Imbalance between pro- and anti-inflammatory cytokines, and between Th1 and Th2 cytokines in depressed patients: the effect of electroacupuncture or fluoxetine treatment.

BACKGROUND: An increase in inflammatory response and an imbalance between T-helper (Th) 1 and 2 functions have been implicated in major depression. The aims of the present study were to 1) study the relationship between pro- and anti-inflammatory cytokines and between Th1 and Th2 produced cytokines in depressed patients and 2) evaluate and compare the effect of treatments with electroacupuncture (EA) and fluoxetine on these cytokines. METHODS: 95 outpatients with major depressive disorder were treated for 6 weeks with EA, fluoxetine or placebo. Hamilton Depression Rating Scale (HDRS) and Clinical Global Impression (CGI) were used to assess severity and therapeutic effects. 30 volunteers served as controls. Serum cytokine concentrations were measured by ELISA. RESULTS: Increased proinflammatory cytokine interleukin (IL)-1beta and decreased anti-inflammatory cytokine IL-10 were found in the depressed patients. By contract, Th1 produced proinflammatory cytokines, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma were decreased, and Th2 produced cytokine IL-4 was significantly increased in depressed patients. The ratio of IFN/IL-4 was also increased. Both acupuncture and fluoxetine treatments, but not the placebo, reduced IL-1beta concentrations in responders. However, only acupuncture attenuated TNF-alpha concentration and INF-gamma/IL-4 ratio towards the control level. DISCUSSION: These results suggest that an imbalance between the pro- and anti-inflammatory cytokines (IL-1 and IL-10), and between Th1 and Th2 cytokines (INF-gamma or TNF-alpha and IL-4) occurred in untreated depressed patients. Both EA and fluoxetine had an anti-inflammatory effect by reducing IL-1beta. EA treatment also restored the balance between Th1 and Th2 systems by increasing TNF-alpha and decreasing IL-4.

Effects of acute and chronic administration of selective monoamine re-uptake inhibitors in the rat forced swim test.

The rat forced swim test (FST) is a model that is used extensively as a screening test for antidepressant activity. It has previously been reported that thorough analysis of behaviour in this model reveals two distinct types of active response - climbing and swimming - and that these are separately evoked by re-uptake inhibitors selective for noradrenaline (NA) and serotonin (5-HT), respectively. In the present study, utilising re-uptake inhibitors selective for NA, talsupram, and 5-HT, 5-chloro-1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)- phthalan (Lu 10-134-C), we examined if this scoring technique could detect the antidepressant potential of a selective serotonin re-uptake inhibitor (SSRI), and whether re-uptake inhibitors selective for distinct monoamine systems induce exclusive behavioural responses. We also analysed if chronic antidepressant administration for three weeks was more effective than acute treatment. We found Lu 10-134-C (40 mg/kg; PO) to be behaviourally active in this paradigm. Although treatment with talsupram (40 mg/kg; PO) resulted solely in climbing behaviour, Lu 10-134-C induced both climbing and swimming behaviour. However, chronic pre-treatment with either re-uptake inhibitor (20 mg/kg; twice daily; PO) failed to augment the response observed with acute treatment. Similarly, chronic administration of either compound was without effect on the basal, or stress-induced, serum corticosterone concentrations or anterior pituitary (AP) preproopiomelanocorticotropin (POMC) mRNA expression. These results suggest that selective monoamine re-uptake inhibition produces distinct, but not necessarily exclusive, behavioural responses in the forced swim test.

The toxicity profile of a single dose of paroxetine: an alternative approach to acute toxicity testing in the rat.

In this study we have examined the effect of a single administration of the selective serotonin reuptake inhibitor, paroxetine (120-300 mg kg(-1), orally) in a recently developed rodent model of acute toxicity testing. Reduced body-weight, food consumption, water consumption and body temperature were observed in all paroxetine-treated groups, which were reversible within 7 days. Five days after administration, a dose-dependent increase in red blood cells, haemoglobin and haematocrit was observed with the 3 higher dose levels of paroxetine, which was significant in the 240 and 300 mg kg(-1) treatment groups (P < 0.05). Hyperactivity was apparent in the first 24 hr following treatment, as was evidence of the serotonin syndrome. When the animals were sacrificed (11 days after drug administration), an increase in liver weight was observed in the highest dose. These results are in agreement with those previously observed with paroxetine at the preclinical and clinical levels. They demonstrate that this rodent model, because of its multi-parameter nature, is a useful method for examining the consequences of a single high dose of an antidepressant drug.

