Favorable change of lipid profile after carbamazepine withdrawal

OBJECTIVE

Patients treated with carbamazepine (CBZ) have increased serum levels of total cholesterol (TC), high-density lipoproteins (HDL), and low-density lipoproteins (LDL). We aimed to investigate whether these changes of serum lipids are reversible after CBZ withdrawal.

MATERIAL AND METHODS

We used a prospective, randomized double-blinded design. A total of 160 patients who had been seizure free on anti-epileptic drug monotherapy for more than 2 years were included and randomized to withdrawal or not. The intervention was completed by 150 (80 females, 53%) patients. Serum samples from before and 4 months after completed withdrawal or no withdrawal were obtained from 130 patients (63 females, 48%). Of these, 84 were treated with CBZ, 28 with valproate, nine with phenytoin, four with phenobarbital, and five with lamotrigine. Of the patients who had been treated with CBZ, 47 were randomized to the withdrawal group, and 37 were randomized to the non-withdrawal group.

RESULTS

Among the CBZ-treated patients, a significant decrease in serum levels of TC, LDL, and apolipoprotein B (ApoB) were found in the withdrawal group compared with the non-withdrawal group. Mean differences in change were as follows: TC 0.68 mmol/l (P = 0.005, CL - 1.15 to -0.21); LDL - 0.67 mmol/l (P = 0.001, CL - 1.03 to -0.29); ApoB - 0.13 g/l (P = 0.02, CL - 0.23 to -0.03). No significant changes in HDL, apolipoprotein A, and C-reactive protein were detected.

CONCLUSION

Our results indicate that CBZ may have unfavorable effects on serum levels of TC, LDL, and ApoB. However, these changes seem to be reversible even after years of treatment.

Modified Atkins diet may reduce serum concentrations of antiepileptic drugs

BACKGROUND

Modified Atkins diet is a treatment option for patients with pharmacoresistant epilepsy that is not suitable for surgery. In the last few years, we have tried dietary treatment added to antiepileptic drugs (AEDs) in adult patients with severe epilepsy.

AIM OF THE STUDY

To examine a possible pharmacokinetic interaction between the modified Atkins diet and AEDs.

METHODS

In four patients, AED serum concentrations were measured before onset and after 4 and 12 weeks on the diet. The patients used combinations of two or three AEDs, including carbamazepine, clobazam, lamotrigine, nitrazepam, oxcarbazepine, valproate, zonisamide, and topiramate. The patients did not change the type or dose of their AEDs during the diet period.

RESULTS

After 12 weeks on the diet, the average serum concentrations of the respective AEDs were reduced by 35% (range 6-46%) compared to prediet values.

CONCLUSIONS

Modified Atkins diet used as add-on therapy to AEDs in four patients with drug resistant seizures caused a considerable decrease in AED serum concentrations. In individual patients, this could be of clinical relevance, and we recommend that AED serum concentrations should be closely monitored when offering this diet to adults with epilepsy.

Reduced immunoglobulin levels in epilepsy patients treated with levetiracetam, lamotrigine, or carbamazepine

OBJECTIVES

The aim of the study was to investigate immunoglobulin levels in patients with epilepsy using the antiepileptic drugs (AED) levetiracetam (LEV), carbamazepine (CBZ), or lamotrigine (LTG).

METHODS

A total of 211 patients and 80 controls (age: 18-45 years) of both genders were included. The patients had been treated with either LEV (n = 47), CBZ (n = 90), or LTG (n = 74) monotherapy for at least 6 months. Total concentrations of immunoglobulin G (IgG), IgG subclasses (IgG1, IgG2, IgG3, and IgG4), immunoglobulin A (IgA), and immunoglobulin M (IgM) were measured. Smoking, drinking habits, and physical activity were recorded, and body mass index (BMI) was calculated.

RESULTS

A significantly lower total IgG and IgG1 was found in both men and women treated with LTG and in men on CBZ. IgG2 and IgG4 were also lower in LTG-treated women, and IgA and IgM were lower in LTG-treated men. Patients treated with LEV did not differ from the control group.

CONCLUSIONS

Low levels of immunoglobulins were found in patients with epilepsy treated with LTG or CBZ. As our group of patients consisted of otherwise healthy young adults, one should be especially aware of a possible effect of AEDs on immunoglobulin levels when treating selected patient groups, for example immunocompromised patients. Immunoglobulin concentrations should be measured in patients treated with LTG or CBZ who experience recurrent infections, and a change in medication should be considered.

Haematological side effects of antiepileptic drug treatment in patients with epilepsy

OBJECTIVES

Little is known about the haematological side effects of the newer antiepileptic drugs (AEDs), but recent case reports have raised concerns regarding the possibility of altered thrombocyte counts or function in some patients during levetiracetam (LEV) treatment. The aim of our study was to investigate haematological changes in patients treated with the newer AEDs, LEV and lamotrigine (LTG), compared with the older AEDs, valproate (VPA) and carbamazepine (CBZ).

METHODS

This cross-sectional study included 251 patients with epilepsy of both genders, aged 18-45 years, using AED monotherapy: 52 patients on LEV (31 men, 21 women), 80 on LTG (37 men, 43 women), 90 on CBZ (61 men, 29 women), 29 on VPA (15 men, 14 women), and 79 healthy controls (36 men, 43 women). Haemoglobin (Hb), white blood cells (WBC) and platelet (thrombocyte) counts were estimated. The subjects were recruited from hospitals in south-eastern Norway and Innsbruck, Austria.

