Effects of pregnancy and delivery on serum prolyl endopeptidase (PEP) activity: alterations in serum PEP are related to increased anxiety in the early puerperium and to postpartum depression

Deficiency of prolyl oligopeptidase in mice disturbs synaptic plasticity and reduces anxiety-like behaviour, body weight, and brain volume

Prolyl oligopeptidase (PREP) has been implicated in neurodegeneration and neuroinflammation and has been considered a drug target to enhance memory in dementia. However, the true physiological role of PREP is not yet understood. In this paper, we report the phenotyping of a mouse line where the PREP gene has been knocked out. This work indicates that the lack of PREP in mice causes reduced anxiety but also hyperactivity. The cortical volumes of PREP knockout mice were smaller than those of wild type littermates. Additionally, we found increased expression of diazepam binding inhibitor protein in the cortex and of the somatostatin receptor-2 in the hippocampus of PREP knockout mice. Furthermore, immunohistochemistry and tail suspension test revealed lack of response of PREP knockout mice to lipopolysaccharide insult. Further analysis revealed significantly increased levels of polysialylated-neural cell adhesion molecule in PREP deficient mice. These findings might be explained as possible alteration in brain plasticity caused by PREP deficiency, which in turn affect behaviour and brain development.

Lower Serum Zinc and Higher CRP Strongly Predict Prenatal Depression and Physio-somatic Symptoms, Which All Together Predict Postnatal Depressive Symptoms

Pregnancy and delivery are associated with activation of immune-inflammatory pathways which may prime parturients to develop postnatal depression. There are, however, few data on the associations between immune-inflammatory pathways and prenatal depression and physio-somatic symptoms. This study examined the associations between serum zinc, C-reactive protein (CRP), and haptoglobin at the end of term and prenatal physio-somatic symptoms (fatigue, back pain, muscle pain, dyspepsia, obstipation) and prenatal and postnatal depressive and anxiety symptoms as measured using the Edinburgh Postnatal Depression Scale (EPDS), Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HAMD), and Spielberger's State Anxiety Inventory (STAI). Zinc and haptoglobin were significantly lower and CRP increased at the end of term as compared with non-pregnant women. Prenatal depression was predicted by lower zinc and lifetime history of depression, anxiety, and premenstrual tension syndrome (PMS). The latter histories were also significantly and inversely related to lower zinc. The severity of prenatal EDPS, HAMD, BDI, STAI, and physio-somatic symptoms was predicted by fatigue in the first and second trimesters, a positive life history of depression, anxiety, and PMS, and lower zinc and higher CRP. Postnatal depressive symptoms are predicted by prenatal depression, physio-somatic symptoms, zinc and CRP. Prenatal depressive and physio-somatic symptoms have an immune-inflammatory pathophysiology, while postnatal depressive symptoms are highly predicted by prenatal immune activation, prenatal depression, and a lifetime history of depression and PMS. Previous episodes of depression, anxiety disorders, and PMS may prime pregnant females to develop prenatal and postnatal depressive symptoms via activated immune pathways.

Regulation of anxiety during the postpartum period

Healthy mother-infant interactions are critical for the physical, cognitive, and psychological development of offspring. Such interactions rely on numerous factors, including a positive maternal emotional state. However, many postpartum women experience emotional dysregulation, often involving elevated anxiety. Neuroendocrine factors contributing to the onset of postpartum anxiety symptoms are mostly unknown, but irregularities in hypothalamic-pituitary-adrenal axis function, reduced prolactin and oxytocin signaling, or parturitional withdrawal of ovarian, placental and neural steroids could contribute to anxiety in susceptible women. Although the causes of initial onset are unclear, postpartum anxiety can be mitigated by recent contact with infants. Numerous neurochemical systems, including oxytocin, prolactin, GABA, and norepinephrine mediate this anxiolytic effect of infant contact. Insight into the etiology of postpartum anxiety disorders, and how contact with infants helps counter existing anxiety dysregulation, will surely facilitate the diagnosis and treatment of postpartum women at risk for, or experiencing, an anxiety disorder.

