these vitamins and soy may have a protective role against the possible brain dysfunction observed in some menopause women. Vitamins E plus C and soy isoflavones may be a good alternative as a novel therapeutic strategy.     

Ovariectomy increases Na+, K+-ATPase, acetylcholinesterase and catalase in rat hippocampus

In the present work we investigated the effect of ovariectomy on Na+, K+-ATPase and acetylcholinesterase (AChE) activities in rat hippocampus. We also studied some parameters of oxidative stress, namely total radical-trapping antioxidant potential (TRAP), thiobarbituric acid-reactive substances (TBA-RS), as well as the antioxidant enzyme activities superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities. Our hypothesis is that ovariectomy might cause alterations in essential enzyme activities necessary to brain normal functioning and that these chances could be caused by oxidative stress. Female adult Wistar rats were divided into three groups: (1) naive (control); (2) sham-operated; and (3) ovariectomized. Thirty days after ovariectomy rats were sacrificed. Results showed that rats subjected to ovariectomy presented a significant increase in Na+, K+-ATPase, AChE and CAT activities, but did not change the oxidative stress parameters studied when compared to sham or naive rats. Since ovariectomy mimics postmenopausal changes, our findings showing alteration in the activities of brain Na+, K+-ATPase, AChE and CAT may be related to problems in postmenopausal women.     

Ganglioside Alterations in the Central Nervous System of Rats Chronically Injected with Methylmalonic and Propionic Acids

Neurological dysfunction and structural cerebral abnormalities are commonly found in patients with methylmalonic and propionic acidemia. However, the mechanisms underlying the neuropathology of these disorders are poorly understood. We have previously demonstrated that methylmalonic and propionic acids induce a significant reduction of ganglioside N-acetylneuraminic acid in the brain of rats subjected to chronic administration of these metabolites. In the present study, we investigated the in vivo effects of chronic administration of methylmalonic (MMA) and propionic (PA) acids (from the 6th to the 28th day of life) on the distribution and composition of gangliosides in the cerebellum and cerebral cortex of rats. Control rats were treated with the same volumes of saline. It was first verified that MMA and PA treatment did not modify body, cerebellum, or cortical weight, nor the ganglioside concentration in the cerebral cortex of the animals. In contrast, a significant reduction in total ganglioside content in the cerebellum of approximately 20–30% and 50% of control levels occurred in rats injected with MMA and PA, respectively. Moreover, chronic MMA and PA administration did not interfere with the ganglioside pattern in the cerebral cortex, whereas the distribution of individual gangliosides was altered in the cerebellum of MMA- and PA-treated animals. Rats injected with MMA demonstrated a marked decrease in GM1 and GD3, whereas chronic PA treatment provoked a significant reduction of all ganglioside species, with the exception of an increase in GM2. Since gangliosides are closely related to the dendritic surface and other neural membranes, indirectly reflecting synaptogenesis, these ganglioside abnormalities may be associated with the brain damage found in methylmalonic and propionic acidemias.     

Reduction of Butyrylcholinesterase Activity in Rat Serum Subjected to Hyperhomocysteinemia

In the present study we investigate the effect of homocysteine (Hcy) administration, the main metabolite accumulating in homocystinuria, on butyrylcholinesterase (BuChE) activity in serum of rats. For the acute treatment, 29-day-old Wistar rats received one subcutaneous injection of Hcy (0.6 mol/g) or saline (control) and were killed 1 h later. For the chronic treatment, Hcy was administered subcutaneously to rats from the 6th to the 28th day of life. Control rats received saline. The rats were killed 12 h after the last injection. In another set of experiments, rats were pretreated for one week with vitamins E and C or saline and 12 h after the last injection received one single injection of Hcy or saline, being killed 1 h later. Serum was used to determine BuChE activity. Our results showed that acute and chronic administration of Hcy significantly decreased BuChE activity. Furthermore, vitamins E and C per se did not alter BuChE activity, but prevented the reduction of this enzyme activity caused by acute administration of Hcy. The data suggest that the inhibitory effect of Hcy on BuChE activity is probably mediated by free radicals, since vitamins E and C administration prevented such effect.     