RESULTS

Significantly lower platelet counts were recorded in both men and women on LEV monotherapy. In the LEV group, platelets were 14% lower (40.68 × 10(9) /l lower) than in the control group. There was no difference according to sex or age of the patients. Only minor changes in haematological parameters were observed for the other drugs investigated.

CONCLUSIONS

Both men and women treated with LEV monotherapy have lower blood platelet counts than healthy controls, with no difference in Hb or WBC. Haematological changes observed with the other AEDs were minor.

Bone health in adults with epilepsy

Patients with epilepsy have a 2-6 times greater risk of bone fractures compared with the general population. There are several potential explanations. Some fractures are caused by seizure-related injuries, or they may be associated with the osteopenic effect of reduced physical activity in patients with epilepsy. Antiepileptic drugs (AEDs), especially those that affect the liver enzymes, e.g., phenytoin, carbamazepine, phenobarbital, as well as valproate, are also associated with increased fracture rate and low bone mineral density. Many patients with epilepsy and general practitioners seem unaware of this problem. Measurements of bone density should be taken regularly in patients at risk of developing osteoporosis. Non-pharmaceutical initiatives, such as partaking in regular physical activity and eating a well-balanced diet, should be recommended. The risk of developing osteoporosis should be taken into consideration in the selection of an AED for treating a newly diagnosed patient with epilepsy.

Cardiovascular risk factors in epilepsy patients taking levetiracetam, carbamazepine or lamotrigine

OBJECTIVES

The aim of the study was to investigate risk factors for cardiovascular disease in patients with epilepsy using the new antiepileptic drug levetiracetam (LEV), compared with patients taking carbamazepine (CBZ) or lamotrigine (LTG).

METHODS

Two hundred and twelve patients and 80 controls (age: 18-45 years) of both genders were included. The patients had been treated with either LEV (n = 52), CBZ (n = 87) or LTG (n = 73) monotherapy for at least 6 months. Total cholesterol (TC), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were measured. Smoking, drinking habits and physical activity were recorded and body mass index (BMI) was calculated.

RESULTS

Neither LEV nor LTG altered TC, LDL or HDL. Both men and women using CBZ had higher TC, HDL and LDL than controls. LDL/HDL and TC/HDL ratios were unchanged. Women on CBZ and LTG had a greater BMI when compared with the control group. Patients with epilepsy recorded less physical activity and lower alcohol use than the controls.

CONCLUSIONS

Neither LEV nor LTG affected blood lipid levels, while patients treated with CBZ have higher cholesterol, HDL and LDL than controls. The patients were less physically active, and women on CBZ and LTG had higher BMI.

Phenotypic characteristics of temporal lobe epilepsy: the impact of hippocampal sclerosis

OBJECTIVES

Whether mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a condition with a unique biological background that can be delineated from other TLE, is unresolved. Here we performed a comparative analysis of two TLE patient cohorts - one cohort with HS and one without HS - in order to identify phenotypic characteristics specifically associated with MTLE-HS.

METHODS

Epidemiological data and clinical and diagnostic features were compared between patients with MTLE-HS and TLE patients without HS. When appropriate, data were compared with healthy controls.

RESULTS

Fifty-six (26%) patients were diagnosed with MTLE-HS and 162 (74%) with other TLE. Age at epilepsy onset was lower in patients with MTLE-HS (P = 0.003) than in TLE patients without HS. Incidence of simple partial seizures was higher in the MTLE-HS group (P = 0.006), as were complex partial seizures (P = 0.001), ictal psychiatric symptoms (P = 0.015), and autonomic symptoms (P < 0.001). Interictal psychiatric symptoms, including depression, were less frequent in MTLE-HS (P = 0.043). MTLE-HS patients had a higher incidence of childhood febrile seizures (FS; P = 0.043) than TLE patients without HS. In contrast, the former group had the lower frequency of first-grade family members with childhood FS (P = 0.019).

CONCLUSIONS

We identified phenotypic characteristics that distinguish MTLE-HS from other types of TLE. These characteristics will be important in diagnostics, treatment, and determination of prognosis, and provide a basis for future phenotype-genotype studies.

Differential effects of antiepileptic drugs on steroidogenesis in a human in vitro cell model

OBJECTIVES

To better understand the interaction of antiepileptic drugs and production of sex hormones, possible effects of valproate (VPA), levetiracetam (LEV) and carbamazepine (CBZ) on steroidogenesis were investigated in the human adrenal carcinoma cell line H295R.

MATERIALS AND METHODS

H295R cells were exposed to different concentrations of VPA, LEV or CBZ for 48 h. Sex hormone concentrations and mRNA expression levels were analyzed via radioimmunoassay and quantitative real time (RT)-PCR, respectively.

RESULTS

In VPA-exposed cells estradiol levels decreased in a dose-dependent manner, while testosterone and progesterone levels were unaffected. Expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), steroidogenic acute regulatory protein (StAR), CYP11a, CYP17, CYP21, 3betaHSD2, 17betaHSD1 was downregulated and expression of CYP11beta2 was upregulated. No effect on sex hormone production was observed under influence of LEV or CBZ. Expression of StAR, CYP17, CYP19 and 3betaHSD2 was downregulated in LEV-exposed cells, and expression of HMGR, CYP11beta2 and CYP17 was downregulated in CBZ-exposed cells.

CONCLUSIONS

VPA exposure resulted in a decrease in estradiol levels and a general downregulation of expression of genes encoding for enzymes early in steroidogenesis. No consistent changes were seen with LEV or CBZ exposure.

