Extracellular glutamate levels in the hypothalamus and hippocampus of rats after acute or chronic oral intake of monosodium glutamate

Using brain microdialysis we studied the effect of high doses of monosodium glutamate (MSG) on the extracellular concentration of glutamate in the hypothalamus and in the hippocampus of freely moving rats. MSG at 4 g/kg (40% solution) given by gavage caused a significant increase in plasma (5.3 +/- 0.4-fold, P < 0.01) and extracellular glutamate in the hippocampus (4.2 +/- 0.6-fold, P < 0.01) and in the hypothalamus (8.9 +/- 1.7-fold, P < 0.01) compared to control rats receiving a 40% sucrose solution (10 ml/kg). The peak increase was found within 40 min after MSG administration then declining to baseline in the next 80 min. No changes were found in glutamate tissue concentrations. Twenty-one days after ad libitum MSG intake with the diet (approximately 4 g/kg) no changes were found, in plasma, in extracellular and tissue concentration of glutamate in the hypothalamus compared to rats fed with a normal diet. Glutamate release induced by 200 mM KCl was not modified as well. Histological analysis of Nissl-stained brain tissue slices did not reveal any obvious cell loss in the hippocampus after acute or chronic MSG administration.

Effect of d-fenfluramine on the indole contents of the rat brain after treatment with different inducers of cytochrome P450 isoenzymes

The effects of pretreatment with inducers of hepatic cytochrome P450 isoenzymes (phenobarbital, dexamethasone and beta-naphthoflavone) on the metabolism of d-fenfluramine (d-F) and its acute and long-lasting indole-depleting effects were studied in rats, in an effort to obtain further information on the importance of hepatic drug metabolism in relation to its neurochemical actions. Twenty-four hours after the last dose of each inducer, rats were injected with d-F hydrochloride (5 mg/kg, IP) and killed at various times thereafter for parallel determination of indoles and drug concentrations in plasma and brain. Additional rats were treated as above and killed 1 week after d-F hydrochloride (5 and 10 mg/kg) to study the recovery of indole in the cortex, a particularly sensitive brain area. Phenobarbital and beta-naphthoflavone and, to a lesser degree, dexamethasone, stimulated the metabolism of d-F, as evidenced by a decrease in plasma and brain areas under the curve (AUC) compared to vehicle-treated rats. This indicated that multiple isoenzymes are capable of mediating the drug's metabolism, primarily by N-dealkylation to d-norfenfluramine (d-NF). None of the inducers raised plasma and brain AUC of the nor-derivative, and in fact phenobarbital and particularly beta-naphthoflavone reduced it. These different effects were even apparent in rats given d-NF (2.5 mg/kg), indicating that both phenobarbital and beta-naphthoflavone also stimulate the sequential metabolism of the nor-metabolite (by N-deamintaion) which, however, is apparently enhanced most actively by beta-naphthoflavone-inducible forms of P-450.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmaceutical prescriptions in Italy

Pharmaceutical prescriptions are quite different in four European countries: Italy, France, Germany, and the United Kingdom. In particular, in 1992, among the 50 most sold products by value, only seven active principles are common to these four countries. In Italy, in 1994, there has been a substantial change in pharmaceutical prescriptions, since, for the first time, drugs have been reimbursed by the National Health System (NHS) on the basis of efficacy. As a result of this new policy, the 50 most-sold products by value have changed dramatically in the first five months of 1994. The pharmacologic and economic implications of this change are discussed.

Treatment of idiopathic membranous glomerulopathy

The treatment of membranous nephropathy, the most common form of glomerular diseases causing nephrotic syndrome in adults, is still debated. A considerable percentage of patients have a spontaneous remission of the disease and reduction of urinary protein excretion with time. Studies in the past have indicated that prednisone may have beneficial effects, but this has not been confirmed by more recent investigation. Others have studied the association of methylprednisolone with cyclophosphamide or chlorambucil, but results are conflicting. The main reasons for the conflicting data are the variety of clinical presentations of the disease and the different study populations. Most trials performed so far have not included enough patients in each category to adequately detect differences between treatment groups and placebo groups. Several studies with few numbers of patients reported that cyclosporine effectively reduced proteinuria and may have less long-term toxicity than more conventional immunosuppressants. This finding, however, must be verified by appropriate clinical trials.