Proline Reduces Acetylcholinesterase Activity in Cerebral Cortex of Rats

In the present study we investigated the in vivo and in vitro effect of proline (Pro) on acetylcholinesterase (AChE) activity in rat cerebral cortex. The action of vitamins E and C on the effects produced by Pro was also tested. Twelve-day-old rats received one s.c. injection of Pro (12.8 mol/g body weight) or an equivalent volume of 0.9% saline solution (control) and were killed 1 h later. In another set of experiments, 5-day-old rats were pretreated for 1 week with daily i.p. administration of saline (control) or vitamins E (40 mg/kg) and C (100 mg/kg). Twelve hours after the last injection the rats received one s.c. injection of Pro (12.8 mol/g body weight) or saline (control) and were killed 1 h later. For the in vitro studies, cerebral cortex homogenates of 12-day-old untreated rats were incubated for 1 h with various concentrations of Pro (3.0 M–1.0 mM) or with 1.0 mM Pro, 1.0 mM trolox, or 1.0 mM Pro plus 1.0 mM trolox. Controls did not contain Pro in the incubation medium. Our results showed that the AChE activity significantly decreased (25%) in rat brain subjected to Pro administration and that the pretreatment with vitamins E and C prevented this effect. Furthermore, Pro (0.5 and 1.0 mM) also inhibits AChE activity in vitro and trolox prevented this effect. The data suggest that the inhibitory effect of Pro on AChE activity is associated with oxidative stress. Although it is difficult to extrapolate our findings to the human condition, our results may be relevant to explain, at least in part, the neurologic dysfunction associated with hyperprolinemia type II.     

Highly selective inhibition of butyrylcholinesterase by a novel melatonin–tacrine heterodimers

Novel inhibitors of cholinesterases, especially butyrylcholinesterase (BuChE), were obtained by coupling melatonin–tacrine heterodimers via the carbamate bond. Compounds 14a‐i possessed potent cholinesterase inhibitory activity (with IC₅₀ values as low as 1.18 nm for acetylcholinesterase (AChE) and 0.24 nm for butyrylcholinesterase (BuChE)). These heterodimers exhibit selectivity toward BuChE, being from 4‐ to 256‐fold more active toward BuChE than AChE, but still acting as better AChE inhibitors than tacrine 4 .     

Melatonin increases oestradiol-induced bone formation in ovariectomized rats

To assess the effect of melatonin on bone metabolism in ovariectomized rats, receiving oestradiol therapy or not, melatonin was administered in the drinking water (25 microg/mL water) and oestradiol (10 microg/kg body weight) or vehicle was given subcutaneously 5 days/week for up to 60 days after surgery. Urinary deoxypyridinoline (a marker of bone resorption) and circulating levels of bone alkaline phosphatase activity (a marker of bone formation), as well as serum calcium and phosphorus levels, were measured every 15 days. Bone area (BA), bone mineral content (BMC), bone mineral density (BMD) and total body fat (expressed as 100 g body weight) were measured by dual-energy X-ray absorptiometry at the end of the experiment. Body weight and total body fat were augmented after ovariectomy, and decreased after melatonin or oestradiol treatment. The effect of melatonin on body weight was seen in sham-operated rats only. Ovariectomy augmented, and melatonin or oestradiol lowered, urinary deoxypyridinoline excretion. This effect of melatonin and oestradiol was seen mainly in ovariectomized rats. The efficacy of oestradiol to counteract ovariectomy-induced bone resorption was increased by melatonin. Melatonin or oestradiol lowered serum bone alkaline phosphatase activity. Melatonin inhibition was seen mainly on the increase of bone alkaline phosphatase activity that followed ovariectomy. Serum phosphorus levels decreased after melatonin administration and were augmented after oestradiol injection; overall, melatonin impaired the increase of serum phosphorus caused by oestradiol. Ovariectomy decreased, and oestradiol increased, serum calcium levels while melatonin augmented serum calcium in sham-operated rats only. On day 60 after surgery, BMD and content decreased after ovariectomy and were increased after oestradiol injection. Melatonin augmented BA of spine and BMC of whole of the skeleton and tibia. The highest values observed were those of rats treated concurrently with oestradiol and melatonin. The present results indicate that: (i) melatonin treatment restrained bone remodelling after ovariectomy; (ii) the effect of melatonin required adequate concentrations of oestradiol; (iii) melatonin augmented oestradiol effects on bone in ovariectomized rats; (iv) a counter-regulation by melatonin of the increase in body fat caused by ovariectomy was uncovered. The melatonin doses employed were pharmacological in terms of circulating melatonin levels but not necessarily for some other fluids or tissues.     