G protein beta3 subunit C825T polymorphism modifies the presentation of temporal lobe epilepsy

PURPOSE

Experimental studies suggest a role of G protein-mediated signaling pathways in epileptogenesis. A genetic variation affecting the G protein subunit Gbeta3 denoted the C825T polymorphism has been reported to increase the signaling efficiency through G(i) proteins and to modify responses to certain drugs. The C825T polymorphism has also been associated with several diseases including hypertension, diabetes type II, obesity, and major depressive disorder. In this study, we have explored whether the G protein polymorphism C825T is associated with or influences temporal lobe epilepsy (TLE).

METHODS

The study included 227 TLE patients, 186 controls, and 106 family members of TLE patients. DNA was extracted from blood samples and typing of the polymorphism was performed. Case record forms were analyzed for all the homozygote TLE patients and homozygote controls, i.e., carrying the TT genotype as well as for 28 matched TLE patients (16 females, 12 males) without the polymorphism (CC genotype).

RESULTS

Typing of the C825T polymorphism showed that 6.0% of the TLE patients, 7.0% of the controls, and 7.5% of the family members were homozygote for the polymorphism; i.e., carrying the TT genotype. TLE patients carrying the TT genotype had higher severity score on eight out of nine predefined parameters compared with the TLE patients without polymorphism, i.e., carrying CC genotype. TT genotype TLE patients also had increased body mass index, body weight, and waist circumference compared with the TLE patients carrying the CC genotype. There was no increased frequency of hypertension or diabetes.

CONCLUSIONS

There was no increased frequency of TLE between the carriers of the TT genotype compared with the healthy controls and/or family members without epilepsy. However, the TLE patients with the TT genotype showed tendencies of a more severe disease phenotype.

Valproate is an effective, well-tolerated drug for treatment of status epilepticus/serial attacks in adults

OBJECTIVE

Status epilepticus (SE) and serial attacks (SA) represent neurological emergencies, and mortality rate for SE/SA is high, ranging from 3% to 25%, depending on cause and co-morbidity. As SE/SA become more refractory to treatment over time, rapid, appropriate treatment is extremely important. Here, we report a prospective registration of the effect of intravenous (IV) valproate (VPA) on SE/SA in a group of Norwegian patients.

PATIENTS AND METHODS

Forty-one adult patients (18 males, 23 females) were included in the study. All had previously been unsuccessfully treated with diazepam. For 19, the main SE/SA seizure type was generalized tonic-clonic, while 16 had complex-partial seizures. Six had seizures that were difficult to classify. The treatment protocol recommended 25 mg/kg of VPA loading dose over 30 min, followed by continuous infusion of 100 mg/h for at least 24 h, then per oral administration. If seizures persisted after the loading dose, general anaesthesia (barbiturates/propofol/midazolam) was administered.

RESULTS

No serious side effects were reported. In 76% of the cases (31 of 41), SE/SA stopped and anaesthesia was not required. Of the patients treated within 3 h, only 5% needed anaesthesia, whereas of those treated after 3-24 h, 38% needed anaesthesia. Of those who waited for more than 24 h before treatment, 60% required anaesthesia. Furthermore, 60% of the patients who needed anaesthesia were given loading doses below 2100 mg.

CONCLUSIONS

VPA seems to be a safe, effective treatment of SE/SA, but efficacy is dependent on time lapse between symptoms and VPA treatment, and administration of a sufficiently high loading dose.

Lamotrigine in idiopathic epilepsy - increased risk of cardiac death?

OBJECTIVES

Lamotrigine (LTG) has recently been shown to inhibit the cardiac rapid delayed rectifier potassium ion current (Ikr). Ikr-blocking drugs may increase the risk of cardiac arrhythmia and sudden unexpected death. With this background, it may be of importance that in our outpatient clinic between August 1, 1995 and August 1, 2005 we registered four consecutive cases of sudden unexpected death in epilepsy (SUDEP) in non-hospitalized patients that were all being treated with LTG in monotherapy. Here we describe and discuss these cases, the relevant literature, and the reasons to question whether these events were as a result of coincidence alone.

METHODS

All the cases were collected consecutively at the outpatient clinic, Department of Neurology, Stavanger University Hospital, Norway. Clinical and pathological data were obtained and the relevant literature reviewed.

RESULTS

All were females with idiopathic epilepsy.

CONCLUSIONS

A systematic study is needed to reveal whether LTG may increase the risk of SUDEP in certain groups of patients.