[The decalogue of the post-manual]

On the 1st January the Italian Health Ministry published a new Drug List, where marketed pharmaceutical products had been re-classified by the ad hoc Commission (CUF, Commissione Unica del Farmaco). Drugs were divided in three categories: A. effective drugs (drugs able to prolong life or improve quality of life), provided by the NHS without any charge for the consumer; B. drugs whose therapeutic role is less "critical", and or could be a second option, for which the consumer is expected to pay 50% of the price; C. compounds without any documented efficacy, not reimbursed by the NHS. H. drugs to be prescribed only by the hospital services. One of the key members of CUF proposed a comprehensive evaluation of the work done, which has been seen as a "revolution", with hot debates from all concerned parties (including the strong opposition from the pharmaceutical industry and private pharmacists). Overall, the number of efficacious drugs freely available for the majority of patients has tripled, while the exclusion (into class C) of many (often very expensive) useless drugs is expected to decrease the overall public drug expenditure.

Effects of synthetic retinoids and retinoic acid isomers on the expression of alkaline phosphatase in F9 teratocarcinoma cells

Expression of ALP in F9 teratocarcinoma cells is induced by all-trans retinoic acid (ATRA) (Gianni' et al., Biochem. J. 274: 673-678, 1991). The specific ligand for retinoic acid related receptors (RXRs), 9-cis retinoic acid (9-cis RA), and three synthetic analogs binding to the alpha, beta and gamma forms of the retinoic acid receptors (RARs), AM580, CD2019, and CD437, were used to study their effects on alkaline phosphatase (ALP) enzymatic activity and mRNA levels. At concentrations close to the Kd for their respective receptors, 9-cis RA, AM580 (the RAR alpha agonist) and CD437 (the RAR gamma agonist) clearly upregulate the expression of the ALP gene, whereas the effect of CD2019 (the RAR beta agonist) is very modest. A specific inhibitor of the RAR alpha, Ro 41-5253, completely blocks the induction of ALP triggered by AM580, while it has minor effects on the upregulation caused by ATRA, 9-cis RA, CD437 and CD2019. The induction of ALP observed with the various retinoids is inhibited by the contemporaneous treatment with dibutyryl cAMP. The levels of the RAR alpha and gamma transcripts are unaltered, while RAR beta mRNAs are induced by ATRA, AM580, CD437 and to a lower extent by 9-cis RA and CD2019.

Acute noise stress reduces [3H]5-hydroxytryptamine uptake in rat brain synaptosomes: protective effects of buspirone and tianeptine

Acute noise stress decreased [3H]5-hydroxytryptamine ([3H]5-HT) uptake in synaptosomes from rat hypothalamus, hippocampus and cerebral cortex. The decrease was due to the maximum rate of [3H]5-HT uptake, which peaked 30 min after stress and partly returned to resting values within 4 h, with no changes in affinity (Km values). No changes in [3H]paroxetine binding and basal [3H]5-HT release were found in stressed rats. Tianeptine, given at the dose of 10 mg/kg 1 h before stress, counteracted the noise-induced decrease of 5-HT uptake, since it increased [3H]5-HT uptake in both resting and stressed animals, but did not prevent the rise in plasma corticosterone of stressed rats. Buspirone pretreatment had no effect on [3H]5-HT uptake in resting rats but prevented the noise-induced decrease in [3H]-HT uptake. Diazepam did not modify either the basal or the noise-induced reduction in [3H]5-HT uptake. The evidence that treatments reducing extrasynaptic 5-HT, by increasing its reuptake (tianeptine) or reducing its release (buspirone) in innervated regions are able to modify the stress-induced decrease in 5-HT uptake, further confirms the importance of serotonin in the mechanisms mediating neurochemical responses to stress.

The effects of single and repeated anorectic doses of 5-hydroxytryptamine uptake inhibitors on indole levels in rat brain

1. The effects of acute and repeated equiactive anorectic doses (ED50) of recently marketed 5-hydroxytryptamine (5-HT) uptake inhibitors on the content of brain indoles were compared in rats in relation to the brain regional concentrations of unchanged drug and its known active metabolite. 2. Single intraperitoneal (i.p.) doses of the anorectic ED50 of fluoxetine (35 mumol kg-1), fluvoxamine (60 mumol kg-1), paroxetine (20 mumol kg-1) and sertraline (49 mumol kg-1) slightly reduced brain 5-hydroxyindoleacetic acid (5-HIAA), with regional differences, this being compatible with 5-HT uptake blockade. Only fluvoxamine and sertraline significantly enhanced the content of 5-HT in the cortex. 3. The regional sensitivity to the acute effect of a given drug was not related to any preferential drug distribution, as these compounds distributed almost uniformly in the brain areas considered (cortex, striatum and hippocampus). 4. Repeating the same doses twice daily, i.p. for 14 days, however gave a different picture, fluvoxamine having little or no effect on the content of indoles and fluoxetine, paroxetine and sertraline lowering both 5-HT and 5-HIAA in all the brain regions compared to pair-fed control animals, 1 h after the last dose. 5. One week later only fluoxetine-treated animals still had reduced brain 5-HT, this probably being related to the accumulation of its main metabolite norfluoxetine in rat brain after chronic dosing. 6. Further studies on the relationship between the long-term neurochemical changes and anorectic activity are required but it appears from these results that anorectic drugs with similar acute effects on 5-HT uptake may differ in their long-term effects on 5-HT mechanisms.