Pre- and postsynaptic markers of cholinergic neurons in the cerebral cortex of rats of different ages

In order to investigate the effect of aging on postsynaptic muscarinic binding, we measured 3H-PZ binding in the cerebral cortex of male Fisher 344 rats of different ages. ChAT activity was measured as a presynaptic marker of the cholinergic system. Total and salt-soluble AChE activities were also measured. Maximal binding of 3H-PZ and ChAT activity did not change during aging. The ratio of detergent-soluble AChE to salt-soluble AChE was lower in 30-month-old rats than in 4-month-old rats. The results of the present study do not indicate that the amount of M1 muscarinic receptors proposed to be located postsynaptically decreases during aging. In senescent rats, however, the proportions of salt-soluble and detergent-soluble AChE may differ form those in young rats.     

Mechanisms for altered reproductive function in female rats following neonatal administration of raloxifene

OBJECTIVE: Raloxifene is a non-steroidal selective estrogen receptor modulator (SERM) that mimics estrogenic activity on bone density and blood lipid concentration without uterotropic actions. Previous data from our laboratory indicated that, as is the case for estrogen, neonatal administration of raloxifene disturbed normal differentiation of the hypothalamic circuitries governing the gonadotropic axis. In contrast, raloxifene did not act in the same way as estrogen does on the neuronal systems controlling sexual receptivity in the female rat. At present, however, the mechanisms for these organizing effects of raloxifene are not completely elucidated. DESIGN AND METHODS: To analyze this phenomenon, female rats were injected daily with raloxifene (50, 100, 250 or 500 microg/rat per day) between days 1 and 5 of age. On day 23, hypothalamic gonadotropin-releasing hormone (LHRH) mRNA expression was assessed, and pituitary and plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured in basal and LHRH-stimulated conditions. In addition, LH and FSH responses to ovariectomy were evaluated in raloxifene-treated females. Finally, we monitored the ability of neonatal administration of a potent LHRH agonist ([d-Ala(6),d-Gly(10)]-LHRH ethylamide; 0.01 microg/kg per 12 h on days 1-5) to counteract the effects of raloxifene. RESULTS: Our analyses demonstrated that prepubertal rats (23-day-old females) treated neonatally with raloxifene showed decreased hypothalamic LHRH mRNA expression levels, reduced pituitary content of LH and FSH, reduced basal and LHRH-stimulated LH secretion in vivo and in vitro, and decreased response to ovariectomy. In addition, adult females treated neonatally with raloxifene showed anovulation and reduced serum LH levels; these effects were not prevented by the simultaneous administration of a LHRH agonist. CONCLUSION: In conclusion, our data demonstrate that neonatal administration of raloxifene can disrupt the programming of hypothalamic-pituitary-ovarian axis function. Reduced LH secretion, under basal and LHRH-stimulated conditions and after ovariectomy, is probably related to decreased LHRH expression, reduced pituitary LH content and/or decreased pituitary responsiveness to hypothalamic LHRH.     

Acetylcholinesterase activity in the brain of alloxan diabetic albino rats: Presence of an inhibitor of this enzyme activity in the cerebral extract

Background and Aim:

Ischemic manifestations and cerebral dysfunction have been demonstrated in diabetes. However, the pathogenesis of diabetes-induced cerebral dysfunction still remains to be elucidated. Hence, the present study was initiated.