Antiepileptic drugs alter reproductive endocrine hormones in men with epilepsy

Disturbances of reproductive endocrine hormones are more often found in men with epilepsy than in the general population. There is an ongoing debate whether this can be attributed to chronic use of antiepileptic drugs or to the epilepsy itself. The aim of the present study was to evaluate the degree of endocrine disturbances in men with epilepsy compared with healthy controls, and to investigate whether there was a drug-specific effect of valproate (VPA) or carbamazepine (CBZ). Men with epilepsy, 20-40 years old, having used either VPA (n = 16) or CBZ (n = 19) as monotherapy for >2 years were included and compared with age-matched controls. Men with epilepsy (VPA + CBZ) had significantly lower FSH values and higher C-peptide values compared with controls. Regarding possible drug-specific effects, the VPA treated patients had significantly higher dehydroepiandrosterone (DHEAS) levels and lower FSH and LH concentrations compared with the controls, whereas there were no differences in testosterone, testosterone/sexhormone-binding globulin (SHBG) ratio or androstenedione levels. Men on VPA also had significantly lower free carnitine/total carnitine, which may have implications for sperm motility, and also higher insulin and C-peptide concentrations. The CBZ treated patients had significantly lower testosterone/SHBG ratio than the controls. Compared with the CBZ treated patients, men on VPA had significantly higher DHEAS concentrations and lower levels of follicle stimulating hormone (FSH), luteinizing hormone (LH) as well as a lower free carnitine/total carnitine ratio. A marked age dependency was found in all three groups regarding several of the endocrine hormones. In conclusion, drug-specific endocrine effects of VPA and CBZ were found in men with epilepsy. Long-term VPA treatment leads to significant changes in DHEAS, FSH, LH, insulin, C-peptide and carnitine ratio. Long-term CBZ treatment leads to significant lower testosterone/SHBG ratio. A strict age matching were found to be of importance in the evaluation of endocrine function in men.

Alterations in semen parameters in men with epilepsy treated with valproate or carbamazepine monotherapy

Men with epilepsy are known to have reduced fertility. Whether this is drug-induced or a result of the epilepsy itself is still under debate. Few studies have been carried out on semen from men with epilepsy. The aim of the present study was first to investigate possible drug-specific effects of long-term treatment with either valproate or carbamazepine on semen quality and testicular size, and secondly to see whether the results in epilepsy patients differed from healthy fertile males. Men with epilepsy, 20-40 years old, having used either valproate (n = 16) or carbamazepine (n = 20) for >2 years, were included. The semen data of healthy fertile men without epilepsy in the same age group (n = 90) were used as controls. The semen was examined according to WHO (1999). No significant differences in semen quality were seen between men receiving either valproate or carbamazepine. However, semen from the valproate-treated, as opposed to the carbamazepine-treated, differed from controls with regard to tail abnormalities. Absolute testicular size was not significantly different between the two treatment groups. However, after correcting for changes in body mass index (BMI), the testicular size/BMI ratio was lower in the valproate-treated patients. The valproate-treated patients gained significantly more weight than the carbamazepine-treated patients after start of current medication. No differences between the patient groups were found in terms of libido/potency or number of pregnancies fathered. When comparing all epilepsy patients with healthy fertile males, there was a significant reduction in the percentage of rapidly progressive motile sperms in the semen from epileptic patients. The semen from men with epilepsy also showed significant differences from the controls regarding neck and head abnormalities of the spermatozoa.

Reproductive dysfunction in women with epilepsy: recommendations for evaluation and management

BACKGROUND

Epilepsy is commonly associated with reproductive endocrine disorders. These include polycystic ovary syndrome (PCOS), isolated components of this syndrome such as polycystic ovaries, hyperandrogenaemia, hypothalamic amenorrhoea, and functional hyperprolactinaemia.

OBJECTIVE

To summarise the currently known relations between epilepsy and reproductive endocrine disorders.

METHODS

A review of clinical experience and published reports.

RESULTS

The most likely explanations for endocrine disorders related to epilepsy or antiepileptic drugs are: (1) a direct influence of the epileptogenic lesion, epilepsy, or antiepileptic drugs on the endocrine control centres in the brain; (2) the effects of antiepileptic drugs on peripheral endocrine glands; (3) the effects of antiepileptic drugs on the metabolism of hormones and binding proteins; and (4) secondary endocrine complications of antiepileptic drug related weight changes or changes of insulin sensitivity. Regular monitoring of reproductive function at visits is recommended, including questioning about menstrual disorders, fertility, weight, hirsutism, and galactorrhoea. Particular attention should be paid to patients on valproate and obese patients or those experiencing significant weight gain. Single abnormal laboratory or imaging findings without symptoms may not constitute a clinically relevant endocrine disorder. However, patients with these kinds of abnormalities should be monitored to detect the possible development of a symptomatic disorder associated with, for example, menstrual disorders or fertility problems.

CONCLUSIONS

If a reproductive endocrine disorder is found, antiepileptic drug treatment should be reviewed to ensure that it is correct for the particular seizure type and that it is not contributing to the endocrine problem. The possible benefits of a change in treatment must be balanced against seizure control and the cumulative side effect of alternative agents.

Morphological changes in the testis after long-term valproate treatment in male Wistar rats

Uncertainty exists about the effect of antiepileptic drugs on gonadal function. In females, long-term valproate treatment has been shown to induce endocrine disturbances and an increased number of ovarian cysts. The aim of the present study was to investigate whether valproate can also induce morphological changes in the testis of male animals. In addition, possible morphological changes in the liver, heart, lungs, lymphatic nodes, pancreas, kidney or brain were studied. The carcinogenic implications were evaluated by the measurement of p53. Male Wistar rats were fed perorally with valproate mixture 200 mg kg(-1)(n= 15) or 400 mg kg(-1)(n= 20), or control solution (n= 15) twice daily for 90 days. Serum concentrations measured 4-6 hours after the last dose were 105 and 404 micromol l(-1)in low- and high-dose valproate treated animals respectively. There was a highly significant, 51% decrease (P< 0.001) in testicular weight in the high-dose treated valproate rats with no changes in the other groups. There was widespread testicular atrophy with histologically verified spermatogenic arrest in 15/20 of the high-dose valproate treated animals. No changes in the testis were seen in the low-dose valproate treated rats, nor in the control rats. There were no morphological changes in the other investigated organs. None of the groups showed over-expression of p53. In conclusion, a dose-dependent effect of chronic valproate treatment was found on testicular morphology in rats. Caution must be taken before these results can be applied to humans.

