Publications by Year: 2018

2018
Gemmel M, Kokras N, Dalla C, Pawluski JL. Perinatal fluoxetine prevents the effect of pre-gestational maternal stress on 5-HT in the PFC, but maternal stress has enduring effects on mPFC synaptic structure in offspring. Neuropharmacology 2018;128:168-180.Abstract
Maternal affective disorders are frequently treated with selective serotonin reuptake inhibitor medications (SSRIs); with up to 10% of women being prescribed these medications during pregnancy. Infant development depends on the early serotonergic environment, which is altered by perinatal SSRIs, raising concern about how these medications affect neural outcomes. While clinical and preclinical research suggests an impact of SSRIs on the developing brain, more research is needed to determine the effects on neuroplasticity, the serotonergic system, and the hypothalamic-pituitary-adrenal axis in neural regions mediating behavior. The current work investigated the effects of the SSRI, fluoxetine, on the serotonergic system in the prefrontal cortex (PFC) during pre-adolescence, and changes to synaptic markers and glucocorticoid receptor density in the cingulate cortex (medial PFC) of pre-adolescent and adult Sprague-Dawley male and female rats. To model aspects of Perinatal Depression and maternal anxiety, pre-gestational maternal stress was used resulting in male and female offspring from 4 groups: 1) control, 2) perinatal fluoxetine exposed, 3) pre-gestational maternal stress exposed, and 4) pre-gestational maternal stress + fluoxetine. Perinatal fluoxetine prevented the effects of maternal stress on 5-HT levels and 5-HT turnover ratio in the PFC of pre-adolescent offspring, particularly in females. However, pre-gestational stress reduced synaptophysin and PSD-95 densities in the cingulate cortex, effects that were more pronounced in males. Interestingly, perinatal fluoxetine exposure reduced GR density in adult males in this same brain area. Together, results show differential effects of perinatal SSRIs and pre-gestational maternal stress on neurodevelopment in the PFC of males and females.
Kafetzopoulos V, Kokras N, Sotiropoulos I, Oliveira JF, Leite-Almeida H, Vasalou A, Sardinha VM, Papadopoulou-Daifoti Z, Almeida OFX, Antoniou K, Sousa N, Dalla C. The nucleus reuniens: a key node in the neurocircuitry of stress and depression. Mol Psychiatry 2018;23:579-586.Abstract
The hippocampus and prefrontal cortex (PFC) are connected in a reciprocal manner: whereas the hippocampus projects directly to the PFC, a polysynaptic pathway that passes through the nucleus reuniens (RE) of the thalamus relays inputs from the PFC to the hippocampus. The present study demonstrates that lesioning and/or inactivation of the RE reduces coherence in the PFC-hippocampal pathway, provokes an antidepressant-like behavioral response in the forced swim test and prevents, but does not ameliorate, anhedonia in the chronic mild stress (CMS) model of depression. Additionally, RE lesioning before CMS abrogates the well-known neuromorphological and endocrine correlates of CMS. In summary, this work highlights the importance of the reciprocal connectivity between the hippocampus and PFC in the establishment of stress-induced brain pathology and suggests a role for the RE in promoting resilience to depressive illness.
Karkoula E, Lemonakis N, Kokras N, Dalla C, Gikas E, Skaltsounis AL, Tsarbopoulos A. Trans-crocin 4 is not hydrolyzed to crocetin following i.p. administration in mice, while it shows penetration through the blood brain barrier. Fitoterapia 2018;129:62-72.Abstract
A novel, fit-for-purpose, highly sensitive, analytical UPLC-PDA methodology was developed and fully validated, according to ICH, FDA and EMA guidelines, for the rapid and accurate quantification of trans-crocin 4 (TC4) and crocetin (CRC) in mice plasma and brain after i.p. administration. A PDA based methodology shows a wider applicability as it is cost effective and can be easily and seamlessly adopted by the pharma industry. The separation of the analytes was performed on a C18 Hypersil Gold column with 2.5 min run time, employing the internal standard (ISTD) methodology. The two methods were successfully applied for the determination of CRC and TC4 in mouse plasma and brain after i.p. administration of TC4 (50 mg/kg) in a time range of 0-240 min. Due to the selection of i.p. administration route, the first-pass metabolism and/or gastric hydrolysis were bypassed, a fact that enhanced the bioavailability of TC4. Furthermore, TC4 was found to be capable of crossing the Blood Brain Barrier (BBB) and build up levels in the mouse brain, regardless of its highly hydrophilic character. CRC was not detected in any plasma or brain sample, although it has been reported that TC4 quickly hydrolyzes to CRC after p.o. administration. Therefore i.p. administration could be used in the case of TC4 for the accurate determination of its biological role. Overall, the developed methodology offers important information about the bioavailability of TC4 in mouse plasma and for the first time, demonstrates the ability of TC4 to penetrate the BBB and localize inside the brain.
