Binding of paroxetine to the serotonin transporter in membranes from different cells, subcellular fractions and species

The binding of [(3)H]-paroxetine to membrane serotonin transporter (SERT) has been studied in membranes from different sources and subcellular fractions. From rat were membranes from venous blood platelets, brain total cortex, brain microsomes, brain crude and purified synaptosomes. Membranes were obtained from venous blood platelets from human volunteers and from brain cortex tissue from neurosurgery (cerebral lobectomies following craniocerebral injuries). The main finding was that the K (D) of paroxetine binding to the SERT was the same for platelet and nerve ending (synaptosomal) membranes. That parameter was significantly lower in membranes from brain microsomes and cortex total tissue. No species related difference was found, where comparison was possible, between human and rat tissue. The equality of K (D) of paroxetine binding to blood platelet membranes and to membranes from nerve endings appears to encourage the use of such membranes as a model for brain SERT. Binding at two different temperatures for several of the fractions suggests that paroxetine-SERT interaction is entropy-driven.

Potentiation of brain serotonin activity may inhibit seizures, especially in drug-resistant epilepsy

In spite of the large number of antiepileptic drugs (AEDs) actually available, the problem of drug-resistant epilepsy has not been solved. No AEDs are efficacious in patients with pharmacoresitant epilepsy, so new hypothesises about the mechanisms of pharmacoresistance are needed. In the last years the ideas on the role of brain serotonin in epilepsy have been turned upside down: increasing the available brain serotonin is thought now to have an antiepileptic effect. Antidepressant drugs like selective serotonin re-uptake inhibitors, i.e., fluoxetine, have proved to be useful in seizure control. Tryptophan (Trp), an essential amino acid, is the only brain precursor of serotonin, it competes with the other large neutral amino acids (LNAAs) for the carrier of blood-brain barrier (BBB). Our own data has shown a lowering of plasmatic LNAA levels in epileptic patients, on the basis of these results we could estimate a decrease of a 1/3 in the Trp brain intake rate in epileptics in respect to controls. Increasing plasmatic Trp levels increases brain serotonin synthesis. Trp and 5-hydroxytryptophan (5-HTP) were tested as an add on in epilepsy, but the clinical outcome was controversial. Free amino acids are not fully adsorbed by the gastro-intestinal system, furthermore LNAAs, and also 5-HTP is a LNAA, compete to cross the intestinal membrane for the same carrier, like for the BBB. The best way to increase the plasmatic Trp level is a protein rich in Trp and poor in the other LNAAs. Unfortunately Trp is a limited amino acid in proteins. We report the clinical results obtained by adding a whey protein to the antiepileptic therapy of drug-resistant epileptic patients: alpha-lactoalbumin, rich in Trp and poor in the other LNAAs.

Is the antiepileptic effect of the ketogenic diet due to ketones?

For many years, the ketogenic diet, including recent variants such the medium-chain triglyceride (MCT) diet, has been used with good clinical results in the management of refractory epilepsies, particularly in children. The antiepileptic effects of the diet, like the antiepileptic effects of starvation, have been attributed to accumulation of ketones, and there are experimental data in animal models to support this hypothesis. Recently, new data about the neuroendocrine response to the acute phase reaction (stress) have emerged, indicating involvement of various neuropeptides, including neuropeptide Y (NPY), which is considered as an endogenous anticonvulsant. The release of NPY is also stimulated by nutrients in the gut, particularly fats. Long-chain and, to a greater extent, medium-chain triglycerides, which are components of the ketogenic diet, stimulate NPY secretion. This effect may explain the improvement in seizure control after starvation, use of the classical ketogenic diet, and use of the MCT diet.

Successful Treatment of Epilepsy with Serotonin Reuptake Inhibitors: Proposed Mechanism

The widely used antidepressants Specific Serotonin Reuptake Inhibitors (SSRI) have been tried with success as anticonvulsants in cases of nonsymptomatic epilepsy. This attempt was performed on the basis of experimental data suggesting the involvement of impairments of the serotonin system in the genesis of epilepsy. This overview summarizes the clinical data and presents biochemical and neurochemical evidences suggesting the mechanism of the therapeutic effects of SSRI in nonsymptomatic epilepsy. In particular, studies on blood-borne neutral amino acids and platelet serotonin transporter (SERT) in epileptics suggest: (a) That a decreased brain availability of tryptophan may be related to some types of epilepsy. (b) That reduction of the density of SERT may be a homeostatic reaction in the brain following epileptic seizures.