Altered ovarian function and cardiovascular risk factors in valproate-treated women

PURPOSE

Polycystic ovaries and menstrual disturbances seem to be common among women taking valproate for epilepsy. The purpose of the present study was to assess the frequency of valproate-related metabolic and endocrine disorders in different groups of women with epilepsy.

SUBJECTS AND METHODS

Seventy-two women with epilepsy and 52 control subjects from centers in three European countries (Finland, Norway, and the Netherlands) participated in the study. Thirty-seven of the women with epilepsy were taking valproate monotherapy and 35 carbamazepine monotherapy.

RESULTS

The frequency of polycystic ovaries or hyperandrogenism, or both, among valproate-treated women with epilepsy was 70% (26 of 37) compared with 19% (10 of 52) among control subjects (P <0.001). They were found in 79% (11 of 14) of obese and 65% (15 of 23) of lean women on valproate, and in 20% (7 of 35) of carbamazepine-treated women. The obese valproate-treated women with polycystic ovaries or hyperandrogenism, or both, had hyperinsulinemia and associated unfavorable changes in serum lipid levels consistent with insulin resistance.

CONCLUSIONS

Polycystic ovaries and related hyperandrogenism are frequently encountered in both obese and lean women taking valproate for epilepsy. The use of valproate is associated with risk factors for cardiovascular disease in obese women.

Up-regulation of hippocampal glutamate transport during chronic treatment with sodium valproate

Excessive glutamatergic neurotransmission has been implicated in some neurodegenerative disorders. It would be of value to know whether glutamate transport, which terminates the glutamate signal, can be up-regulated pharmacologically. Here we show that chronic treatment of rats with the anti-epileptic drug sodium valproate (200 mg or 400 mg/kg bodyweight, twice per day for 90 days) leads to a dose-dependent increase in hippocampal glutamate uptake capacity as measured by uptake of [(3)H]glutamate into proteoliposomes. The level of glutamate transporters EAAT1 and EAAT2 in hippocampus also increased dose-dependently. No effect of sodium valproate on glutamate transport was seen in frontal or parietal cortices or in cerebellum. The hippocampal levels of glial fibrillary acidic protein and glutamine synthetase were unaffected by valproate treatment, whereas the levels of synapsin I and phosphate-activated glutaminase were reduced by valproate treatment, suggesting that the increase in glutamate transporters was not caused by astrocytosis or increased synaptogenesis. A direct effect of sodium valproate on the glutamate transporters could be excluded. The results show that hippocampal glutamate transport is an accessible target for pharmacological intervention and that sodium valproate may have a role in the treatment of excitotoxic states in the hippocampus.

Chronic lamotrigine treatment increases rat hippocampal GABA shunt activity and elevates cerebral taurine levels

The mechanism of action of the antiepileptic drug lamotrigine has previously been investigated only in acute experiments and is thought to involve inhibition of voltage-dependent sodium channels. However, lamotrigine is effective against more forms of epilepsies than other antiepileptic drugs that also inhibit sodium channels. We investigated whether chronic lamotrigine treatment may affect cerebral amino acid levels. Rats received lamotrigine, 10 mg/kg/day, for 90 days. The hippocampal level of GABA increased 25%, and the activities of glutamate decarboxylase and succinic semialdehyde/GABA transaminase increased 12 and 21% (p< 0.05), respectively, indicating increased GABA turnover. The uptake of GABA and glutamate into proteoliposomes remained unaltered. The level of taurine increased 27% in the hippocampus and 16% in the frontal and parietal cortices. The activities of hexokinase and alpha-ketoglutarate dehydrogenase, remained at control values. Serum lamotrigine was 41.7+/-1.5 microM (mean+/-S.E.M.), which is within the range seen in epileptic patients. Acute experiments with 5, 20 or 100 mg lamotrigine/kg, caused no changes in brain amino acid levels. The results suggest that chronic lamotrigine treatment increases GABAergic activity in the hippocampus. The cerebral increase in taurine, which has neuromodulatory properties, may contribute to the antiepileptic effect of lamotrigine.

Valproate, but not lamotrigine, induces ovarian morphological changes in Wistar rats

Valproate (VPA) medication is associated with development of polycystic ovaries, menstrual disorders and hormonal changes in women with epilepsy. We sought to determine if changes in the ovaries also occurred in an animal model without epilepsy, and whether this effect could be related to a carcinogenic effect expressed by overexpression of p53. A potentially alternative antiepileptic drug, lamotrigine (LTG), was evaluated simultaneously. To this end, female Wistar rats were fed perorally with VPA 400 mg/kg/day (n = 15), VPA 600 mg/kg/day (n = 20), LTG 10 mg/kg/day (n = 15) or control solution (n = 15) for 90-95 days. There was a significant, dose-dependent increase in the number of follicular cysts, reduction in the number of corpora lutea and reduction of ovarian weight in the VPA group. No ovarian pathology was observed in the LTG group. In neither of the groups were morphological changes seen in other organs, nor was there any overexpression of the tumor suppressor gene p53 found. An alternative antiepileptic drug, LTG, showed no ovarian pathology, and there were no light microscopic changes in other organs, or evidence of pathologic p53 overexpression in the LTG-treated animals.

