The effect of risperidone on the mirtazapine-induced changes in extracellular monoamines in the rat frontal cortex

BACKGROUND

The aim of our study was to understand the mechanism of clinical efficacy of the combination of an antidepressant and risperidone in drug-resistant depression.

METHODS

We studied the effect of an antidepressant (mirtazapine) and risperidone (atypical antipsychotic), given separately or jointly on extracellular levels of dopamine (DA), serotonin (5-HT) and noradrenaline (NA) in the rat frontal cortex. The animals were given a single intraperitoneal injection of risperidone (1mg/kg) and mirtazapine (10 and 20mg/kg). The release of monoamines in the rat frontal cortex was investigated using a microdialysis in freely moving animals, and monoamine levels were assayed by HPLC with coulochemical detection.

RESULTS

Risperidone increased the cortical extracellular levels of DA, 5-HT and NA. Similarly, mirtazapine dose-dependently increased the cortical extracellular levels of the monoamines studied. A combination of mirtazapine either at the higher dose (20mg/kg) or at both doses (10 and 20mg/kg) with risperidone produced a significant effect on DA and NA release, respectively compared to the effect of any drug given alone. The increase in the DA (but not NA) release induced by mirtazapine plus risperidone was partly blocked by the selective 5-HT1A antagonist WAY 100635 (0.2mg/kg).

CONCLUSIONS

Our data indicate that the increase of cortical extracellular levels of DA and NA by combined administration of mirtazapine and risperidone may be of crucial importance to the pharmacotherapy of drug resistant depression, and that, among other mechanisms, 5-HT1A, 5-HT2A, α2-adrenergic and histamine H1 receptors may play some role in this effect.

A partial lesion of the substantia nigra pars compacta and retrorubral field decreases the harmaline-induced glutamate release in the rat cerebellum

The aim of the present study was to examine the influence of a partial lesion of both the substantia nigra pars compacta (SNC) and retrorubral field (RRF) on the glutamatergic transmission in the cerebellum and tremor induced by harmaline in rats. 6-Hydroxydopamine (6-OHDA, 8 μg/2 μl) was injected unilaterally into the region of the posterior part of the SNC and RRF. Harmaline was administered in a dose of 30 mg/kg ip on the 8th day after the operation and the extracellular level of glutamate was measured by microdialysis in vivo in the cerebellar vermis. Harmaline induced glutamate release in the cerebellum. The lesion which encompassed 23-37% neurons in the anterior SNC, 52-54% in the posterior SNC and 47-55% in the RRF did not influence the basal extracellular glutamate level but decreased the harmaline-induced release of this neurotransmitter. Tremor evoked by harmaline was also visibly inhibited by the above lesion. The results of the present study seem to indicate that midbrain dopaminergic neurons influence glutamatergic transmission in the cerebellum which may be important for generation of the tremor induced by harmaline.

Effects of adenosine receptor antagonists on the in vivo LPS-induced inflammation model of Parkinson's disease

The study shows effects of the nonselective adenosine A1/A2A receptor antagonist caffeine and the selective A2A receptor antagonist KW6002 on LPS-induced changes in the extracellular levels of dopamine (DA), glutamate, adenosine, hydroxyl radical, and A2A receptor density in the rat striatum. Intrastriatal LPS (10 μg) injection decreased extracellular level of DA and increased the level of adenosine, glutamate, and hydroxyl radical on the ipsilateral side 24 h after LPS administration. Caffeine (10 and 20 mg/kg i.p.) and KW6002 (1.5 and 3 mg/kg i.p.) given once daily for 6 days and on the 7th day 2 h before and 4 h after LPS injection reversed the LPS-induced changes in extracellular levels of DA, adenosine, glutamate, and hydroxyl radical production. Moreover, LPS-induced decrease in the striatal A2A receptor density was increased by caffeine and KW6002. In order to show the late LPS effect on oxidative damage of DA neurons, the contents of DA, DOPAC, HVA, and hydroxyl radical were determined 72 h after LPS (10 μg) administration into both striata. LPS decreased striatal and substantia nigra content of DA, DOPAC, and HVA while increased striatal but not nigral content of hydroxyl radical. Caffeine (20 mg/kg) and KW60002 (3 mg/kg) given once daily for 6 days and on the 7th day 2 h before and 4 h after intrastriatal injection of LPS normalized the content of DA and its metabolites in both brain regions as well as decreased LPS-induced increase in the striatal level of hydroxyl radical. In conclusion, our data demonstrated antioxidant effects of caffeine and KW6002 in the inflammatory model of PD.