Neurochemical mechanism of action of anorectic drugs

Studies with dexfenfluramine, an anorectic agent which releases 5-hydroxytryptamine (5-HT) from nerve terminals and inhibits its reuptake, have considerably increased our knowledge of the role of 5-HT in feeding control. 5-HT1B receptors mediate the satiating effect of dexfenfluramine, whereas the mechanism by which 5-HT uptake inhibitors such as fluoxetine and sertraline cause anorexia is not clear. Anorexia induced by (+)-amphetamine, phentermine, diethylpropion and phenylpropanolamine seems to be the result of their ability to increase the release of noradrenaline and/or dopamine from nerve terminals and inhibit their reuptake or, in the case of phenylpropanolamine, to stimulate directly alpha 1-adrenoceptors. It has been suggested that beta- and alpha 1-adrenoceptors and D1 dopamine receptors are involved in their effect on food intake. The difficulties of extrapolation across species limit our knowledge of the mechanism of the anorectic action in humans. Significant advances in the treatment of feeding pathology will be linked to identifying new receptor types and subtypes for neurotransmitters and quantifying and modelling eating disorders such as binge-eating and food craving.

Prognosis of untreated patients with idiopathic membranous nephropathy

BACKGROUND

Defining the most appropriate treatment for patients with idiopathic membranous nephropathy is a matter of controversy. The course of the disorder is often benign, and the immunosuppressive regimens used in some patients have uncertain benefits and substantial risks. We studied the natural history of idiopathic membranous nephropathy in patients who received only symptomatic therapy.

METHODS

We prospectively studied 100 consecutive patients (68 men and 32 women; mean [+/- SD] age, 51 +/- 17 years) with biopsy-proved idiopathic membranous nephropathy. The patients received diuretic or antihypertensive drugs as needed, but no glucocorticoid or immunosuppressive drugs. We examined the patients and measured their urinary protein excretion and serum creatinine concentrations every 6 months for a mean of 52 months.

RESULTS

Twenty-four (65 percent) of the 37 patients followed for at least five years had complete or partial remission of proteinuria; in 6 others (16 percent), end-stage renal disease developed, and they required dialysis. As calculated by the Kaplan-Meier method, the estimated probability (+/- the standard error of the estimate) of retaining adequate kidney function was 88 +/- 5 percent after five years and 73 +/- 7 percent after eight years. The prognosis was poorer in men and in patients over 50 years of age, but not in patients with the nephrotic syndrome, hypertension, or hypercholesterolemia.

CONCLUSIONS

Most untreated patients with idiopathic membranous nephropathy maintain renal function for prolonged periods and are likely to have spontaneous remission. These results do not support the use of glucocorticoids and immunosuppressive drugs in patients with idiopathic membranous nephropathy.

Pharmacological activities of chlorpromazine involved in the inhibition of tumour necrosis factor production in vivo in mice

Chlorpromazine (CPZ) was shown to inhibit tumour necrosis factor (TNF) production in vivo. Several drugs sharing one of the various pharmacological activities of CPZ were tested in endotoxin-treated mice. It was found that alpha-blockers (prazosin, idazoxan, phenoxybenzamine), antiserotoninergics (methysergide, methergoline) and antihistamine (chlorpheniramine, promethazine) also inhibited TNF production indicating that the effectiveness of CPZ in protecting from endotoxin shock is due to its multiple pharmacological activities.

The role of d-norfenfluramine in the indole-depleting effect of d-fenfluramine in the rat

