Density of dopaminergic fibres in the prefrontal cortex of gerbils is sensitive to aging

Brummelte S, Teuchert-Noodt G. Density of dopaminergic fibres in the prefrontal cortex of gerbils is sensitive to aging. Behavioral and Brain Functions. 2007;3(1): 14.Mesencephalic dopamine (DA) projections are essential for cognitive and behavioral functions and believed to play a critical role during development and aging. The dopaminergic afferents of the rodent prefrontal cortex (PFC) show an extremely prolonged maturation which is very sensitive to epigenetic challenges. However, less is known about the long-term maturation and aging of these DA axons. Therefore, immunohistochemically stained DA fibres were quantitatively examined in the PFC of the Mongolian gerbil (Meriones unguiculatus) ranging from 6 to 24 months of age. Results show a decrease in DA fibre densities in the superficial layers of the PFC in 24 month old animals compared to 6 and 12 months

Resilience priming: translational models for understanding resiliency and adaptation to early life adversity

Despite the increasing attention to early life adversity and its long-term consequences on health, behavior, and the etiology of neurodevelopmental disorders, our understanding of the adaptations and interventions that promote resiliency and rescue against such insults are underexplored. Specifically, investigations of the perinatal period often focus on negative events/outcomes. In contrast, positive experiences (i.e. enrichment/parental care//healthy nutrition) favorably influence development of the nervous and endocrine systems. Moreover, some stressors result in adaptations and demonstrations of later-life resiliency. This review explores the underlying mechanisms of neuroplasticity that follow some of these early life experiences and translates them into ideas for interventions in pediatric settings. The emerging role of the gut microbiome in mediating stress susceptibility is also discussed. Since many negative outcomes of early experiences are known, it is time to identify mechanisms and mediators that promote resiliency against them. These range from enrichment, quality parental care, dietary interventions and those that target the gut microbiota

Environmental enrichment has no effect on the development of dopaminergic and GABAergic fibers during methylphenidate treatment of early traumatized gerbils

It is widely believed, that environmental factors play a crucial role in the etiology and outcome of psychiatric diseases such as Attention-Deficit/Hyperactivity Disorder (ADHD). A former study from our laboratory has shown that both methylphenidate (MP) and handling have a positive effect on the dopaminergic fiber density in the prefrontal cortex (PFC) of early traumatized gerbils (Meriones unguiculatus). The current study was performed to investigate if enriched environment during MP application has an additional influence on the dopaminergic and GABAergic fiber densities in the PFC and amygdala in this animal model

Postnatal development of dopamine innervation in the amygdala and the entorhinal cortex of the gerbil (Meriones unguiculatus)

Brummelte S, Teuchert-Noodt G. Postnatal development of dopamine innervation in the amygdala and the entorhinal cortex of the gerbil (Meriones unguiculatus). BRAIN RESEARCH. 2006;1125(1):9-16.Dopamine (DA) projections from the mesencephalon are believed to play a critical role during development and are essential for cognitive and behavioral functions. Since the postnatal maturation patterns of these projections differ substantially between various brain regions, cortical, limbic or subcortical areas might exhibit varying vulnerabilities concerning developmental disorders. The dopaminergic afferents of the rodent prefrontal cortex show an extremely prolonged maturation which is very sensitive to epigenetic challenges. However, less is known about the development of the DA innervation of caudal limbic areas. Therefore, immunohistochemically stained DA fibers were quantitatively examined in the basolateral (BLA) and central amygdaloid nucleus (CE) and the ventrolateral entorhinal cortex (EC) of the Mongolian gerbil (Meriones unguiculatus). Animals of different ages, ranging from juvenile [postnatal day (PD) 14, 20, 30)] to adolescent (PD70), adult (6, 18 months) and aged (24 months), were analyzed. Results show a significant increase of fibers between PD14 and PD20 in the BLA and lateral part of the CE, with a trend for a subsequent decline in fiber densities until PD30. The EC and medial part of the CE showed no developmental changes. Interestingly, none of the investigated areas showed significant reductions of DA fibers during aging. (c) 2006 Elsevier B.V. All rights reserved

Chronic corticosterone during pregnancy and postpartum affects maternal care, cell proliferation and depressive-like behavior in the dam