Excitatory effect of thiamin on CA1 pyramidal neurones in rat hippocampal slices in vitro

Clinically, acute thiamin deficiency may lead to Wernicke encephalopathy and fulminant cardial beriberi. Both diseases respond to high parenteral doses of thiamin. The cofactor role of intracellular thiamin diphosphate has been thoroughly investigated, but an additional acute effect of unphosphorylated extracellular thiamin has been postulated but not elucidated. In order to investigate the role of thiamin at the membrane level in the central nervous system, a study using a well-established in vitro rat hippocampal slice model was designed. Hippocampal slices were perfused with 0.5, 0.75 and 1 mM thiamin solutions for 30 min and the pre-synaptic volley, field excitatory post-synaptic potential and population spike amplitudes were recorded continuously. The results showed an acute, excitatory effect of high-dose thiamin on hippocampal neurones by significantly increasing the number of repetitive afterdischarges. Additional experiments with low concentrations of the potassium channel blocker 4-aminopyridine showed similar findings. The results support previous evidence of thiamin affecting membrane ion channel activity, probably involving potassium channels, although the precise mechanisms of action are still unclear.

Valproate-induced alterations in testosterone, estradiol and progesterone secretion from porcine follicular cells isolated from small- and medium-sized ovarian follicles

The aim of the present study was to investigate whether long-term exposure to valproate (VPA) alters follicular steroidogenesis and whether or not this effect is dependent on the degree of follicular development. Small- and medium-sized follicles were obtained from pig ovaries collected, respectively, at days 8-10 and 14-16 of oestrus cycle. Theca interna and granulosa cells were isolated from follicles and placed in the same well in the ratio 1 : 3 with or without the VPA in doses of 100, 300 and 500 micro g ml(-1). The culture medium was changed after 2, 4, 6 and 8 days. In both types of follicles, VPA caused a significant and dose-dependent reduction in both testosterone and estradiol secretion from follicular cells. In small-sized follicles, the testosterone to oestrogen ratio increased at all doses used and after all lengths of time in culture. In medium-sized follicles, a significant increase in the testosterone to oestrogen ratio was only observed at the highest dose level. All doses of VPA caused a marked inhibition of progesterone secretion after 48 hours while during long-term VPA exposure progesterone gradually increased demonstrating luteinization of cells. In conclusion, the present study demonstrates a direct effect of VPA on steroidogenesis. The effect seems to differ to some extent depending on the follicular stage of development. The elevated ratio of testosterone to estradiol suggests that VPA inhibits the conversion of testosterone to estradiol.

Long-term valproate treatment induces changes in ovarian morphology and serum sex steroid hormone levels in female Wistar rats

Long-term valproate treatment is associated with polycystic ovaries and endocrine disorders in women with epilepsy. The mechanisms responsible for these effects are unknown, but both the epilepsy itself and the drug per se may be of importance. The aim of this study was to investigate possible effects of the drug on gonadal structure and function in animals with no epileptic disorders. Three groups, each of 15 female Wistar rats, were fed perorally with a valproate mixture (50 mg / kg or 200 mg / kg) or control solution once daily for 90 days, giving mean valproate concentrations within the normal human range. A significant, 20% increase in ovary weight was found in both low- (P = 0.027) and high- (P < 0.001) dose animals together with a significantly increased number of ovarian follicular cysts. Mean serum testosterone concentration was significantly reduced in both low- and high-dose animals. There was a non-significant trend towards reduced estrogen levels, while progesterone levels were unchanged. Even if the hormonal changes are somewhat different from those in humans, the findings demonstrate that changes in gonadal structure and endocrine function also occur in intact animals indicating a drug-specific effect. Our findings encourages further studies using animal models to elucidate possible mechanisms involved in the endocrine side-effects of antiepileptic drugs.

Cerebral artery blood velocity in normal subjects during acute decreases in barometric pressure

To investigate the effect of acute changes in barometric pressure on regional cerebral perfusion we studied the middle cerebral artery (MCA) blood velocity in five healthy male volunteers by means of a low-pressure chamber. The MCA blood velocity, arterial blood and respiratory gases were measured at the barometric pressures of 1, 0.8, 0.65, and 0.5 atmospheres. The observed blood velocity (Vo) showed no systematic changes. Decreases in barometric pressure induced hypoxia and hypocapnia. When normalizing the MCA blood velocity (Vn) to a standard P(CO2) (5.3 kPa), thereby correcting for the hypoxic induced hypocapnia, we obtained an inverse relationship between cerebral artery blood velocity and arterial blood oxygen content (CaO2). The oxygen supply to the brain, estimated as the product of Vo and CaO2, decreased with lowering of the barometric pressure. However, the product of Vn and CaO2 remained constant. This suggests the existence of a regulatory mechanism attempting to maintain a constant oxygen supply to the brain during acute changes in CaO2, if the hyperventilation induced decrease in PCO2 can be omitted. In the artificial situation of a low pressure chamber, our findings are quite similar to those obtained at sea level. This indicates that the underlying mechanisms of control of cerebral blood flow do not change during acute exposure to altitude.

[Normal pressure hydrocephalus--evaluation of investigation procedures]

58 patients were investigated with a lumbar infusion test for normal pressure hydrocephalus in the department of neurology of the National Hospital between January 1991 and December 1996. We present a retrospective evaluation of the investigation protocol for these patients with suspected normal pressure hydrocephalus. The aim of the study was to find out whether specific prognostic factors could be identified by routine investigations. 20 patients had been referred to the department of neurosurgery and were subsequently shunted. A critical review of the criteria leading to surgical treatment (clinical symptoms, cerebral CT scan, infusion test, cisternography) is presented. There was no single variable which alone could discriminate normal pressure hydrocephalus from other types of hydrocephalus, or predict the outcome of shunting. A more systematic referral and clinical assessment of the patients together with a more precise evaluation of the findings and improved follow-up procedures are necessary for optimal selection of patients for surgery. The study also shows the importance of diagnosing these patients early, as delay in treatment appeared to worsen prognosis after shunting.