Materials and Methods:

Type-2 diabetes was induced in albino rats (280–300g) with alloxan monohydrate (40 mg/Kg i.v.,) and the cerebrum, cerebellum and medulla oblongata of the brain were used 48 h after alloxan injection for modulations in acetylcholinesterase (AChE, EC 3.1.1.7) activity.

Results:

AChE activity in the discrete regions of the brain of rats decreased significantly (P<0.01, 0.05 and 0.05 respectively) in diabetes. In vitro studies using cerebral extract from alloxan diabetic rats demonstrated significant (P<0.05) inhibition of AChE activity in the brain of normal animals. Feeding with Cichorium intybus (chicory) leaf extract (500 mg/Kg) for 10 days resulted in an increase in AChE activity.

Conclusion:

The impairment in the glycemic control is the basic mechanism causing inhibition of neuronal activity. Cerebral extract from alloxan diabetic rats significantly inhibited the brain AChE activity of normal animals, indicating the presence of an inhibiting factor in the cerebrum of diabetic rats. Cichorium intybus when fed for 10 days offered neuroprotection by stimulating AChE activity.     

Homocysteine Inhibits Butyrylcholinesterase Activity in Rat Serum

In the present work we investigated the in vitro effects of homocysteine (Hcy) and methionine (Met), metabolites accumulated in homocystinuria, on butyrylcholinesterase (BuChE) activity in rat serum. We also studied the kinetics of the inhibition of BuChE activity caused by Hcy. For determination of BuChE we used serum of 60-day-old Wistar rats, which was incubated in the absence (control) or presence of Hcy (0.01–0.5 mM) or Met (0.2–2.0 mM). The kinetics of the interaction of Hcy and BuChE was determined using the Lineweaver–Burk double reciprocal plot. Results showed that serum BuChE activity was not altered by Met, but it was significantly inhibited (37%) by 500 M Hcy, a concentration similar to those found in blood of homocystinuric patients. The apparent K _m values, in the absence and presence of 500 M of Hcy, were 0.034 and 0.142 mM, respectively, and V _max of BuChE for acetylcholine (ACh) as substrate was 1.25 mol ACSCh/h/mg of protein. The K _i value obtained was 120 M, and the inhibition was of the competitive type, suggesting a common binding site for Hcy and ACh. It is proposed that inhibition of cholinesterase activity may be one of the mechanisms involved in the neurological dysfunction observed in homocystinuria.     

Sexual and developmental differences in peptides regulating growth hormone secretion in the rat

Sex differences in the hypothalamic control of growth hormone (GH) secretion were investigated by measuring rat GH-releasing factor (rGRF) and somatostatin in male and female rats. Rat GRF-like immunoreactivity (rGRF-IR) was higher in the median eminence and hypothalamic tissue outside of the median eminence of adult (90-day-old) male compared to female rats. A similar pattern of rGRF-IR content was found in the median eminence of 35-day-old rats. This sex difference developed between days 25 and 35 of age, during which time serum concentrations of insulin-like growth factor (IGF-1) and body weight increased in both sexes. To a lesser extent, the content of somatostatin-like immunoreactivity (SLI) was higher in the median eminence of adult female rats compared to male rats. Whole hypothalamic rGRF-IR and SLI contents were influenced only moderately by adult gonadectomy or gonadal steroid treatments. For example, estrogen increased rGRF-IR content in castrated rats, but orchidectomy alone or orchidectomy followed by testosterone did not influence rGRF-IR content. Additionally, whole hypothalamic SLI content was unaffected by orchidectomy or orchidectomy followed by testosterone or estrogen. One month after ovariectomy, rGRF-IR and SLI in whole hypothalamic fragments were similar to their respective contents in gonad-intact males. However, ovariectomy followed by estrogen or testosterone did not restore rGRF-IR content and partially restored SLI content to levels seen in gonad-intact females.     