The importance of d-norfenfluramine in regard to the indole-depleting action of d-fenfluramine has not been well studied in sensitive animal species. The present study therefore examined the intensity and time course of the neurochemical effects of i.p. injected d-fenfluramine (2.5 and 5 mg/kg) and d-norfenfluramine (2.5 mg/kg) in vehicle- and SKF-525A-pretreated rats, relating the effects to the brain concentration-time profiles of the drug and its active metabolite. At the lower dose d-fenfluramine caused only a small, short-lasting decrease in brain serotonin (5-HT) without affecting the 5-hydroxyindoleacetic acid (5-HIAA). Higher doses affected both 5-HT and 5-HIAA (50-60 and 30-40% reductions, respectively), the effect being maximal for at least 8 h. d-Norfenfluramine reduced the brain content of 5-HT and 5-HIAA less (by about 30%) than 5 mg/kg d-fenfluramine did. Brain concentrations of d-norfenfluramine at the time of the maximal depletion of indoles were close to those of the metabolite after 5 mg/kg d-fenfluramine, indicating that the acute indole-depleting effects did not depend solely on the brain concentrations of its nor-metabolite. SKF-525A changed the metabolite-to-parent drug ratios in brain without appreciably influencing the action of d-fenfluramine. However, the maximum decrease in indole content caused by 2.5 mg/kg d-fenfluramine in SKF-525A-pretreated rats was only 12% of the control level, although the brain concentration of unchanged drug was comparable to that after 5 mg/kg d-fenfluramine in vehicle-pretreated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Anorectic effect and brain concentrations of D-fenfluramine in the marmoset: relationship to the in vivo and in vitro effects on serotonergic mechanisms

The present study investigated the anorectic activity of d-fenfluramine (d-F) and the relationship with brain levels of unchanged drug and its metabolite d-norfenfluramine (d-NF) in marmosets, relating them to neurochemical effects on the serotoninergic system. d-F and d-NF were equally active in reducing food intake (ED50 about 3 mg/kg, p.o.). However, the brain concentrations of the metabolite required to reduce food intake after synthetic d-NF were more than twice those after d-F, indicating that d-NF contributes to but does not completely explain the anorectic effect of d-F. At this dose d-F did not appreciably modify the serotonin (5-HT) and 5-hydroxyindoleacetic (5-HIAA) contents of the brain regions examined, except for a slight enhancement of 5-HIAA in hippocampus. In vitro in brain cortical synaptosomes d-F inhibited [3H]5-HT uptake more potently than d-NF, as in other species. d-F and d-NF showed similar potency in stimulating [3H]5-HT release, in a Ca++ dependent manner. The tritium released by d-F and d-NF appeared to be mainly unmetabolized [3H]5-HT. Like in other species the marmoset too has saturable and specific [3H]d-F binding sites, for which d-NF has lower affinity. d-F and d-NF have low affinities for 5-HT receptor subtypes, except that d-NF has appreciable affinity for 5-HT1C and 5-HT1D receptors. Unlike in rodents but similarly to primates in the striatum the pharmacology of 5-HT receptors seems to correspond to the 5-HT1D subtype.(ABSTRACT TRUNCATED AT 250 WORDS)

Anorectic activity of fluoxetine and norfluoxetine in mice, rats and guinea-pigs

The present study aimed to establish the role of the metabolite norfluoxetine in the anorectic activity of fluoxetine, and to relate the anorectic doses (ED50) to the brain concentrations of the parent drug and its metabolite. Fluoxetine showed anorectic activity at increasing intraperitoneal doses (ED50 = 39.1, 34.7 and 21.7 mumol kg-1 in mouse, rat and guinea-pig, respectively) and norfluoxetine was slightly more active (24.3, 22.9 and 19.1 mumol kg-1, respectively) in all three species. In terms of maximum concentration (Cmax) and area under the curve (AUC) within the experimental period (0-90 min), brain concentrations varied widely and were poorly related to the dose; guinea-pig appeared to be much more sensitive to fluoxetine than was mouse or rat. Administered norfluoxetine was present in the brain of the three species in approximately the same order as fluoxetine, i.e. lower in guinea-pig than in mouse or rat. The Cmax and AUC of norfluoxetine after fluoxetine administration was 50-60% of the values after an equiactive dose of norfluoxetine in mouse and guinea-pig, and more than 80% in rat.

Progress report on the anorectic effects of dexfenfluramine, fluoxetine and sertraline

This progress report on the anorectic effect of serotoninergic indirect antagonists compares the action of D-fenfluramine, fluoxetine and sertraline and their N-dealkylated metabolites. Brain levels of drugs and their metabolites were measured after equi-active anorectic doses. Fluoxetine and sertraline inhibit 5-HT uptake in vitro with a potency which is at least one order of magnitude higher than for D-fenfluramine while all three drugs release 5-HT from synaptosomes and the active concentrations are closer to the brain concentrations reached after anorectic doses. However, a number of differences have been observed between D-fenfluramine and fluoxetine regarding the mechanisms of 5-HT release. Furthermore fluoxetine affected storage of 5-HT in vesicles much more than D-fenfluramine did. The anorectic effect induced by fluoxetine was not antagonized by antiserotoninergic drugs. No evidence of an involvement of CCK in the anorectic effect of D-fenfluramine was found when food intake was determined in rats previously submitted to food deprivation.