Kokras N, Pastromas N, Papasava D, de Bournonville C, Cornil CA, Dalla C. Sex differences in behavioral and neurochemical effects of gonadectomy and aromatase inhibition in rats. Psychoneuroendocrinology 2018;87:93-107.Abstract
Aromatase inhibitors, which are widely used for the treatment of estrogen-dependent cancers, have been associated with psychiatric side effects ranging from mania to depression. In the present study, we investigated sex differences in the behavioral and neurochemical effects of aromatase inhibition on male and female, sham-operated or gonadectomized adult rats. Three weeks after surgery, rats received chronic treatment with the aromatase inhibitor letrozole or vehicle and were then subjected to the open field test, which assesses general activity. Half of the subjects were subsequently exposed to the stressful procedure of the forced swim test (FST), which is also a test of antidepressant activity. Aromatase activity was analyzed in the hypothalamus and testosterone and corticosterone were assayed in the blood serum of all rats. The hippocampus and prefrontal cortex (PFC) were analyzed for monoamine (noradrenaline, dopamine and serotonin), as well as amino acid (GABA, glutamate, glycine, taurine, alanine and histidine) levels. The observed decrease in hypothalamic aromatase activity confirmed the efficacy of letrozole treatment in both sexes. Moreover, letrozole enhanced testosterone levels in sham-operated females. In the open field test, females were overall more active and explorative than males and gonadectomy eliminated this sex difference. In the FST, females exhibited overall higher immobility than males and gonadectomy further enhanced this passive behavior in both sexes. However, sustained aromatase inhibition had no effect on open field and FST behaviors. Head shakes during FST, which were fewer in females than in males, were reduced by castration in males and by letrozole treatment in ovariectomized females, suggesting a role of testosterone and extra-gonadal estrogens in the expression of this behavior. Sustained aromatase inhibition also decreased noradrenaline and the dopaminergic turnover rates [DOPAC/DA, HVA/DA] in the hippocampus and PFC of male and female rats, irrespectively of gonadectomy. Moreover, letrozole treatment enhanced the serotonergic turnover [5HIAA/5HT] rate in the hippocampus of males and females, irrespectively of gonadectomy. Amino acid levels were not influenced by letrozole, but sex differences were demonstrated with higher levels in the PFC of females vs. males. Present findings suggest that the neuropsychiatric effects of aromatase inhibition can be attributed to the inhibition of extragonadal estrogen synthesis, presumably in the brain, and could be further associated with serotonergic and catecholaminergic changes in brain regions involved in mood and cognition. Importantly, present data could be linked with the neurobiology of affective side-effects in post-menopausal women receiving aromatase inhibitors.
Kokras N, Stamouli E, Sotiropoulos I, Katirtzoglou EA, Siarkos KT, Dalagiorgou G, Alexandraki KI, Coulocheri S, Piperi C, Politis AM. Acetyl Cholinesterase Inhibitors and Cell-Derived Peripheral Inflammatory Cytokines in Early Stages of Alzheimer's Disease. J Clin Psychopharmacol 2018;38:138-143.Abstract
BACKGROUND: Clinical and preclinical studies firmly support the involvement of the inflammation in the pathogenesis of Alzheimer's disease (AD). Despite acetylcholinesterase inhibitors (AChEI) being widely used in AD patients, there is no conclusive evidence about their impact on the inflammatory response. METHODS: This study investigates peripheral proinflammatory cytokines (interferon gamma [IFN-γ], tumor necrosis factor alpha [TNF-α], and interleukins 1β [IL-1β] and 6 [IL-6]) by firstly comparing peripheral blood mononuclear cell (PBMC)-derived secretion in drug-naïve and AChEI-treated AD patients versus healthy controls. A subset of those drug-naïve AD patients, who were prescribed the AChEI donepezil, was followed-up for 6 months to investigate if donepezil suppresses proinflammatory cell-derived cytokine secretion. RESULTS: Patients with AD showed higher levels of PBMC-derived proinflammatory cytokines (IFN-γ, TNF-α, IL-1β, and IL-6) in comparison with healthy controls. On reexamination, previously drug-naïve AD patients who received donepezil treatment for 6 months displayed a decrease in cell-derived IFN-γ, TNF-α, IL-1β, and IL-6. CONCLUSIONS: Proinflammatory PBMC-derived cytokines were increased in patients with AD in comparison with healthy controls and donepezil-reduced proinflammatory cytokines when examining drug-naïve AD patients before and after AChEI treatment.
Psarros C, Theleritis C, Kokras N, Lyrakos D, Koborozos A, Kakabakou O, Tzanoulinos G, Katsiki P, Bergiannaki JD. Personality characteristics and individual factors associated with PTSD in firefighters one month after extended wildfires. Nord J Psychiatry 2018;72:17-23.Abstract
BACKGROUND: Firefighters participate in activities with intense physical and psychological stress and are constantly at risk to develop various psychopathological reactions. AIMS: To investigate psychological reactions in firefighters one month after devastating wildfires in Greece, during August 2007, which lead to the devastation of large areas and the death of 43 people among whom three were firefighters. METHODS: One month after the wildfires, a joint task force of mental health clinicians was organized in order to provide psychological support and to investigate the psychological consequences of wildfires to firefighters. One hundred and two firefighters, living within the fire-devastated area, who were on duty for the whole period of wildfires were interviewed and assessed with the use of several questionnaires and inventories. RESULTS: Post-traumatic stress disorder (PTSD) was detected in 18.6% of firefighters. Multiple logistic regression found that existence of fear of dying during firefighting, insomnia and increased scores in neuroticism, as well as in depression subscale of the SCL-90, were significantly associated with greater likelihood for having PTSD. Additionally those firefighters who worked permanently had 70% lower probability of having PTSD vs. those seasonally employed. CONCLUSIONS: Insomnia, depressive symptoms, as well as personality characteristics as neuroticism and the perception of fear of imminent death during firefighting operations may precipitate the development of PTSD in firefighters. Within this context, mental health clinicians should be aware that the early detection of these predisposing factors may facilitate the prevention and mitigation of PTSD in firefighters particularly those who are seasonally employed.