Varying responses to the rat forced-swim test under diurnal and nocturnal conditions.

The paradox that experiments in behavioural pharmacology employing nocturnal rodent species are carried out almost exclusively in the resting phase of the animals' circadian cycle has remained largely unexamined and unquestioned. This is despite the fact that all major physiological systems in the body are intrinsically aligned with its natural circadian rhythm. The forced-swim test (FST) is a rodent model that is used extensively as a screening test for antidepressant activity. The objectives of the present study were to examine the behaviour of rats in the FST under diurnal and nocturnal conditions and, in addition, to profile the response of neurochemical, neuroendocrine, and cellular indices of stress at time points up to 120 min following exposure to the FST. The time spent in escape-oriented activity was significantly less when animals were tested in the dark phase. The profile of serum corticosterone and adrenal ascorbic acid concentrations indicates that the animals were less stressed by the test situation during the active (i.e., dark) phase of their circadian cycle. Similarly, increases in blood enzymatic markers of stress-induced cellular damage were less marked following FST exposure in the nocturnal period. Characteristic stress-induced increases in 5-HT turnover in the frontal cortex and amygdala observed in the diurnal phase were reversed in the nocturnal period. In conclusion, circadian differences in behaviour in the FST may be related to parallel alterations in the ability of animals to adapt to exposure to stress.

Characterization of D-fenfluramine-induced hypothermia: evidence for multiple sites of action.

The effects of D-fenfluramine on core body temperature has been largely investigated under conditions of either high or low ambient temperature, whereas little research has focused on this response under normal environmental conditions. Moreover, there has been neglect in research on the mechanisms underlying changes in body temperature. In this study, we demonstrate that D-fenfluramine (5 and 10 mg/kg) induces a sustained decrease in body temperature in the rat under normal ambient temperatures. Pre-treatment with the selective serotonin reuptake inhibitor sertraline (5 mg/kg), the full 5-HT(1A) receptor antagonist 4-fluoro-N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-2-pyridinyl benzamide], WAY 100635 (0.15 mg/kg) and the 5-HT(2C) receptor antagonist benzofuran-2-carboxamidine, RO 43-0440 (2.5 mg/kg) blocked D-fenfluramine-induced hypothermia. Depletion of 5-hydroxytryptamine (5-HT) stores following treatment with the serotonergic neurotoxin parachlorophenylalanine reversed the initial hypothermic effects of D-fenfluramine but not the later effects, as D120 min post-challenge) in animals pre-treated with parachlorophenylalanine. Such findings are consistent with a requirement for D-fenfluramine uptake into 5-HT neurons followed by release of 5-HT from intracellular stores and stimulation of post-synaptic 5-HT receptors to reduce body temperature. The hypothermic response to D-fenfluramine was potentiated by ketanserin pre-treatment 30 min post-challenge but then antagonized at later time intervals. Pre-treatment with the dopamine, D(2) antagonist, haloperidol (1 mg/kg) and sulpiride (30 mg/kg) had a similar effect in blocking the hypothermia as WAY 100635, suggesting a role for dopamine D(2) receptors in the response. Pre-treatment with the alpha(2)-adrenoceptor antagonist yohimbine failed to block the hypothermic response. These results suggest multiple sites of action mediating D-fenfluramine-induced hypothermia and may be the result of a combined effect of D-fenfluramine and its active metabolite norfenfluramine affecting not only the release of 5-HT but also stimulation of post-synaptic receptors.

Lipopolysaccharide administration produces time-dependent and region-specific alterations in tryptophan and tyrosine hydroxylase activities in rat brain.

