Low levels of MHPG in depressive spectrum patients

Low baseline salivary 3-methoxy-4-hydroxyphenylglycol (MHPG) in drug-naïve patients with short-illness-duration first episode major depressive disorder

BACKGROUND

Central noradrenergic dysfunction with autonomic nervous system dysregulation are reported in major depressive disorder (MDD). Salivary 3-methoxy-4-hydroxyphenylglycol (sMHPG) is indicative of central noradrenergic activity. Studies on MHPG in bodily fluids are inconsistent and scarce data is available regarding baseline sMHPG concentration in MDD.

METHODS

The basal, non-stimulated sMHPG concentration was studied in this cross-sectional case-control study on 20 non-late-life adult, short-illness-duration first-episode, treatment-naïve MDD patients and in 20 age- and sex-matched healthy controls. Depressed patients showed a score in the Hamilton rating scale for depression (HAMD-17) higher than 20.

RESULTS

The baseline sMHPG concentration was significantly lower in depressed individuals as compared to controls (p=0.025). In post hoc analysis significantly lower sMHPG was present in melancholic MDD (p=0.009) as related to controls whereas no difference was seen between non-melancholic MDD patients and controls. The concentration of sMHPG was not significantly correlated neither with duration nor the severity of depressive symptoms as measured by the total HAMD-17 score.

LIMITATIONS

The current study is limited by its cross-sectional design and small sample size.

CONCLUSION

Low baseline sMHPG concentration was found in MDD. The study provides no support for elevated sMHPG in drug-naïve patients with short-illness-duration first episode MDD. Taken into account the physiology of sMHPG secretion the study results corroborate with the evidence for decreased central noradrenergic activity in MDD when sMHPG is considered indicative of central noradrenergic function.

N-Acetyl cysteine reverses social isolation rearing induced changes in cortico-striatal monoamines in rats

Schizophrenia is causally associated with early-life environmental stress, implicating oxidative stress in its pathophysiology. N-acetyl cysteine (NAC), a glutathione precursor and antioxidant, is emerging as a useful agent in the adjunctive treatment of schizophrenia and other psychiatric illnesses. However, its actions on brain monoamine metabolism are unknown. Social isolation rearing (SIR) in rats presents with face, predictive and construct validity for schizophrenia. This study evaluated the dose-dependent effects of NAC (50, 150 and 250 mg/kg/day × 14 days) on SIR- vs. socially reared induced changes in cortico-striatal levels of dopamine (DA), serotonin (5-HT) noradrenaline (NA) and their associated metabolites. SIR induced significant deficits in frontal cortical DA and its metabolites, 3,4-dihydroxyphenylacetic acid (Dopac) and homovanillic acid (HVA), reduced 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), and reduced levels of the NA metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG). In addition, significant elevations in frontal cortical NA and striatal DA, Dopac, HVA, 5-HT, 5-HIAA, NA and MHPG were also observed in SIR rats. NAC at 150 and 250 mg/kg reversed all cortico-striatal DA, Dopac, HVA, 5-HT, 5-HIAA and striatal NA alterations in SIR animals, with 250 mg/kg of NAC also reversing alterations in cortico-striatal MHPG. In conclusion, SIR profoundly alters cortico-striatal DA, 5-HT and NA pathways that parallel observations in schizophrenia, while these changes are dose-dependently reversed or abrogated by sub-chronic NAC treatment. A modulatory action on cortico-striatal monoamines may explain NACs' therapeutic use in schizophrenia and possibly other psychiatric disorders, where redox dysfunction or oxidative stress is a causal factor.

Cortisol in violent suicidal behaviour: association with personality and monoaminergic activity

BACKGROUND

According to recent theories, suicidal behaviour is associated with depressive disorders that are commonly induced by social stressors in persons with a trait-dependent vulnerability. Stressor-induced increased cortisol secretion may interfere with this vulnerability that can be defined in terms of (possibly inter-related) biological and psychological or personality-related characteristics. Delineation of such trait-like characteristics may increase the specificity in the prediction of suicidal behaviour and thus lead to new approaches to the treatment and prevention of suicidal behaviour.

METHODS

Psychiatric symptomatology, personality dimensions (Cloninger's Temperament and Character), peripheral markers of serotonergic (whole blood serotonin, platelet MAO activity) and noradrenergic (plasma MHPG) activity, and urinary cortisol were measured in a random sample of patients with a history of violent suicidal behaviour and compared to those of patients without such a history.

RESULTS

When compared to patients without a history of violent suicidal behaviour (n=23), patients with such a history (n=17) were characterised by higher urinary cortisol levels, a significantly lower mean score on Reward Dependence, a borderline significantly increased score on Novelty Seeking and a significantly lower mean plasma MHPG level. Urinary cortisol level correlated significantly with Reward Dependence and Novelty Seeking scores. There were no differences between patient groups regarding severity of anxiety or depressive symptomatology. No differences with regard to the biological parameters were found between patients who recently attempted suicide and those with a history of suicidal behaviour.

LIMITATIONS

Limitations of this study included a relatively small number of study subjects and the use of peripheral markers to assess central neurotransmission functions.

CONCLUSIONS

Violent suicidal behaviour is associated with increased cortisol secretion, a personality profile defined by low Reward Dependence (reflecting the degree of sensitivity to social stressors) and a tendency of increased Novelty Seeking (related to impulsivity and the regulation of anger), and reduced noradrenergic functioning (possibly reflecting an inability to adapt to stressors).

Urinary levels of 3-methoxy-4-hydroxyphenylglycol predict symptom severity in selected patients with unipolar depression

There are preliminary biological data that support the validity of subtyping depressed patients by family history into depressive spectrum disease (DSD) and non-DSD groups. We hypothesized that a relatively homogeneous group of depressed patients might show an association between symptom severity and the norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG). Twenty-four patients with non-DSD depression showed a relationship between urinary levels of MHPG and the severity of several depressive symptoms. There were no associations between MHPG and symptom severity for 38 DSD patients. This study provides additional support for the validity of family history approaches to subtyping depression. The data also suggest that norepinephrine may be involved in some way in the pathogenesis of symptoms in non-DSD depression.