Accumbal and pallidal dopamine, glutamate and GABA overflow during cocaine self-administration and its extinction in rats

We investigated the changes in dopamine (DA), glutamate and γ-aminobutyric acid (GABA) during cocaine self-administration in rats implanted with guide cannulae into the nucleus accumbens and ventral pallidum. After stabilized cocaine self-administration, separate groups of rats underwent extinction (10 days) procedure in which cocaine infusion was replaced by saline injections. With using a 'yoked' procedure, the effects of cocaine or its withdrawal on the level of neurotransmitters were evaluated by dual-probe microdialysis. Repeated cocaine administration reduced basal glutamate levels in the nucleus accumbens and ventral pallidum, whereas it did not affect basal accumbal DA levels. Only rats that self-administered cocaine had increased basal GABA overflow in both examined brain structures. Active or passive cocaine administration elevated extracellular accumbal DA, however, the extent of cocaine-evoked DA level was significantly higher in rats that self-administered cocaine while both groups of animals showed also an attenuation of GABA level in the nucleus accumbens. On day 10 of extinction training, rats previously given cocaine revealed decreases in the basal accumbal concentration of glutamate while the basal GABA levels were significantly enhanced as compared with baseline of saline-yoked controls. Potassium depolarization delayed the reduction of the accumbal and pallidal extracellular glutamate levels in the active and passive cocaine groups. The present data indicate that changes in DA and GABA neurotransmission during maintenance phase mirror the motivational aspects of cocaine intake. Depending on acute (24 hours) or late (10 days) cocaine withdrawal, different neurotransmitter systems (i.e. glutamate or GABA) seem to be involved.

Effect of the conceptus on uterine prostaglandin-F2alpha and prostaglandin-E2 release and synthesis during the periimplantation period in the pig

The present study was conducted to evaluate the effect of the conceptus on uterine prostaglandin-F2alpha (PGF2alpha) and prostaglandin-E2 (PGE2) release and the expression of prostaglandin synthase enzymes during the periimplantation period in the pig. A surgically generated model with conceptuses developing in only one of the uterine horns was created. The highest concentration of PGF2alpha and PGE2 was found in the gravid uterine horn, compared with the non-gravid horn and the intact horn of cyclic gilts. Endometrial concentration of both PGs in pregnant gilts was elevated regardless of the conceptus in the uterine horn, whereas only myometrial PGE2 concentration increased during pregnancy. Expression of prostaglandin-E2 synthase (mPGES-1) mRNA in the endometrium was upregulated during the oestrous cycle, while protein expression presented a similar pattern to that of PGE2 concentration in the uterine flushings. Prostaglandin-F2alpha synthase (PGFS) mRNA and protein expression in the endometrium did not differ between pregnancy and oestrous cycle but PGFS mRNA in the myometrium increased during pregnancy both in the gravid and the non-gravid uterine horns. We suggest a local effect of the conceptus on PG release pathways but also a more systemic effect within the whole uterus with regard to PG synthesis and accumulation in uterine tissues.

Effect of adenosine A(2A) receptor antagonists on L-DOPA-induced hydroxyl radical formation in rat striatum