Age-related responses of the rat cerebral cortex: influence of vitamin E and exercise on the cholinergic system

In this study, we have assessed the impact of vitamin E and exercise on acquisition and retention of spatial memory for a given task in aging rats, using a T-maze. Acetylcholine esterase (AChE) and cholineacetyl transferase (ChAT) activities and acetylcholine (ACh) were measured in the cerebral cortex (CC) of male Wistar rats of 4- (adult), 12- (middle-aged) and 18-months (old) of age. Animals were categorized into sedentary [(SEC (N)], sedentary supplemented [SEC (+E)], swim trained [SWT (N)] and swim trained supplemented [SWT (+E)]. In the old, ChAT activity increased in the SEC (+E). AChE activity was highest in the adults, irrespective of training or supplementation. By contrast, ACh concentration remained unaltered with age, exercise and supplementation. Middle-aged and old rats were benefited in terms of a better acquisition and retention in the case of those that were trained and supplemented with Vitamin E. Adults showed better retention in all the groups after 7 and 15 days, while in the middle-aged, training was beneficial after 15 days. We observed decreased AChE activity when old rats were trained with the supplement. Our results also suggest that this regimen may be analogous to the AChE inhibitors that are widely advocated to derive positive benefits in up-regulating the possible reduction in ACh and in turn age-associated memory deficits.     

Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

Iodothyronine deiodinase activities are regulated by sex steroids; however, the mechanisms underlying the reported sexual dimorphism are poorly defined. In the present report, we aimed to investigate whether type 1 deiodinase (D1) sexual dimorphism exists early in sexual development by studying pre-pubertal male (Pm) and female (Pf) rats, as well as adult controls (C) and gonadectomized male and females rats. Adult male Wistar rats were studied 21 days after orchiectomy (Tex), and adult females were studied 21 days after ovariectomy (Ovx), and after estradiol benzoate (Eb) replacement. Serum total triiodothyronine (T3) was higher in pre-pubertal (P) rats than in the matching adults, with no difference between genders, although in adult males T3 was significantly lower than in females. There were no sex or age differences in serum total T4. Serum TSH in pre-pubertal (P) rats was within the adult female range, and both were significantly lower than in adult males. D1 activity in liver was greater in Pm than in Pf. In adult females, liver D1 activity was lower, while in adult males it was higher than in P rats. The same pattern of D1 activity was found in kidney. In thyroid and pituitary, D1 activity was similar in Pm, Pf, and adult females, which were all significantly lower than in the adult male. There were no differences in serum T3 and T4 between C and Tex males, but serum TSH was significantly decreased in Tex rats. Hepatic and renal D1 activities were lower in Tex than in C, but no changes were detected in thyroid and pituitary. In Ovx females, T3 was significantly lower than in the C group. Serum T4 was significantly decreased by estradiol replacement therapy in Ovx rats, in both doses used, whereas TSH was unchanged. Eb replacement increased liver and thyroid D1 activity, but in the kidney, only the highest estradiol dose promoted a significant D1 increase. In conclusion, in males, hepatic and renal D1 activity appears to be significantly influenced by gonadal hormones, in contrast to females, in which only exogenous Eb treatment stimulated D1 activity. The comparison between pre-pubertal and adult rats suggests that serum T3 is not the main regulator of D1 activity, and other factors, besides T3 and gonadal hormones, can modulate D1 activity during murine maturation.     

Exposure of Rats to Ethanol from Postnatal Days 4 to 8: Alterations of Cholinergic Neurochemistry in the Cerebral Cortex and Corpus Striatum at Day 20