Stress during pregnancy and the postpartum can influence the well-being of both the mother and her offspring. Prolonged elevated levels of glucocorticoids are associated with depression and we developed an animal model of postpartum depression/stress based on high levels of corticosterone (CORT) during the postpartum. Gestational stress is a risk factor for postpartum depression and prenatal and/or postnatal high levels of CORT may have differential effects on the mother. Thus the present study was conducted to investigate the effects of low (10mg/kg) or high levels of CORT (40mg/kg) given to dams either during gestation, postpartum or across both gestation and postpartum on maternal care, depressive-like behavior and hippocampal cell proliferation in the dam. Only the high dose of CORT administered during the postpartum increased depressive-like behavior in the dam. Furthermore the high dose of CORT altered maternal care (reduced time spent on the nest and nursing) regardless of whether administration of CORT was during gestation or postpartum. Gestational and/or postpartum treatment with high CORT and postpartum low CORT reduced cell proliferation in the dentate gyrus of postpartum dams compared to oil-treated controls. Thus prolonged treatment with high levels of CORT postpartum reduced maternal care, hippocampal cell proliferation and induced depressive-like behavior in the dam and therefore might be considered an animal model of postpartum depression. More research is needed to understand the effects of stress hormones during different phases of reproduction and how they affect the brain and behavior of the mother and her offspring.Arts, Faculty ofPsychology, Department ofReviewedFacultyPostdoctora

Postnatal development of GABA and calbindin cells and fibers in the prefrontal cortex and basolateral amygdala of gerbils (Meriones unguiculatus)

Brummelte S, Witte V, Teuchert-Noodt G. Postnatal development of GABA and calbindin cells and fibers in the prefrontal cortex and basolateral amygdala of gerbils (Meriones unguiculatus). International Journal of Developmental Neuroscience. 2007;25(3):191-200.The postnatal maturation of immunohistochemically stained gamma-amino-butyric acid (GABA) and calbindin (CB) cells and fibers were quantitatively examined in the prefrontal cortex (PFC) and the basolateral amygdala (BLA) of the Mongolian gerbil (Meriones unguiculatus). Animals of different ages, ranging from juvenile (postnatal day (PD)14, PD20, PD30), to adolescent (PD70), adult (PD180, PD540) and aged (PD720) were analyzed. Results reveal an increase in GABAergic fiber densities between PD14-20 in the PFC and the BLA with a concomitant decrease in cell density. After PD70 GABA fiber density slightly decreases again in the BLA, while there is a further slow but significant increase in the PFC between PD70 and PD540. Fibers immunoreactive for the calcium binding-protein CB, which is predominantly localized in particular GABAergic subpopulations, also accumulate between PD14 and PD20 in the PFC and BLA, while a concomitant decrease in cell density is only seen in the BLA. Both areas reveal a decrease of CB cells between PD30 and PD70, which parallels with a decrease of CB fibers in the PFC. However, there is no particular 'aging-effect' in the fiber or cell densities of GABA or CB in any of the investigated areas in old animals. In conclusion, we here demonstrate long-term dynamics in cell and fiber densities of the GABAergic system until late in development which might correspond to the prolonged maturation of other neuroanatomical and functional systems. (C) 2007 ISDN. Published by Elsevier Ltd. All rights reserved

Effect of postnatal methamphetamine trauma and adolescent methylphenidate treatment on adult hippocampal neurogenesis in gerbils

Schaefers AT, Teuchert-Noodt G, Bagorda F, Brummelte S. Effect of postnatal methamphetamine trauma and adolescent methylphenidate treatment on adult hippocampal neurogenesis in gerbils. European Journal of Pharmacology. 2009;616(1-3):86-90.Methyphenidate (e.g. Ritalin (R)) is the mostcommon drug used in the treatment of attention-deficit hyperactivity disorder. However, only a few studies have investigated the neuroanatomical long-term effects of this treatment. Prolonged application of methylphenidate during adolescence causes alterations in dopaminergic fiber or receptor densities in adult rodents. This study was conducted to investigate the effects of adolescent methylphenidate treatment on adult hippocampal neurogenesis in male gerbils (Meriones unguiculatus). Animals were first treated with either a single methamphetamine challenge on postnatal day 14 (to cause a disturbance in the dopaminergic system, to mimic the disturbed dopaminergic system seen in ADHD children) or saline and then received a daily oral application of 5 mg/kg methylphenidate or water from postnatal day 30-60 or were left undisturbed. On postnatal 90 gerbils were injected with bromodeoxyuridine (BrdU, a DNA synthesis marker) and sacrificed seven days later. Results reveal that the pretreatment with methamphetamine causes a decrease in the number of BrdU-positive cells in the dentate gyrus. Methylphenidate treatment however did not cause any differences in the number of labelled cells in any group. This implies that, despite methylphenidate's efficiency in inducing changes in the dopaminergic system and associated areas, it might be less effective in altering neurogenesis in the hippocampus. (C) 2009 Elsevier B.V. All rights reserved