Ghanshyam N. Pandey

Platelet serotonin-2 receptor binding sites in depression and suicide

In order to examine the role of serotonin-2 (5HT2) receptors in depression and suicide, we determined 5HT2 receptors using 125I-lysergic acid diethylamide (LSD) as the binding ligand in platelets obtained from 20 normal control and 23 drug-free depressed patients. Our results indicate significantly increased 125I-LSD binding sites (Bmax) in the platelets of depressed patients compared with normal control subjects. We also observed that a subgroup of depressed patients with a recent history of suicide attempts or suicidal ideation had significantly higher 5HT2 binding sites as compared with nonsuicidal depressed patients and normal controls. There were no significant differences in the apparent dissociation constant (Kd) values in the platelets of depressed patients compared with normal control subjects. To examine if the baseline 5HT2 receptors are related to either the severity of illness or treatment response, we determined the relationships of the baseline Bmax and Kd with baseline Hamilton Depression Rating Scale (HDRS) and Brief Psychiatric Rating Scale (BPRS) scores and change in scores after treatment. We found no significant correlation between baseline Bmax and Kd with the baseline HDRS or BPRS scores or change in these scores after psychoactive drug treatment. These results thus indicate increased platelet 5HT2 receptors in depression, but much more so in depressed patients with suicidal ideation or attempts.

Antidepressants reverse corticosterone-mediated decrease in brain-derived neurotrophic factor expression: Differential regulation of specific exons by antidepressants and corticosterone

Earlier studies have implicated brain-derived neurotrophic factor in stress and in the mechanism of action of antidepressants. It has been shown that antidepressants upregulate, whereas corticosterone downregulates, brain-derived neurotrophic factor expression in rat brain. Whether various classes of antidepressants reverse corticosterone-mediated downregulation of brain-derived neurotrophic factor is unclear. Also not known is how antidepressants or corticosterone regulates brain-derived neurotrophic factor expression. To clarify this, we examined the effects of various classes of antidepressants and corticosterone, alone and in combination, on the mRNA expression of total brain-derived neurotrophic factor and of individual brain-derived neurotrophic factor exons, in rat brain. Normal or corticosterone pellet-implanted (100 mg, 21 days) rats were injected with different classes of antidepressants, fluoxetine, desipramine, or phenelzine, intraperitoneally for 21 days and killed 2 h after the last injection. mRNA expression of total brain-derived neurotrophic factor and of exons I-IV was measured in frontal cortex and hippocampus. Given to normal rats, fluoxetine increased total brain-derived neurotrophic factor mRNA only in hippocampus, whereas desipramine or phenelzine increased brain-derived neurotrophic factor mRNA in both frontal cortex and hippocampus. When specific exons were examined, desipramine increased expression of exons I and III in both brain areas, whereas phenelzine increased exon I in both frontal cortex and hippocampus but exon IV only in hippocampus. On the other hand, fluoxetine increased only exon II in hippocampus. Corticosterone treatment of normal rats decreased expression of total brain-derived neurotrophic factor mRNA in both brain areas, specifically decreasing exons II and IV. Treatment with desipramine or phenelzine of corticosterone pellet-implanted rats reversed the corticosterone-induced decrease in total brain-derived neurotrophic factor expression in both brain areas; however, fluoxetine reversed the decrease only partially in hippocampus. Interestingly, antidepressant treatment of corticosterone pellet-implanted rats increased only those specific exons that are increased during treatment of normal rats with each particular antidepressant. We found that although corticosterone and antidepressants both modulate brain-derived neurotrophic factor expression, and antidepressants reverse the corticosterone-induced brain-derived neurotrophic factor decrease, antidepressants and corticosterone differ in how they regulate the expression of brain-derived neurotrophic factor exon(s).

Proinflammatory cytokines in the prefrontal cortex of teenage suicide victims

Teenage suicide is a major public health concern, but its neurobiology is not well understood. Proinflammatory cytokines play an important role in stress and in the pathophysiology of depression-two major risk factors for suicide. Cytokines are increased in the serum of patients with depression and suicidal behavior; however, it is not clear if similar abnormality in cytokines occurs in brains of suicide victims. We therefore measured the gene and protein expression levels of proinflammatory cytokines interleukin (IL)-1β, IL-6, and tissue necrosis factor (TNF)-α in the prefrontal cortex (PFC) of 24 teenage suicide victims and 24 matched normal control subjects. Our results show that the mRNA and protein expression levels of IL-1β, IL-6, and TNF-α were significantly increased in Brodmann area 10 (BA-10) of suicide victims compared with normal control subjects. These results suggest an important role for IL-1β, IL-6, and TNF-α in the pathophysiology of suicidal behavior and that proinflammatory cytokines may be an appropriate target for developing therapeutic agents.