Male and female rat pups were administered ethanol (3 g/kg/dose) twice daily by intragastric intubation between postnatal Day (PN) 4 and 8. Pups were maternally reared throughout the exposure period and until sacrifice on PN20. The consequences of this growth spurt exposure to ethanol were measured by an impact upon body growth, as well as upon specific growth parameters and cholinergic neurochemical factors within the cerebral cortex and corpus striatum. Specific endpoints included muscarinic receptor binding dynamics, acetylcholinesterase (AChE) and choline acetyltransferase (CAT) activities, regional wet weights, and subcellular protein content. In male pups, ethanol resulted in a significant enhancement of body weight gain and an increase in striatal but not cortical mass. Additionally, ethanol exposure resulted in a significant increase in striatal muscarinic receptor affinity, regardless of gender. This was accompanied by evidence of a significantly greater density of striatal muscarinic receptors in males versus females, regardless of treatment. Overall, the ethanol-associated effects are suggestive of a drug-induced developmental delay. Gender-specific, treatment-independent differences were also detected in the developing brain regions. Thus, regardless of treatment, cerebral cortical S1-level protein content was found to be significantly greater in males than in females. Furthermore, there were gender-based, significant differences in AChE activity within the striatum of control pups (males greater than females). Ethanol exposure resulted in a loss of this gender-based difference. We conclude that the cholinergic neurochemical development occurring in the striatum of the female rat brain between PN4 and 8 is exquisitely sensitive to ethanol-induced developmental delays which are not remediable by 12 subsequent days of maternal rearing in the absence of ethanol exposure.     

糖基化终末产物对大鼠肾皮质基质金属蛋白酶2活性和表达的影响

的　研究糖基化终末产物 (AGEs)对肾皮质基质金属蛋白酶 2 (MMP 2 )活性及其mRNA表达的影响。方法　用链脲佐菌素制备大鼠糖尿病模型。大鼠血清蛋白与 0 .5mol/L葡萄糖孵育制备AGEs,分静脉注射AGEs(AGEs组 )、静脉注射大鼠正常血清 (阴性对照组 )和未注射大鼠 (对照组 ) 3组进行观察。ELISA测定肾皮质和血清AGEs含量 ,RT PCR检测MMP 2、金属蛋白酶组织抑制物 2 (TIMP 2 )mRNA表达水平 ,酶谱法测定MMP 2活性。结果　糖尿病大鼠肾皮质AGEs含量明显升高 ,MMP 2mRNA表达下降 ,TIMP 2mRNA表达上调 (均P <0 .0 1)。AGEs处理组大鼠肾皮质AGEs含量明显升高 (P <0 .0 1) ,MMP 2活性也明显下降 (均P <0 .0 5)。结论　AGEs通过降低大鼠肾皮质MMP 2的活性及其mRNA表达及增加TIMP 2mRNA表达 ,由此减少肾小球细胞外基质 (ECM )降解 ,可能是导致糖尿病肾病ECM积聚的原因之一     

Acetylcholinesterase,butyrylcholinesterase and paraoxonase 1 activities in rats treated with cannabis,tramadol or both

Objective:To investigate the effect of Cannabis sativa resin and/or tramadol,two commonly drugs of abuse on acetylcholinesterase and butyrylcholinesterase activities as a possible cholinergic biomarkers of neurotoxicity induced by these agents.Methods:rats were treated with cannabis resin(5,10 or 20 mg/kg)(equivalent to the active constituent A'-tetrahydrocannabinol),tramadol(5,10 and 20 mg/kg) or tramadol(10 mg/kg)combined with cannabis resin(5,10 and 20 mg/kg) subcutaneously daily for 6 weeks.Acetylcholinesterase(AChE) and butyrylcholinesterase(BChE) activities were measured in brain and serum.We also measured the activity of paraoxonase-1(PONl) in serum of rats treated with these agents.Results:(i) AChE activity in brain increased after 10-20 mg/kg cannabis resin(by 16.3%-36.5%).AChE activity in brain did not change after treatment with 5-20 mg/kg tramadol.The administration of both cannabis resin(5,10 or 20 mg/kg) and tramadol(10 mg/kg) resulted in decreased brain AChE activity by 14.1%,12.9%and 13.6%,respectively;(ii) BChE activity in serum was markedly and dose-dependenlly inhibited by cannabis resin(by 60.9%-76.9%).BChE activity also decreased by 17.6%-36.5%by 10-20mg/kg tramadol and by 57.2%-63.9%by the cannabis resin/tramadol combined treatment;(iii)Cannabis resin at dose of 20 mg/kg increased serum PONl activity by 25.7%.In contrast,tramadol given at 5,10 and 20 mg/kg resulted in a dose-dependent decrease in serum PON1 activity by 19%,36.7%,and 46.1%,respectively.Meanwhile,treatment with cannabis resin plus tramadol resulted in 40.2%,35.8%,30.7%inhibition of PONl activity compared to the saline group.Conclusions:these data suggest that cannabis resin exerts different effects on AChE and BChE activities which could contribute to the memory problems and the decline in cognitive function in chronic users.     

