Kinga Burda

Influences of chronic venlafaxine, olanzapine and nicotine on the hippocampal and cortical concentrations of brain-derived neurotrophic factor (BDNF)

Brain-derived neurotrophic factor (BDNF) is a key neurotrophic factor in the brain. It plays an important role in the etiopathogenesis and pharmacotherapy of mental disorders, such as depression or schizophrenia. In recent years, studies have shown that cognitive processes, which are impaired in the course of mental disorders, significantly change BDNF levels in the brain. Administered to rats at a dose of 20 mg/kg (b.d. for 5 weeks), venlafaxine (VEN) increases BDNF levels in the hippocampus and cortex, compared to controls. Administered at a dose of 0.5 mg/kg (b.d. for 5 weeks), olanzapine (OLA) significantly increases BDNF levels in both the cortex and the hippocampus. Similarly, nicotine (NIC) administered at a dose of 0.2 mg/kg (b.d. for 5 weeks) increases BDNF concentrations in both the hippocampus and the cortex. Combined administration of NIC with VEN or OLA does not increase BDNF levels in the hippocampus or the cortex. Based on our study, it can be claimed that BDNF mediates behavioral responses only to drugs used individually and participates in the antidepressant and procognitive effects of the study compounds. BDNF also initiates plastic changes and modulation of synaptic activity in rat brains.

Influence of aripiprazole on the antidepressant, anxiolytic and cognitive functions of rats

Recent research has suggested that cognitive disorders are a persistent trait of mental illnesses such as schizophrenia. Cognitive deficits in the course of schizophrenia may be due to the disease and/or drug therapy, especially with old-generation drugs. Several clinical experiments have indicated the beneficial effects of new-generation antipsychotics on cognitive processes in patients treated for mental disorders. Aripiprazole is a new, atypical antipsychotic with a unique mechanism of action, which may have positive effects on cognitive functions. The aim of this study was to investigate the effects of aripiprazole on spatial memory in the Morris water maze and antidepressant activity in the Porsolt test. In addition, we examined whether aripiprazole had any side effects in the chimney test. The behavioral tests showed that aripiprazole improved spatial memory in rats and had antidepressant and anxiolytic effects after a single treatment; however, aripiprazole impaired motor coordination after repeated administration. We concluded that aripiprazole could be an effective antipsychotic for the treatment of patients with schizophrenia or bipolar disorder who have associated anxiety and cognitive deficits.

Concomitant use of tramadol and venlafaxine – evaluation of antidepressant-like activity and other behavioral effects in rats

BACKGROUND The aim of this study was to evaluate antidepressant-like effect (Porsolt test), locomotor activity and motor coordination of joint administration of tramadol (TRM) and venlafaxine (VEN) in rats. METHODS The tests were performed on male Wistar rats after single and chronic treatment (7 and 14 days) with TRM intraperitoneally (ip) and VEN orally (po) administered once a day. The controls were given 0.5% carboxymethylcellulose (CMC) solution (0.5 ml per rat, ip and po). RESULTS It was found that combination of TRM (5 mg/kg ip) with VEN (20 mg/kg po) caused an increased antidepressant effect compared to TRM and VEN administered alone, with no effect on locomotor activity or motor coordination in rats, which may be of clinical significance. It was also observed that reduced time of active swimming of animals in Porsolt test with an increased dose (10 and 20 mg/kg) and time of administration (7 and 14 days) of TRM were correlated with a decreased locomotor activity in rats. It may indicate the development of tolerance to TRMs antidepressant effect in rats during chronic treatment with doses higher than 5 mg/kg. CONCLUSION It can be expected that combination of low doses of TRM and VEN could potentially be feasible and relatively safe in cases with acute pain with co-existing depression, however, further investigations are needed.

Cognitive effects of GABAergic antiepileptic drugs.

Many patients undergoing long-term treatment of epilepsy complain of memory disorders, which entail worse quality of life. The risk factors generating memory disorders include: morphological brain damage, the duration and course of epileptic seizures (conscience disorders), the time of diagnosis (the risk is greater if epileptic seizures start early in life), drug resistance, the presence of interseizure changes in the EEG in the form of sharp-wave discharges or sharp spike-wave/ slow spike-wave complexes and improper pharmacotherapy (exceeding the admissible concentration of drugs in blood serum, polytherapy). GABAergic neurotransmission of older antiepileptic drugs (barbiturates, benzodiazepines) makes them particularly prone to produce modest, but statistically significant disruption of cognitive processes. This explains the search for new antiepileptic drugs that will improve, or at least not impair, cognitive functions. The improvement of cognitive functions by new generation antiepileptic drugs results, among others, from their non-GABAergic mechanisms: they influence the ion channels and glutaminergic transmission.