Immature oocyte in-vitro maturation: clinical aspects

The development of immature oocyte collection techniques for in-vitro maturation (IVM), combined with novel culture techniques, opens new possibilities for assisted reproductive technology. Optimization of clinical management of IVM cycles will enhance pregnancy outcome, so that IVM might become an effective alternative assisted reproduction treatment for infertile patients irrespective of the cause of infertility. Parameters such as age and baseline antral follicular count are predictive of outcome and should be used as selection criteria for IVM treatment. Women with polycystic ovary disease and normo-ovulatory patients at risk of developing ovarian hyperstimulation syndrome might benefit from earlier retrieval of oocytes followed by IVM and embryo transfer. HCG priming before oocyte retrieval seems beneficial in terms of oocyte yield and maturational competence, and may increase the harvest of mature oocytes and lead to better endometrial synchronization with the developing embryo. The timing of aspiration may be crucial in IVM and selection criteria for follicle size at aspiration need defining prospectively for infertility type. Finer calibre aspiration needles and low aspiration pressure yield more oocytes. A combination of natural cycle IVF with IVM is a promising, mild and inexpensive assisted reproduction treatment, widely accessible the infertile population.

The anticonvulsant effect of citalopram as an indirect evidence of serotonergic impairment in human epileptogenesis

Some evidence would indicate that a serotonergic deficit may be involved in epileptogenesis. A preliminary trial of citalopram, a selective inhibitor of serotonin reuptake, was carried out. Citalopram 20mg/day was given to 11 non-depressed patients with poorly controlled epilepsy as an add on treatment with an open label design for 8-10 months. The median seizure frequency dropped by 55.6% in the whole group, with nine patients improving by at least 50%. No adverse reactions occurred with the exception of mild drowsiness. There were no changes of post-treatment as compared to pre-treatment AED serum concentrations. Although controlled studies are required to confirm the anticonvulsant effect of citalopram, these findings may be regarded as an indirect evidence of serotonergic impairment in human epileptogenesis.

Use of cetrorelix in combination with clomiphene citrate and gonadotrophins: a suitable approach to 'friendly IVF'?

BACKGROUND

With the recently introduced GnRH antagonists, soft stimulation protocols on the basis of clomiphene pretreatment should be possible as the pituitary remains fully sensitive at the beginning of the cycle.

METHODS

A prospective trial was carried out on 107 patients undergoing IVF treatment using the multiple dose GnRH antagonist protocol (cetrorelix), clomiphene citrate, and either HMG (n = 54) or recombinant FSH (rFSH) (n = 53). Different stimulation protocols were used to find the most appropriate one for clinical application.

RESULTS

Both treatment groups, HMG and rFSH, yielded comparable results concerning gonadotrophin dose, stimulation days and pregnancy rate. A mean number of 6.34 +/- 4.4 metaphase II oocytes was retrieved and a mean number of 2.45 +/- 0.65 embryos was transferred. However, the overall rate of premature LH surges was 21.5% (defined as measurement of LH >10 IU/l and progesterone >1 ng/ml) which is unacceptable for clinical practice.

CONCLUSIONS

Increasing the daily cetrorelix dose from 0.25 to 0.5 mg might decrease the number of premature LH surges. Soft stimulation protocols with clomiphene should be used cautiously.

Impact of ovarian stimulation on corpus luteum function and embryonic implantation

The luteal phase has been found to be defective in virtually all the stimulation protocols used in in-vitro fertilization (IVF), indicating that common mechanisms might be involved despite the use of different drugs. A normal luteal phase is characterised by a normal hormonal environment, normal progesterone secretion by the corpus luteum and adequate endometrial secretory transformation. Luteinizing hormone supports the corpus luteum and luteal luteinizing hormone (LH) levels have been found to be reduced in human menopausal gonadotrophin (HMG), gonadotrophin-releasing hormone (GnRH)-agonist/HMG and GnRH-antagonist/HMG protocols, probably leading to an insufficient corpus luteum function. Supraphysiological steroid serum concentrations routinely observed in stimulated cycles may adversely affect LH secretion and induce a luteal-phase defect. In turn, these high steroid serum concentrations may advance early luteal-phase endometrial development leading to embryo-endometrial asynchrony and decreased pregnancy rates in IVF cycles.