Interferon-induced depression in chronic hepatitis C: a review of its prevalence, risk factors, biology, and treatment approaches

Hepatitis C viral infection is a global health problem that affects approximately 4 million people in the United States. Combination treatment with pegylated interferon (IFN)-alpha plus ribavirin has been shown to be most effective in treating patients with chronic hepatitis C (CHC). Despite its efficacy, one of the most common side effects of this regimen is depression. Whereas IFN-alpha has been found to induce depression in chronic myelogenous leukemia, melanoma, and renal cell carcinoma, CHC patients may be especially prone to develop IFN-induced depression. This review includes a summary of differences between IFN-alpha and IFN-beta and addresses whether pegylation of IFN (versus nonpegylated IFN) gives rise to a treatment with reduced potential to induce depressive symptoms. Consideration is also given to evidence showing that treatment with ribavirin may contribute to IFN-induced depression. Thyroid disorders and anemia (as well as other medical conditions) have also been associated with IFN exposure and may account for some incidences of depression in CHC patients. Evidence is reviewed indicating that prior psychiatric and mood disorders (especially previous episodes of major depressive disorder), just prior to IFN treatment, contribute to the propensity to develop depression during treatment. In addition, a brief description is provided of potential biological mechanisms of IFN-induced depression (ie, monoamines, hypothalamic-pituitary-adrenocortical [HPA] axis, proinflammatory cytokines, peptidases, intercellular adhesion molecule-1, and nitric oxide). Finally, a discussion is provided on the use of antidepressants as a preventative versus restorative treatment, including a commentary on risks of using antidepressants in this patient population.

Two peptidase activities decrease in treated bipolar disorder not schizophrenic patients

BACKGROUND

Inhibition of prolyl oligopeptidase (PO) in primary neuronal cultures has been shown to reverse the effect of the common mood-stabilizers lithium, valproic acid and carbamazepine. In clinical studies, abnormal plasma PO activity has been associated with bipolar disorder (BD) and schizophrenia. However, this association is complicated by the discovery in bovine plasma of a Z-Pro-prolinal-insensitive peptidase (ZIP), a novel enzyme that cleaves the same substrate as PO.

METHODS

We developed an assay to distinguish between ZIP and PO and measured both activities in plasma from 48 BD and 50 schizophrenic patients undergoing treatment and compared them with 50 control subjects.

RESULTS

ZIP activity is restricted to blood plasma, whereas PO activity is present in the cytosol of lymphocytes, but can also be detected in blood plasma. Significant decreases in their plasma activities were found between treated BD (p = 0.007 and 0.03 respectively) but not schizophrenic (p > 0.05) patients and controls.

CONCLUSIONS

We have found that the enzyme activity previously reported as plasma PO actually comprises two enzymes, PO and ZIP. This study shows a statistically significant decrease of both enzymes in BD patients undergoing lithium treatment. No statistically significant change in PO or ZIP activity is observed in schizophrenic patients.

Lower activities of serum peptidases predict higher depressive and anxiety levels following interferon-alpha-based immunotherapy in patients with hepatitis C

OBJECTIVE

There is evidence that in patients with chronic hepatitis C, immunotherapy with interferon-alpha (IFN alpha) may induce depression. A lowered activity of peptidases, such as prolylendopeptidase (PEP) and dipeptidyl peptidase IV (DPP IV), occurs in depression. This study examines whether lowered serum PEP or DPP IV activity before starting IFN alpha-based immunotherapy predicts the increase in depressive symptoms during immunotherapy.

METHOD

Serum PEP and DPP IV activities are measured in patients with hepatitis C before and 2, 4 and 16 weeks after starting IFN alpha-based immunotherapy. The Montgomery Asberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A) are completed.

RESULTS

Patients with lower baseline PEP or DPP IV had significantly higher MADRS and HAM-A scores both at baseline and during immunotherapy. Patients with lower baseline DPP IV had significantly higher increases in the MADRS following IFN alpha treatment.

CONCLUSION

Lower baseline PEP and DPP IV predict higher depressive and anxiety ratings during IFN alpha-based immunotherapy.