The present study examined the effect of systemic administration of lipopolysaccharide (LPS; 100 and 250 microg/kg, i.p.) on tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) activities in frontal cortex, striatum and midbrain of the rat. Enzyme activities were determined by measuring accumulation of the transient intermediates 5-hydroxytrptophan (5-HTP) and L-dihydroxyphenylalanine (L-DOPA) following in vivo administration of the decarboxylase inhibitor, NSD 1015. TPH activity was increased 2 hours after administration of LPS (100 and 250 microg/kg) in both frontal cortex and midbrain, and a secondary increase was seen in the midbrain 12 hours after challenge. LPS provoked an increase in TH activity in the midbrain only, and this was evident for up to 24 hours after LPS administration. Thus in addition to previous studies demonstrating that LPS increases in vivo NA, DA and 5-HT release, this study shows that LPS increases the activity of the rate-limiting enzymes responsible for their synthesis.

Forced swim test-induced endocrine and immune changes in the rat: effect of subacute desipramine treatment.

Previously it has been reported that forced swim test (FST) exposure activates the HPA-axis and produces alterations in both cellular and noncellular immunity in rats. Furthermore, there is evidence to suggest that pretreatment with antidepressants has a protective effect against FST-induced immune changes. The purpose of the present study was to examine the effect of subacute treatment with the tricyclic antidepressant desipramine (DMI, 5 and 10 mg/kg; I.P.) on immobility in the FST, and on FST-induced changes in endocrine and immune parameters in the rat. DMI treatment at a dose of 10 mg/kg produced a significant reduction in immobility time in the FST, while the 5 mg/kg dose was ineffective. FST exposure produced a significant increase in serum corticosterone and a decrease in adrenal ascorbic acid concentrations, neither of which were significantly attenuated by DMI pretreatment. There was a slight but nonsignificant suppression of PHA-induced lymphocyte proliferation 15 min post-FST exposure. However, DMI treatment produced a significant increase in lymphocyte proliferation at this time point. FST exposure caused a reduction in the percentage of lymphocytes and an increase in the percentage of neutrophils in the peripheral blood; DMI treatment failed to significantly alter these stress-induced changes. There was a profound reduction in relative spleen weight observed in DMI-treated animals 120 min post-FST exposure and this was accompanied by an increase in circulating RBC concentrations. In conclusion, although the FST-induced behavioral changes were normalized by DMI treatment the peripheral aberrations induced by FST exposure (with the exception of lymphocyte proliferation) were not. In addition, DMI pretreatment induced stress-like changes in corticosterone, adrenal ascorbic acid and leucocyte subpopulations in the control animals.

Effect of chronic pretreatment with the sigma ligand JO 1784 on CRF-induced changes in behaviour, neurotransmitter and immunological function in the rat.

The effects of the chronic administration of the sigma ligand JO 1784 (igmesine) CRF-induced changes in some behavioural, immune, endocrine and neurotransmitter parameters were studied. In the elevated plus maze, CRF (1.0 microgram i.c.v. daily x 5 days) induced a reduction in the number of entries and time spent on the open arms was significantly attenuated by the sigma ligand JO 1784 (3 mg/kg x 21 days) treatment. In the open field apparatus, the CRF-induced increase in the locomotor activity was also reduced by JO 1784 administration. JO 1784 treatment did not alter the concentration of the biogenic amine transmitters in the hypothalamus, nor reverse the increase in the turnover of serotonin and dopamine caused by CRF. JO 1784 treatment also failed to reverse a CRF-induced increase in the serum corticosterone, but it did reverse the reduction in phytohaemagglutinin and concanavalin A-induced lymphocyte proliferation caused by CRF but not the changes in the lymphocyte and neutrophil numbers caused by the peptide. These results demonstrate that JO 1784 has some antistress properties in CRF-treated rats.

Forced swim test-induced neurochemical endocrine, and immune changes in the rat.