Brain-derived neurotrophic factor and tyrosine kinase B receptor signalling in post-mortem brain of teenage suicide victims

Teenage suicide is a major public health concern, but its neurobiology is not very well understood. Stress and major mental disorders are major risk factors for suicidal behaviour, and it has been shown that brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase B (TrkB) are not only regulated by stress but are also altered in these illnesses. We therefore examined if BDNF/TrkB signalling is altered in the post-mortem brain of teenage suicide victims. Protein and mRNA expression of BDNF and of TrkB receptors were determined in the prefrontal cortex (PFC), Brodmanns Area 9 (BA 9), and hippocampus obtained from 29 teenage suicide victims and 25 matched normal control subjects. Protein expression was determined using the Western blot technique; mRNA levels by a quantitative RT-PCR technique. The protein expression of BDNF was significantly decreased in the PFC of teenage suicide victims compared with normal control subjects, whereas no change was observed in the hippocampus. Protein expression of TrkB full-length receptors was significantly decreased in both PFC and hippocampus of teenage suicide victims without any significant changes in the truncated form of TrkB receptors. mRNA expression of both BDNF and TrkB was significantly decreased in the PFC and hippocampus of teenage suicide victims compared with normal control subjects. These studies indicate a down-regulation of both BDNF and its receptor TrkB in the PFC and hippocampus of teenage suicide victims, which suggests that stress and altered BDNF may represent a major vulnerability factor in teenage suicidal behaviour.

Selective deficits in erythrocyte docosahexaenoic acid composition in adult patients with bipolar disorder and major depressive disorder

BACKGROUND Epidemiological and controlled intervention trials suggest that omega-3 (n-3) fatty acid deficiency represents a reversible risk factor for recurrent affective disorders. However, there is limited comparative information available regarding the n-3 fatty acid status and associated mood symptoms in medication-free patients with major depressive disorder (MDD) and bipolar disorder (BD). METHODS The fatty acid composition of erythrocyte membranes from adult male and female healthy controls (n=20) and medication-free patients with MDD (n=20) and BD (n=20) was determined by gas chromatography. Associations with depression and mania symptom severity scores were investigated. RESULTS After correction for multiple comparisons, both MDD (-20%) and BD (-32%) patients exhibited significantly lower erythrocyte docosahexaenoic acid (DHA, 22:6n-3) composition relative to healthy controls, and there was a trend for lower DHA in BD patients relative to MDD patients (-15%, p=0.09). There were no gender differences for DHA in any group. Other n-3 fatty acids, including eicosapentaenoic acid (EPA, 20:5n-3) and docosapentanoic acid (22:5n-3), and n-6 fatty acids, including arachidonic acid (AA, 20:4n-6), were not different. Erythrocyte DHA composition was inversely correlated with indices of delta-9 desaturase activity (18:1/18:0), and associated elevations in oleic acid (18:1n-9) composition, and delta-6 desaturase activity (20:3/18:2). DHA composition was not significantly correlated with depression or mania symptom severity scores. LIMITATIONS Data regarding diet and life style factors (cigarette smoking) were not available to evaluate their contribution to the present findings. CONCLUSIONS Male and female patients with MDD and BD exhibit selective erythrocyte DHA deficits relative to healthy controls, and this deficit was numerically greater in BD patients. Selective DHA deficits are consistent with impaired peroxisome function, which has implications for n-3 fatty acid interventions aimed at preventing or reversing this deficit.

NEUROENDOCRINE AND AMINE STUDIES IN AFFECTIVE ILLNESS

SUMMARY (1) There are limitations to some of these studies because of the small number of patients involved, but our data suggest that maximal Growth Hormone (GH) levels after induced hypoglycemia were lower in depressed patients than in control subjects. (2) Manic patients showed low GH peaks during the Insulin Tolerance Test (ITT), and furthermore urinary 3-methoxy-4-hydroxyphenylene glycol (MHPG) excretion rates in mania were indistinguishable from normals but higher than in depressed patients. (3) The apomorphine-induced GH response was essentially normal in affective disorder patients, while acute schizophrenic patients showed hypersensitivity of postsynaptic dopamine receptors. (4) Confirming previous studies by Maas et aL (1968, 1972), patients with depressive illness were found to have siguicantly lower urinary MHPG excretion, whereas borderline patients with depressive symptomatology had MHPG values similar to control subjects.