Concomitant use of carbamazepine and olanzapine and the effect on some behavioral functions in rats

As shown in clinical studies, combinations of first generation normothymics (carbamazepine - CBZ) with atypical neuroleptics (olanzapine - OLA) lead to improvements in approximately half of patients treated for relapses of bipolar affective disease. Our previous studies have shown OLA to have an antidepressant effect when administered at a dose of 0.5 mg/kg only upon single administration; the effect did not last throughout chronic administration, whereas CBZ administered at a dose of 30 mg/kg showed an antidepressant effect only after 7 days of administration. As shown in our previous studies, both OLA and CBZ improve memory in rats but only after chronic administration. The improved antidepressant effect of many drugs, including OLA and CBZ used in combined therapy - as observed in our clinic - as well as confirmed evidence of OLAs and CBZs positive effects on cognitive functions in humans and animals substantiated commencement of research on defining the effect of combined administration of OLA and CBZ on sedation (tested in a locomotor activity test), antidepressant effect (Porsolt test) and spatial memory (Morris test) in animals. The tests were performed on male Wistar rats. It was found that in combined administration of CBZ and OLA for 7 and 14 days, OLA would completely prevent the CBZs sedative effect. With combined administration of CBZ and OLA, both as a single dose and after prolonged treatment for 7 days, a significant reduction in immobility time was observed. Combined administration of CBZ and OLA did not improve memory in rats that received these drugs in a single dose, whereas statistically significant differences were observed in the chronic experiments. It can be assumed that the observed effects of combined administration of CBZ and OLA may be due to the pharmacokinetic interactions, but further studies are necessary to confirm these assumptions.

Effect of valproic acid and environmental enrichment on behavioral functions in rats

Deficits of cognitive functions are perceived as an important pathogenic factor of many neurological and psychiatric diseases. Such symptoms can be a result of a disease process or appear due to applied medication. Epilepsy is a disease in which cognitive deficits can occur before first seizures, during seizures and remissions. Valproic acid (VAL, CAS 77372-61-3) is a medicine applied in order to control epileptic seizures and mood stabilizing in bipolar disorders and mania. Its activity is related to the effect on neurotransmission of many systems. The present study was conducted to investigate whether enriched environment (EE) conditions affect learning and memory, and influence the antidepressant effect in rats. VAL improves spatial memory upon repeated administration both in the rats housed in standard conditions (SC) (after 21 days of treatment) and those housed in enriched environment (as early as after 14 days of treatment). VAL has an antidepressant effect on the forced swimming test both in the rats housed in standard conditions and those housed in EE. In rats housed in EE, the antidepressant effect occurred much earlier (as early as after 7 days ofVAL administration). It is worth noting that VAL has a low profile of adverse effects (Activity Meter, chimney test). The correlations observed may be translated into clinical effects, leading to new, more effective VAL therapies in depression or memory disorders in patients with underlying epilepsy.

Effect of lamotrigine and environmental enrichment on spatial memory and other behavioral functions in rats.

Epileptic patients are at risk of experiencing cognitive deficits as a result of pharmacotherapy as well as etiology of epilepsy. Antiepileptic drugs increase inhibitory neurotransmission and reduce the responsiveness of neurons, and thereby may have a negative impact on memory. The enriched environment intensifies exploration of the new area behavior, which may have a positive impact on spatial memory in rats. Depression is among the most common affective disorders in epileptic patients, and using antidepressant drugs together with antiepileptics brings about the risk of interactions and intensifying side effects, The aim of the study was to assess the effects of lamotrigine (CAS 84057-84-1, LTG) (10 mg/kg i.p.), a new anticonvulsant with antidepresssant and neuroprotective properties, for memory and other behavioral functions in rats in standard and enriched environments (EE). LTG improved spatial memory upon repeated administration of the drug both in the rats housed in standard conditions and those housed in EE. Exposure to an enriched environmentsignificantly improved spatial learning. LTG showed antidepressant effect on the forced swimming test both in the rats housed in standard conditions and those housed in EE. In rats housed in EE the antidepressant effect occurred earlier. LTG had a low profile of adverse effects (activity meter, chimney test).

Interactions of nicotine and drugs used in the treatment of mental illnesses with respect to cognitive functions.

Cognitive disorders in the course of mental illnesses are one of the most important and most difficult therapeutic problems related to those illnesses and they regard attention, memory, learning and sensory modulation. The limited number of nicotinic receptors (subtypes alpha7 and alpha4beta2) seems to cause the incidence and exacerbation of cognitive deficits in such patients. In patients with schizophrenia, the impairment of cognitive processes is also a side-effect of neuroleptics. The characteristics and intensity of the negative effect of antipsychotics on cognitive functions depends on the pharmacological action of those drugs and on the effect on dopamine and serotoninergic receptors in particular. Cognitive function deficits observed in various mental illnesses can be modified with the use of nicotine. A cholinergic neurotransmission system is a common transmission system in the central nervous system. The effect of nicotine on other neurotransmission systems--the dopaminergic and glutaminergic systems--seems to be significant for their efficacious cognitive effects in combination with antipsychotic drugs. Nicotine may also alleviate symptoms of depression, as it amplifies serotoninergic and noradrenergic neuronal activity. When studies on treating cognitive disorders with nicotine are carried out, nicotines interactions with other drugs used in therapy of those disorders must be taken into account as well as the effect of this substance on neurotransmission systems.