The forced swim test (FST) is a behavioral paradigm that is widely used as a screening test for antidepressant activity in rodents. The objectives of the present study were to characterize the corticosterone and immune responses and in addition to examine neurotransmitter levels, in five brain regions at intervals (15, 30, 60, 90, and 120 min) following the second exposure to the FST. There was a significant but transient reduction in noradrenaline and 5-HT concentrations, in the hypothalamus 15 min post-FST exposure. 5-HT turnover in the frontal cortex and amygdala was significantly increased between 20-120 min post-FST exposure. The FST elicited a robust corticosterone response that peaked significantly at 30 min and had almost returned to baseline 120 min after exposure. There was a significant reduction in total white blood cell count 120 min after the FST, which was accompanied by a significantly reduced percentage of lymphocytes 90 and 120 min post-FST exposure. In addition, there was a significant but transient suppression of both PHA and Con A-induced lymphocyte proliferation 15 min following FST exposure. This study demonstrates that there are neurochemical changes that are coincident with the endocrine and immune changes associated with FST exposure in rats. Furthermore, this model could be used to examine the effects of manipulation of this stress response by antidepressant drugs. Such an investigation could add to our understanding of the interactions between antidepressants, stress and the neuroendocrine and immune systems.

The effects of central administration of neuropeptide Y on behavior, neurotransmitter, and immune functions in the olfactory bulbectomized rat model of depression.

The effects of subchronicly administered neuropeptide Y (NPY) intracerebroventricularly on behavioral, neurochemical, and immunological parameters were examined in sham operated and olfactory bulbectomized (OB) rats. In the untreated OB rats, an increase in ambulation, rearing, grooming, and defecation scores was found in the novel stressful environment of an "open field." Following 7 days of NPY administration, these behaviors were largely attenuated. In the elevated plus-maze apparatus, OB rats showed an increase in the number of entries into the open arms and time spent on the open arms compared with sham operated animals; NPY had no significant effect on the behavior of either sham operated or OB animals in this test. A decrease in the NA concentration was found in the amygdloid cortex of OB rats. NPY infusion significantly increased the NA concentration in amygdala, reduced 5-HIAA but increased 5-HT concentrations in the hypothalamus, and increased the dopamine level in the hippocampus. NPY administration also reversed the suppression of lymphocyte proliferation in the OB rat. However, the changes in the differential white blood cell count and the elevated phytohemagglutinin-induced chemiluminescence of mononuclear cells in the OB were not altered by NPY. These results suggest that NPY may have a modulatory effect on some behavioral, neurotransmitter, and immune aspects of the OB rat model of depression.

Influence of an n-6 polyunsaturated fatty acid-enriched diet on the development of tolerance during chronic ethanol administration in rats.

This study investigates the effects of n-6 polyunsaturated fatty acids (PUFAs), in the form of dietary Evening Primrose Oil (EPO) and safflower oil, on the development of tolerance to ethanol. The degree of fluorescence polarization of the fluoroprobes DPH, PROP-DPH, and TMA-DPH in isolated cortical synaptosomal membranes was measured. In addition, the development of tolerance, as shown by changes in synaptosomal membrane fluidity after an acute in vitro ethanol challenge, was also determined after 20 weeks of ethanol administration, either alone or together with a PUFA-enriched diet. Although the administration of EPO-enriched diet did not significantly render the inner core of the cortical synaptosomal membrane tolerant to the acute ethanol challenge, concomitant administration of ethanol and EPO was found to increase further the rigidity and tolerance to the acute ethanol challenge in the inner core. Chronic administration of safflower oil, which lacks gamma-linolenic acid (18:3, n-6) but like EPO contains linoleic acid, either alone or together with chronic ethanol had no effect on synaptosomal membrane fluidity after an acute ethanol challenge. The results suggest that gamma-linolenic acid or its metabolites may have an important role to play in the development of tolerance to chronic ethanol.

The effect of tianeptine and sertraline in three animal models of depression.