Cyclosporin A and brain excitability studied in vitro

PURPOSE

Seizures are frequently observed after organ transplantations. This has been attributed to a direct effect of cyclosporin A (CsA) on the brain, although other mechanisms may also be of importance. The aim of this study was to investigate possible acute and direct effects of CsA on neuronal excitability.

METHODS

Female rat hippocampal slices were perfused with CsA solutions containing 400 (n = 4), 1,000 (n = 4), 2,000 (n = 6), 8,000 (n = 8) microg/L CsA or control (n = 8) for 30 min, or penicillin, 2,000 IE/ml (n = 7). Actual concentrations of CsA were measured in the perfusate drawn from the slice chamber. To study CsA accumulation in the slices, uptake of radioactive CsA was measured in 12 living and 11 dead slices.

RESULTS

Despite a significant accumulation of CsA in the living neuronal slices, no effects were observed on prevolley, field excitatory postsynaptic potential (fEPSP), or population spike amplitude. Penicillin, however, led to epileptiform activity within 10 min in all cases. Concentrations of CsA in the perfusate from the slice chamber were about half the calculated levels, demonstrating that the slices had been exposed to actual CsA concentrations in the range of approximately 200-4,000 microg/L CsA.

CONCLUSIONS

Our results demonstrate a lack of acute effects of CsA on neuronal excitability within clinically relevant concentrations despite an active accumulation of the drug in the slices. Long-term effects on brain tissue, indirect metabolic effects, or synergistic effects may be responsible for the neurotoxicity of the drug.

Acute effects of 17 beta-estradiol on brain excitability studied in vitro and in vivo

The acute effects of 17 beta-estradiol on brain excitability were studied in vitro and in vivo utilizing rat hippocampal slices and a cat cerveau isolé preparation. The hippocampal slices were perfused with 17 beta-estradiol (10(-7)-10(-10) M) for 30 min. No effects were observed on synaptic activation and inhibition and on the response to iontophoretically applied GABA in intact and ovariectomized female rats (n = 43). In males (n = 32), however, a small (12%) but significant increase in population spike amplitude was observed after 30 min exposure to 10(-9) M 17 beta-estradiol. Higher and lower concentrations were ineffective. In vivo, no acute effects of 17 beta-estradiol on focal epileptic seizure thresholds, evoked potentials, or augmenting response were observed in the visual cortex of non-estrous female cats (n = 11; median dose 1 micrograms/kg, range 0.5 microgram/kg-10 mg/kg).

The progesterone metabolite 5 alpha-pregnan-3 alpha-ol-20-one reduces K(+)-induced GABA and glutamate release from identified nerve terminals in rat hippocampus: a semiquantitative immunocytochemical study

5 alpha-Pregnan-3 alpha ol-20-one (3 alpha-OH-DHP) reduced the depolarization-induced loss of GABA and, to a lesser extent, the glutamate-like immunoreactivities from nerve terminals in the in vitro hippocampal slice. Phenobarbital (PB) had similar effects. These results suggest that 3 alpha-OH-DHP affects presynaptic transmitter release, possibly in a barbiturate-like manner.

Comparison of 5 alpha-pregnan-3 alpha-ol-20-one and phenobarbital on cortical synaptic activation and inhibition studied in vitro

The effects of 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha-OH-DHP) and phenobarbital (PB) on synaptic excitation and inhibition in rat hippocampal slices in vitro were compared. Stimulations were made orthodromically and antidromically while we recorded extracellularly from the dendritic and the somatic layer of the CA1 region. Perfusion with 5 micrograms/ml of 3 alpha-OH-DHP for 30 min significantly increased the recurrent inhibition evoked by antidromic stimulation. The effect was most pronounced at short interstimulus intervals. The duration of the recurrent inhibition also was prolonged. There was no effect on the conditioned population spike after orthodromic paired-pulse stimulation. Furthermore, no effect was observed on the amplitude of the orthodromic fiber volley, the rate of increase in the field excitatory postsynaptic potential (EPSP) and the latency and amplitude of the CA1 population spike. Qualitative and quantitative similar findings were observed during perfusion with PB 0.1 mg/ml, (i.e., a concentration 20 times higher than that of 3 alpha-OH-DHP). Higher concentrations of PB also affected synaptic excitation. The findings suggest a similar effect of 3 alpha-OH-DHP and PB on recurrent GABA-ergic inhibition; however, 3 alpha-OH-DHP appears to be much more potent.