Psychostimulants and epilepsy

PURPOSE

The aim of this article is to review the literature on the effects of psychostimulants in epileptic subjects in order to reach a consensus statement regarding the use or abuse of these substances.

METHODS

Psychostimulant substances have been considered the drugs that share the ability to produce excitation of the CNS leading to convulsions. The stimulation may be at cortical, brainstem, or spinal levels. In this article, the following cortical stimulants are analyzed and discussed: cocaine, amphetamine and related agents, caffeine, cannabinoids, and psychedelic drugs. This review is based on research done using pharmacological textbooks and Medline.

RESULTS

The use of cocaine is associated with the occurrence of seizures. The reported frequency varies from 1% to 40% of addicted subjects, based on the typology of the considered study. Amphetamines and related drugs rarely induce epileptic seizures at therapeutic doses, but seizures may occur after the first dosing. Caffeine at high doses may induce epileptic seizures because of its adenosine receptor-antagonizing properties. Marijuana, at variance with other psychostimulants, owing to its serotonin-mediated anticonvulsant action, could have a medical use for the treatment of epilepsy. Psychedelic compounds rarely induce epileptic seizures, but the most common clinical CNS complication after ingestion of ecstasy is the occurrence of seizures.

CONCLUSIONS

The use of psychostimulants, except for marijuana, can induce single or multiple seizures in healthy subjects.

Plasma and follicular fluid concentrations of LHRH antagonist cetrorelix (Cetrotide) in controlled ovarian stimulation for IVF

Cetrorelix was administered in differing daily dosages for controlled ovarian stimulation. The dosage levels were 3 mg (9 cycles), 1 mg (19 cycles), 0.5 mg (43 cycles), 0.25 mg (46 cycles) and 0.1 mg (7 cycles). In the 3 mg, 1 mg and 0.5 mg group the respective median plasma concentrations of cetrorelix on the day of oocyte pick-up (OPU) were 2.10 ng/ml, 1.42 ng/ml and 0.88 ng/ml and 1.03 ng/ml, 0.46 ng/ml and 0.49 ng/ml on the day of embryo transfer (ET). In the 0.25 mg and 0.1 mg groups plasma cetrorelix levels were below the limit of quantification. The cetrorelix concentrations in follicular fluid (FF) in the 0.25 mg group were detectable in only 14 out of 44 samples, while in the 0.1 mg group no detectable concentrations could be obtained. We also examined 80 cycles after single doses of 5 mg (7 cycles), 3 mg (42 cycles), and 2 mg (31 cycles) cetrorelix. On the day of OPU the respective median plasma concentrations of cetrorelix were 0.57 ng/ml, 0.62 ng/ml, and 0.56 ng/ml, and 0.61 ng/ml and 0.28 ng/ml on the day of ET in the 5 mg and 3 mg groups. In the 2 mg group, the plasma concentrations fell to below limits of quantification in 8/9 samples on the day of ET. In 26 out of 27 FF samples cetrorelix was detectable in the 3 mg single dose group (median level: 0.69 ng/ml).

Avoidance of multiple pregnancies after ovulation induction by supernumerary preovulatory follicular reduction

OBJECTIVE

To evaluate the effect of supernumerary preovulatory follicular reduction as an approach to avoid multiple pregnancies in ovulation induction or superovulation cycles.

DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENT(S)

In 26 cycles, 24 patients underwent ovulation induction or superovulation with either clomiphene citrate or hMG.

INTERVENTION(S)

Selective follicle aspiration was performed before hCG administration.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate and numbers of multiple pregnancies.

RESULT(S)

A mean number of 4.5 follicles with a diameter > or =15 mm and a mean number of 4.5 follicles with a diameter < or =14 mm were observed before hCG administration. A mean number of 2.3 follicles with a diameter > or =15 mm and a mean number of 1.8 follicles with a diameter < or =14 mm were aspirated before the hCG administration. Seven singleton pregnancies (26.9% per cycle) ensued from the treatment.

CONCLUSION(S)

Aspiration of supernumerary follicles after ovulation induction or superovulation seems to be a valid approach to avoid multiple pregnancies without affecting pregnancy rate.