A(2A) adenosine receptor antagonists have been proposed as a new therapy for Parkinson's disease (PD). Since oxidative stress plays an important role in the pathogenesis of PD, we studied the effect of the selective A(2A) adenosine receptor antagonists 8-(3-chlorostyryl)caffeine (CSC) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385) on L: -3,4-dihydroxyphenylalanine (L: -DOPA)-induced hydroxyl radical generation using in vivo microdialysis in the striatum of freely moving rats. L: -DOPA (100 mg/kg; in the presence of benserazide, 50 mg/kg) given acutely or repeatedly for 14 days generated a high level of hydroxyl radicals, measured by HPLC with electrochemical detection, as the product of their reaction with p-hydroxybenzoic acid (PBA). CSC (1 mg/kg) and ZM 241385 (3 mg/kg) decreased haloperidol (0.5 mg/kg)-induced catalepsy, while at low doses of 0.1 and 0.3 mg/kg, respectively, they did not display an effect. CSC (1 and 5 mg/kg) and ZM 241385 (3 and 9 mg/kg) given acutely, or CSC (1 mg/kg) and ZM 241385 (3 mg/kg) given repeatedly, increased the production of hydroxyl radicals in dialysates from rat striatum. Both acute and repeated administration of CSC (0.1 and 1 mg/kg) and ZM 241385 (3 mg/kg) decreased L: -DOPA-induced generation of hydroxyl radicals. However, a high single dose of either CSC (5 mg/kg) and ZM 241385 (9 mg/kg) markedly potentiated the effect of L: -DOPA on hydroxyl radical production. The increase in hydroxyl radical production by acute and chronic injection of CSC and ZM 241385 may be related to the increased release of dopamine (DA) and its metabolism in striatal dialysates. Similarly, increased DA release following a single high dose of CSC or ZM 241385 appears to be responsible for augmentation of L: -DOPA-induced hydroxyl radical formation. Conversely, the inhibition of L: -DOPA-induced production of hydroxyl radical by single and repeated low doses of CSC or repeated low doses of ZM 241385 may be related to reduced DA metabolism. Summing up, A(2A) antagonists, used as a supplement of L: -DOPA therapy, depending on the dose used, may have a beneficial or adverse effect on ongoing neurodegenerative processes and accompanying oxidative stress.

Paradoxical effects of adenosine receptor ligands on hydroxyl radical generation by L-DOPA in the rat striatum

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with selective loss of dopaminergic neurons in substantia nigra pars compacta. Among the proposed mechanisms of dopaminergic degeneration, oxidative stress is believed to play an important role. On the other hand, L-DOPA used as the main medication in PD and overproduction of dopamine (DA) in striatal neurons could elicit toxic effects due to formation of free radicals (FRs). Adenosine, an endogenous neuromodulator was shown in various experimental models to have neuroprotective properties. In our study, we investigated the role of adenosine A(1) and A(2A) receptor ligands in hydroxyl radical generation by L-DOPA in the rat striatum. The hydroxyl radical was assayed by HPLC-ED as a product of its reaction with p-hydroxybenzoic acid (PBA). Intrastriatal infusion of L-DOPA(50 microM) markedly increased dialysate level of DA and 3,4-dihydroxybenzoic acid (3,4-DHBA). An adenosine A(1) receptor agonist N(6)-cyclopentyladenosine (CPA, 25-50 microM), nonselectiveA(1)/A(2A) receptor agonist 2-chloroadenosine (2-CADO, 50-100 microM), and selective A(2A) receptor agonist CGS 21680 (25-50 microM) decreased the level of 3,4-DHBA. A non-selective A(1)/A(2A) adenosine receptor antagonist caffeine (100 microM) produced similar effect on 3,4-DHBA level. At the same time, CPA and 2-CADO, but not CGS 21680 or caffeine, decreased L-DOPA-induced DA release. The adenosine receptor ligands alone only weakly changed extracellular DA level and did not influence hydroxyl radical production. However, they showed scavenging activity in Fenton reaction in vitro. The primary caffeine metabolite in rodents, 1,3,7-trimethyl uric acid (1,3,7-mUA) decreased both, DA synthesis and 3,4-DHBA level. Thus, paradoxically, both agonists of A(1) receptor and agonist of A(2A) receptor as well as antagonist of A(1) and A(2A) receptors (caffeine), all decreased generation of FRs. Our study suggests that a decrease in hydroxyl radical generation caused by adenosine receptor ligands results from attenuation of L-DOPA-induced DA release or from their scavenging activity.

Quantitative expression of lysophosphatidic acid receptor 3 gene in porcine endometrium during the periimplantation period and estrous cycle

Lysophosphatidic acid (LPA) belongs to the group of lipid messengers, which act via lysophosphatidic acid receptor 3 coupled to G-proteins. The participation of LPA3 in reproductive biology was revealed in mice and has not been studied in gilts. The present study was performed to evaluate the gene expression of LPA3 by a quantitative real-time PCR technique in the endometrium during different stages of pregnancy (days 6-30) and corresponding days of the estrous cycle (days 2-20) as well as in periimplantation period in pigs with surgically detached uterine horns. Based on the most conserved segments of human and rodent LPA3 we obtained a product containing 619bp (GenBank: EF137953), which exhibited high homology with human and rodents sequences. The highest transcript level was noted on days 10-12 of gestation in comparison to remaining periods and during pregnancy on days: 6-7, 8-9, 10-12 and 13-14 in comparison with the corresponding days of the estrous cycle. Higher mRNA level was noted in the horn containing embryos compared to the contralateral horn, where embryos did not develop. The results imply the important role of receptor LPA3 during early pregnancy.