Inhibition of mitochondrial respiratory chain in the brain of rats after renal ischemia is prevented by N-acetylcysteine and deferoxamine

We evaluated the activities of mitochondrial respiratory chain complexes in the brain of rats after renal ischemia and the effect of administration of the antioxidants N-acetylcysteine (NAC) and deferoxamine (DFX). The rats were divided into the groups: sham (control) or renal ischemia treated with saline, NAC 20 mg/kg, DFX 20 mg/kg or both antioxidants. Complex I activity was inhibited in hippocampus, striatum, prefrontal cortex and cerebral cortex of rats 1 and 6 h after renal ischemia and that the treatment with a combination of NAC and DFX prevented such effect. Complex I activity was not altered in hippocampus, striatum, prefrontal cortex and cerebral cortex of rats 12 h after renal ischemia. Complexes II and III activities were not altered in hippocampus, striatum, prefrontal cortex and cerebral cortex of rats 1, 6 and 12 h after renal ischemia. Complex IV activity was inhibited in hippocampus, striatum, prefrontal cortex and cerebral cortex of rats 1 h after renal ischemia, but the treatment with the combination of NAC and DFX was able to prevent this inhibition. Complex IV activity was not altered in hippocampus, striatum, prefrontal cortex and cerebral cortex of rats 6 and 12 h after renal ischemia. These results suggest that the inhibition of mitochondrial respiratory chain after renal ischemia might play a role in the pathogenesis of uremic encephalopathy.     

Relationship of Putative Nicotinic Cholinergic Receptors in the Suprachiasmatic Nucleus to Levels of Pineal Serotonin N-Acetyltransferase Activity in the Normally Cycling Female, the Male, and the Ovariectomized Rat

We have examined the nocturnal increase in pineal serotonin N-acetyltransferase (SNAT) activity in the rat and the decrease in activity of this enzyme as a result of exposure of the rats to light during the nocturnal period. In females with normal ovulatory cycles and ovariectomized females, levels of the enzyme were similar during the dark (695 +/- 70 pmol/min/gland vs. 590 +/- 68) or after 20 min of lights on at night (107 +/- 5 vs. 105 +/- 8). Carbachol, a cholinergic agonist, was injected at 2400 hr (EST) into the lateral ventricle of orbitally enucleated rats. The agonist simulated the lights on effect in both intact and ovariectomized rats. Highly purified fractions of alpha-bungarotoxin, a nicotinic cholinergic antagonist were injected into either the third ventricle or bilaterally adjacent to the SCN in intact females, intact males, or ovariectomized rats. These injections had no effect on either the nighttime increase or the lights on inhibition of SNAT. This study makes the following observations: 1) As was previously demonstrated [Illnerova, H. Endocrinol. Exp. 9:141-148, 1975], ovariectomy affects neither the daytime (light period) nor nighttime (dark period) activity of pineal SNAT. This study extends previous work by demonstrating that ovariectomy also has no effect on the lights on at night decrease of SNAT activity. 2) This study confirms that intraventricular infusion of carbachol decreases the nocturnal pineal SNAT activity [Zatz, M., and Brownstein, M.J. Brain Res. 213:438-442, 1981]. 3) This study does not confirm the report that the nicotinic cholinergic antagonist alpha-bungarotoxin prevents the loss of nocturnal SNAT activity induced by turning lights on at night [Zatz, M., and Brownstein, M.J. Brain Res. 213:438-442, 1981].