Platelet monoamine oxidase in alcoholism

We studied platelet monamine oxidase (MAO) activity using 14C-tyramine as substrate in hospitalized alcoholic patients in the early phases of abstinence and in nonhospitalized normal control volunteers. Platelet MAO was determined in 75 patients (67 men, 8 women) with alcoholism and 123 normal control volunteers (52 men, 71 women). The platelet MAO activity in alcoholic patients was significantly lower than in normal control volunteers. We also observed that the mean platelet MAO activity in male alcoholics was significantly lower than in normal males. The analysis of platelet MAO in alcoholics revealed a mixture of two normal distributions. Alcoholic patients falling into the low MAO component were younger in age, with a lower age of onset of alcoholism, and had higher frequencies of family history of alcoholism. They thus resembled type II alcoholics described by other investigators. Platelet MAO may thus serve as a useful biological marker for subtyping alcoholism and identifying high-risk groups at an early stage. The findings of this study are consistent with previous reports of low platelet MAO activity in alcoholic patients.

Protein kinase a in postmortem brain of depressed suicide victims: Altered expression of specific regulatory and catalytic subunits

BACKGROUND We recently reported reduced [3H]cyclic adenosine monophosphate binding and catalytic activity of protein kinase A in prefrontal cortex of depressed suicide victims. Here we examined the molecular basis of these alterations and whether these findings can be replicated in another cohort. METHODS Prefrontal cortex from depressed suicide victims and nonpsychiatric controls were obtained from the Lenhossek Human Brain Program, Budapest and the Maryland Brain Collection Program. [3H]cyclic adenosine monophosphate binding and protein kinase A activity were determined by radioligand binding and enzymatic assay, respectively. Expression of catalytic and regulatory subunits was determined by quantitative reverse transcription polymerase chain reaction and Western blot, respectively. RESULTS [3H]cyclic adenosine monophosphate binding and total and endogenous protein kinase A activity were significantly decreased in membrane and cytosol fractions of prefrontal cortex of depressed suicide victims from the Budapest cohort, with a similar magnitude (33%-40% reduction) as reported for the Maryland cohort. In both cohorts, selective reduction (36%-41%) in mRNA and protein expression of the regulatory RIIbeta and the catalytic Cbeta was observed. CONCLUSIONS Our results suggest abnormalities in [3H]cyclic adenosine monophosphate binding and catalytic activity kinase A in brain of depressed suicide victims, which could be due to reduced expression of RIIbeta and Cbeta. These abnormalities in PKA may be critical in the pathophysiology of depression.

Protein kinase C in the postmortem brain of teenage suicide victims

Increased serotonin2A (5-HT2A) receptors have been reported in the postmortem brain of suicide victims. To examine if this increase is associated with the dysregulation of postreceptor sites in the signaling cascade, we determined [3H]phorbol dibutyrate (PDBU) binding to protein kinase C (PKC) in postmortem brain samples (Brodmanns areas 8 and 9) obtained from teenage suicide victims and control subjects. [3H]PDBU binding to PKC was determined in membranal and cytosolic fractions. We observed that Bmax of [3H]PDBU binding sites was significantly decreased in both membranal and cytosolic fractions in brain samples from Brodmanns areas 8-9 compared to matched controls. These results thus suggest that PKC may play a role in the pathophysiology of suicidal behavior.

Neurotrophin Receptor Activation and Expression in Human Postmortem Brain: Effect of Suicide

BACKGROUND The physiological functions of neurotrophins occur through binding to two receptors: pan75 neurotrophin receptor (p75(NTR)) and a family of tropomyosin receptor kinases (Trks A, B, and C). We recently reported that expression of neurotrophins and TrkB were reduced in brains of suicide subjects. This study examines whether expression and activation of Trk receptors and expression of p75(NTR) are altered in brain of these subjects. METHODS Expression levels of TrkA, B, C, and of p75(NTR) were measured by quantitative reverse transcription polymerase chain reaction and Western blot in prefrontal cortex (PFC) and hippocampus of suicide and normal control subjects. The activation of Trks was determined by immunoprecipitation followed by Western blotting using phosphotyrosine antibody. RESULTS In hippocampus, lower mRNA levels of TrkA and TrkC were observed in suicide subjects. In the PFC, the mRNA level of TrkA was decreased, without any change in TrkC. However, the mRNA level of p75(NTR) was increased in both PFC and hippocampus. Immunolabeling studies showed similar results as observed for the mRNAs. In addition, phosphorylation of all Trks was decreased in hippocampus, but in PFC, decreased phosphorylation was noted only for TrkA and B. Increased expression ratios of p75(NTR) to Trks were also observed in PFC and hippocampus of suicide subjects. CONCLUSIONS Our results suggest not only reduced functioning of Trks in brains of suicide subjects but also that increased ratios of p75(NTR) to Trks indicate possible activation of pathways that are apoptotic in nature. These findings may be crucial in the pathophysiology of suicide.