[Comorbidity of eating disorders and bipolar affective disorders]

Eating disorders--anorexia nervosa, bulimia nervosa and eating disorders not otherwise specified (EDNOS) occur usually in young females. The significant pathogenic differences between patients who only restrict food, and patients with binge eating and compensatory behaviours, such as vomiting and purging were described. The prevalence of bipolar affective disorders--especially bipolar II and bipolar spectrum disorders (BS) may reach 5% in the general population. About half of the depressive episodes are associated with a "mild" bipolar disorder, and such a diagnosis is suggested by impulsivity and mood-instability. Previously, majority of research on the comorbidity between eating and affective disorders focused on depressive symptomatology, however difficulties in the reliable assessment of hypomania may obfuscate the estimation of the co-occurrence of eating disorders with BS. Epidemiological studies suggest the association between BS and eating disorders with binge episodes (bulimia nervosa, anorexia- bulimic type and EDNOS with binge episodes). Co-occurrence of such disorders with depressive symptoms probably suggests the diagnosis of BS, not recurrent depression. Bulimic behaviours, impulsivity and affective disorders might be related to the impairment of the serotonergic neurotransmission, which may result from the genetic vulnerability and early life trauma. Currently, the first-line pharmacological treatment of co-occurring eating disorders with binge episodes and BS are selective serotonin reuptake inhibitors. However in some cases, the use of mood-stabilising agents as monotherapy or in combination with serotonergic drugs may be helpful.

[Enzymatic tests for alkaline and acid phosphatase in gingival tissues in workers of the Chelm Cement Plant]

Using histochemical methods the activity of alkaline and acid phosphatase was determined in the gingivae of 38 workers aged from 26 to 59 years employed in work with greatest exposure to dust. The control group comprised 11 men aged 23 to 49 years living in Chelm or in its vicinity, not exposed to cement dust. The activity of alkaline phosphatase in the group with exposure and with deep gingivitis of lower intensity was very high, while it was lower in the group with highest intensity of the inflammatory process. The activity of acid phosphatase increased with increasing intensity of pathological changes.

[Localization of retained teeth in radiogram]

The purpose of the study was evaluation of various possibilities of localization of retained teeth. The study was carried out on 86 patients referred to the Department of Conservative Stomatology, Institute of Stomatology Medical Academy in Lublin. Retained teeth were discovered in them accidentally or in examinations for various symptoms. On the basis of history data, clinical examination and radiological findings the following localization of retained teeth was recognized: 1) lateral or anterior part of the mandible, 2) lateral or anterior part of the maxilla, 3) maxillary sinus or its vicinity, 4) ascending ramus or condular process, 5) vicinity of the lower orbital margin and piriform fossa.

[Congenital absence of permanent teeth]

In 76 patients treated at the Department of Conservative Stomatology, Institute of Stomatology, Medical Academy in Lublin congenital absence of anlages of permanent teeth was found. The patients were aged 8 to 18 years, including 49 girls and 27 boys. In the whole group absence of 214 teeth was noted, i.e. 136 in girls and 78 in boys. In the examinations it was observed that congenital absence of permanent teeth was more frequent in girls than in boys, 2) most frequently only one tooth was absent in a given patient, 3) upper teeth were lacking more frequently than lower teeth, and absence of right teeth was more frequent than left teeth, 4) the greatest group among absent teeth were upper lateral incisors, while second upper molars in the maxilla were least frequently absent.

[Usefulness of radiological examinations in the diagnosis of supernumerary teeth]

Existence of the supernumerary teeth has been found in 39 persons at the age of 8 to 69. There were 61.6% of the cases at the age when dentition exchange takes place and 38.4% of the cases during maturity. Clinical and radiological examinations have been carried out in these patients. The radiograms obtained have been found useful in detection, description and treatment of this dental anomaly.

[Rare case of supernumerary teeth]

A case of supernumerary teeth existence in maxilla and mandible in 21-years' old female patient has been described. The possibility of utilization one of them situated in the dental arch as an abutement for prosthetic crown has been considered.