The effect of progesterone and its metabolite 5 alpha-pregnan-3 alpha-ol-20-one on focal epileptic seizures in the cat's visual cortex in vivo

The acute effects of progesterone and its brain metabolite 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha-OH-DHP) on focal epileptic seizures in the cat's visual cortex was studied in vivo using an unanesthetized cervaux-isolé preparation. This model made it possible to study in parallel the effect of the drugs on ictal activity and synaptic transmission. A dose-dependent increase in seizure threshold was observed after i.v. injections of both 3 alpha-OH-DHP and progesterone, 3 alpha-OH-DHP being about 20 times as potent as the latter. I.v. injections of 3 alpha-OH-DHP 1.0 mg/kg increased the median seizure threshold to 265% of baseline. While 3 alpha-OH-DHP exerted an immediate effect on seizure thresholds, the maximal effect of progesterone was delayed about 20 min. Concerning the mechanisms underlying the antiepileptic effect, three changes occurred within the effective dose range: (1) a small, but significant reduction in the presynaptic nerve volleys, (2) a reduction in the postsynaptic excitatory field potentials in the dorsal lateral geniculate nucleus and cortex, and (3) an enhanced postsynaptic inhibition. Taken together, these observations point to both pre- and postsynaptic effects, supporting the hypothesis of a barbiturate-like mechanism of action of progesterone and its brain metabolites.

Temporal distribution of seizures in epilepsy

A major problem in epileptology is why a seizure occurs at a particular moment in time. An initial step in solving this problem is a detailed analysis of the temporal distribution of seizures. Using methods and theories of stochastic processes, seizure patterns in a group of epileptic outpatients were examined for stationarity, randomness, dependency and periodicity in a prospective study. Sixteen of the 21 seizure diaries included in the study showed stationarity; 2 were non-stationary and 3 inconclusive. Eleven of the 16 stationary diaries were non-Poisson (P less than 0.005), indicating that in the majority of patients seizures did not occur randomly. The most frequently encountered phenomenon was seizure clustering. Clustering was considered when the diaries fulfilled all three criteria: (1) a positive R-test (P less than 0.001); (2) deviation from the fitted Poisson distribution towards clustering; and (3) the feature of an autoregressive process in the autocorrelogram plot. Dependency between seizure events was demonstrated in 8 of the 16 stationary diaries, computing first order transition probabilities. A detailed analysis of seizure occurrence is a major step towards a better understanding of the mechanisms underlying seizure precipitation. This is exemplified by our finding of a relation between seizure frequency and the menstrual cycle.

Triiodothyronine and brain excitability

We investigated mechanisms involved in thyroid hormone action on brain excitability. The effect of acute exposure of triiodothyronine (T3) to rat hippocampal slices in vitro was studied. No significant changes could be detected in prevolley, field excitatory postsynaptic potentials (fEPSP) and population spike amplitude, while there was a minor, nonsignificant trend toward shortening of the population spike latency time. T3 had no effect on penicillin-induced epileptiform activity. There was, however, an active accumulation of radioactively labeled T3 in the slices. A rat cervaux-isolé preparation was used to determine focal seizure thresholds in the visual cortex, and no acute (2-4 h) effects were demonstrated. No significant acute effects of T3 on brain excitability in the hippocampus and visual cortex was observed, despite an active accumulation of T3. Thus, the effect of T3 on brain excitability most likely is due to delayed effects.

A new injectable carbamazepine solution--antiepileptic effects and pharmaceutical properties

Carbamazepine (CBZ) could be dissolved in Glycofurol (polyethylene glycol monotetra-hydrofurfuryl ether) with concentrations up to 100 mg/ml, and the solutions were stable for at least 14 days. Ethanol or benzyl alcohol was added without loss in solubility, while water, human serum albumin or Intralipid always led to immediate precipitation. The effect of a CBZ/Glycofurol solution on focal seizure threshold in the visual cortex in cats was investigated using a cerveau isolé preparation. Fourteen experiments were performed using i.v. injections of CBZ with concentrations ranging from 0.2 to 20 mg/kg. In all experiments with doses greater than 1 mg/kg the CBZ/Glycofurol injections exerted a pronounced and immediate effect on the seizure threshold, while Glycofurol alone was ineffective. On average, seizure threshold increased more than 5-fold with doses in the range of 5-20 mg/kg. Investigating the effect of CBZ/Glycofurol on picrotoxin-induced seizure activity in cats, 2 injections of 5 mg/ml of CBZ immediately stopped the seizure activity as evaluated by electrocorticography, while interictal activity remained.

Effects of electroconvulsive therapy (ECT) on thyroid function parameters

Serum concentrations of thyroxine, triiodothyronine, TSH and prolactin were measured in 10 patients with affective disorders receiving ECT. Samples were drawn at -15 min, 0, +30 min, +60 min and +3 hr after ECT. A significant increase in both prolactin and TSH was observed 30 min after ECT. A small but significant decrease in triiodothyronine but no change in thyroxine was found in all post-ECT samples. The increase in TSH may be caused by an anti-dopaminergic effect of ECT at either the pituitary or the hypothalamic level.

No monthly variations in serum levels of thyroid hormones in human males

There have been very few reports on rhythmic variation in thyroid hormone concentrations with a periodicity of 4-6 weeks. In an attempt to evaluate whether such a rhythm is a general phenomenon we studied ten healthy male students with weekly blood samples over 12 weeks for T4, T3 and TSH. No rhythmicity could be demonstrated.

Association between regularly occurring complex partial seizures and thyroid function parameters

A 28-year-old man with regularly occurring clusters of complex partial seizures was studied over a total of 224 days. His seizure periods lasted 2-4 days and occurred at intervals of 5-6 weeks. Several parameters were studied. The most striking finding was an increase in the serum concentration of thyroxine prior to and during the seizure periods. The concentrations of urine catecholamines and serum cortisol also varied with the seizure periods, but these hormones increased after the seizure periods had begun. To determine if there is a general 4-6-week rhythm in thyroid hormone concentrations, 12 weekly blood samples from 10 healthy male students were analyzed. No rhythmicity was found.