The activity of tianeptine (2.5 and 5.0 mg/kg twice daily, i.p.) and of sertraline (5.0 mg/kg, twice daily, i.p.) were assessed in three animal models of depression. In the Behavioural Despair Test, acute treatment with sertraline or tianeptine (5.0 mg/kg) significantly reduced the immobility time. In the olfactory bulbectomized (OB) rat model, chronic treatment with tianeptine (2.5 and 5.0 mg/kg) or sertraline (5.0 mg/kg) antagonized the lesion-induced hyperactivity in the "open field" apparatus. The hypothermic response to the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 0.15 mg/kg, s.c.) was significantly attenuated after chronic setraline treatment, whereas tianeptine was inactive at the 2 doses tested. Neither drug affected the hypersection of corticosterone that occurs at the light:dark interface. A reduction in the serotonin metabolite 5-HIAA was found in the hypothalamus of sertraline-treated sham rats. It can be concluded that although the neurochemical properties of sertraline and tianeptine differ, they demonstrate similar antidepressant-like activities in the Behavioural Despair and OB rat models. The lack of effect of tianeptine on the 8-OH-DPAT-induced hypothermic effect indicates that it does not induce 5-HT1A subsensitivity, contrary to most antidepressants.

Effects of an oil enriched in gamma linolenic acid on locomotor activity and behaviour in the Morris Maze, following in utero ethanol exposure in rats.

Ethanol is known to decrease the quantity of polyunsaturated fatty acids in brain membranes possibly as the repercussion of an inhibition of delta-5- and delta-6-desaturases. Consequently behavioural changes may occur. Evening Primrose Oil (EPO) which is rich in gamma linolenic acid (10% 8:3 (n-6)) was proposed to try to circumvent these deleterious effects of ethanol. An animal model of the foetal alcohol syndrome was used in which ethanol was administered throughout gestation and into the weaning period, in a milk diet. EPO was administered concurrently with ethanol to establish the effect of this essential fatty acid and ethanol on the animal's behaviour. Animals were tested at approximately 60 days of age for their responses in two different behavioural paradigms, i.e. the stressful memory task of the Morris Maze and the non-stressful activity monitor. In this study we report an increase in learning ability in male (Control-EPO and alcohol-EPO versus their control: P less than 0.00001 and P less than 0.01, respectively) and female rats (Control-EPO and alcohol-EPO versus control: P less than 0.0001 and P less than 0.00001, respectively) after administration of EPO. It was also found that ethanol plus EPO administration consistently raised the activity scores of the rats in the activity monitor (daytime activity scores for male and female rats were P less than 0.00001 and P less than 0.0001, respectively), while ethanol alone decreased the scores (male and female rats P less than 0.00001 and P less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in whole brain membranes of rats following pre- and post-natal exposure to ethanol.

The chronic effects of ethanol on the fatty acid composition of rats that have been exposed to ethanol in utero were examined. Ten female Wistar rats were fed a nutritionally adequate liquid diet for 3 weeks before mating, throughout gestation and until the offspring reached the 10th or 20th post-natal day. Whole brain lipid changes were examined at these 2 time points. On day 10, a decrease in 18:1 lipid content was found, indicating tolerance development. However, by day 20 an increase in polyunsaturated fatty acid content (20:4) was detected, indicating that ethanol may be causing an increase in membrane fluidity. Although these results are contrary to those found in adult rats following chronic ethanol administration, it seems likely that, in the immature animal, the brain is still undergoing rapid development and therefore may be affected differentially by ethanol.

The effects of chronic ethanol administration on rat liver and erythrocyte lipid composition: modulatory role of 'evening primrose oil'.

The effects of chronic administration of ethanol on the lipid composition of erythrocytes and liver of rats were investigated. Ethanol was chronically administered alone or in combination with Evening Primrose Oil (containing 10% v/v gamma-linolenic acid) in a nutritionally balanced milk diet. Chronic administration of ethanol alone significantly decreased the content of arachidonic acid in erythrocyte membranes, whereas the concomitant administration of Evening Primrose Oil reversed this effect. The triacylglycerol content was significantly increased in the microsomal fraction of the liver after chronic ethanol administration. Ethanol also significantly increased the ratio of cholesterol:cholesteryl esters in the microsomal fraction. The arachidonic acid content of the whole liver fraction was significantly reduced after chronic administration of ethanol, whereas concomitant administration of Evening Primrose Oil did not reverse this effect. The administration of Evening Primrose Oil during chronic ethanol intake may have beneficial effects, as it reverses some of the effects of ethanol on erythrocyte and hepatocyte membrane lipids which may be detrimental to health.

Psychoneuroimmunology: An area of interest for the psychopharmacologist?

Anecdotal evidence suggesting a causal relationship between psychiatric illness, environmental stress and a malfunctioning immune system goes back to antiquity. Recently, clinical and experimental studies have established the interrelationship between neuro- endocrine regulation, the immune system and abnormalities in central neurotransmission which may be deranged as a consequence of stressful events. This short review is an attempt to assess the evidence implicating altered immune responsiveness in depression and to consider the impact of different types of environmental stress in triggering the immune malfunction. While these findings are of considerable biological importance, it is presently unclear whether the immunological changes are primary or secondary to the disease states.

Behavioural teratology: post-natal consequences of drug exposure in utero.

The effects of pre-natal exposure to drugs that subsequently affect the post-natal behaviour without apparently causing noticeable brain damage forms the subject of behavioural teratology. This review summarizes the experimental studies of several investigators who showed that pre-natal administration of such psychotropic drugs as meprobamate, isocarboxazid and reserpine reduced the maze-learning ability of the mature offspring. A more detailed survey of the effects of D-amphetamine and diazepam is then given. Both drugs were not foetotoxic and only caused appreciable changes in locomotor activity of the offspring at least 14 days after birth. With the amphetamine treated rats, these changes were biphasic (elevated at 15 days and reduced at 21 days) whereas the diazepam treated animals showed a reduction in locomotor activity for at least 21 days after birth. The results of our own studies, and those of others, do not enable a correlation to be made between the effects of the various drugs on the development of specific central neurotransmitters and the behavioural deficits noticed. The review concludes with an outline proposal for screening drugs for their potential as behavioural teratogens. The possible mechanisms whereby behavioural teratogens may cause subtle changes in the maturation of the brain are also outlined.

Monamines in brain and urine of rats with hereditary hypothalamic diabetes insipidus.

Monoamine levels in brain and urine of homozygous and heterozygous diabetes insipidus (DI) rats (Brattleboro strain) were assessed. Homozygous DI rats had a higher whole brain content of serotonin than their heterozygous littermates. However, when corrected for differences in brain weight, homozygous DI also appeared to have higher brain concentrations of noradrenaline, tyrosine and GABA. The total 24 h excretion of all amines and their precursors was greater in the homozygous than in the heterozygous rats.

The action of psychotropic drugs on DOPA induced behavioural responses in mice.

The "DOPA potentiation" test in mice was investigated for its usefulness in the detection of compounds with antidepressant properties. It was found that the anti-depressant drugs imipramine, amitriptyline, 5-methylamino-acetyl-6-methyl-5,6-dihydro-phenanthridine-HCl (Org OI77) and 1,2,3,4,10,14b-hexahydro-2-methyl-dibenzo[c,f]pyrazino[1,2-a]azepine-HCl (mianserin, Org GB 94) potentiated the behavioural effect of DOPA in groups of mice which had been treated 17 h previously with the monoamine oxidase inhibitor (MAOI) iproniazid. However, the DOPA response was also potentiated by a variety of centrally acting drugs which do not have antidepressant properties (atropine, methysergide, chlordiazepoxide, apomorphine). The peptide hormones ACTH4-10 and desglycinamide lysine vasopressin had equivocal effects while melanocyte stimulating hormone release-inhibiting factor (MIF) had no effect on the DOPA response. The DOPA response was inhibited by the neuroleptics chlorpromazine and haloperidol. There appeared to be no correlation between the effects of the drugs on the behavioural responses elicited by DOPA and the changes found in the brain concentration of noradrenaline, dopamine, serotonin, gamma-aminobutyric acid, tryptophan and tyrosine. It is concluded that the "DOPA potentiation" test cannot be considered as a reliable test in the detection of anti-depressant compounds.