Browsing by Subject "Sexual dimorphism"

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Open Access
Age and gender alter synaptic proteins in zebrafish (Danio Rerio) models of normal and delayed aging
(2017-07) Karoğlu, Elif Tuğçe
Cognitive decline occurs during normal aging in some specific domains of cognitive abilities including but not limited to episodic memory, divided attention and executive functions, however, it is not a unitary decline since some cognitive domains, including vocabulary and implicit memory tend to be preserved and even improved at older ages. Normal aging is not associated with global and significant neuronal and synapse loss, yet subtle molecular alterations occurring in gene expression patterns, protein homeostasis, mitochondrial dynamics and hypofunction in the cholinergic system may account for the age related decline in some cognitive abilities. Additionally, males and females showed differential vulnerabilities against age-related alterations in the cognitive abilities, physiological integrity and subtle molecular dynamics. More direct relationships can be established between the age-related cognitive decline and subtle molecular changes by analyzing the elements of synaptic integrity, which could alter synaptic plasticity and result in the changes in learning and memory abilities. Post-synaptic 95 (PSD-95), gephyrin (GEP) and synaptophysin (SYP) are integral synaptic proteins and they could be attributed as indicators of excitatory post-synaptic, inhibitory post-synaptic and pre-synaptic integrities, respectively. The first aim of this study was to show effects of age and gender on the expression levels of PSD-95, GEP and SYP in young, middle-aged and old, female and male zebrafish cohorts. Significant age by gender interactions were revealed in the levels of PSD-95 and SYP. It was shown that PSD-95 and SYP levels tend to be preserved and increased in the female groups throughout the aging process, whereas, in male groups, expression levels of these proteins tend to be reduced at older ages. The second aim was to investigate whether ameliorating the cholinergic hypofunction might have beneficial effects on the aging-related protein expression alterations and check for sexually dimorphic patterns. For this aim old male and female zebrafish from a mutant line (ache), which has decreased levels of acetylcholinesterase and increased levels of acetylcholine, were compared with old male and female wildtype animals. In the ache old groups, significant increases in the expression levels of SYP and GEP were revealed compared to the wildtype, and also in the old ache females SYP expression was higher than the other groups. These studies emphasized the importance of gender and sexually dimorphic patterns in the context of aging andcholinergic manipulations could be a promising target of intervention to attenuate the effects of age-related synaptic alterations, which could have possible contributions to age-related cognitive decline. .
Open Access
Environmental enrichment applied with sensory components prevents age-related decline in synaptic dynamics: Evidence from the zebrafish model organism
(Elsevier BV, 2021-07-01) Eravşar, Elif Tuğçe Karoğlu; Sasık, Melek Umay Tuz; Adams, Michelle M.
Progression of cognitive decline with or without neurodegeneration varies among elderly subjects. The main aim of the current study was to illuminate the molecular mechanisms that promote and retain successful aging in the context of factors such as environment and gender, both of which alter the resilience of the aging brain. Environmental enrichment (EE) is one intervention that may lead to the maintenance of cognitive processing at older ages in both humans and animal subjects. EE is easily applied to different model organisms, including zebrafish, which show similar age-related molecular and behavioral changes as humans. Global changes in cellular and synaptic markers with respect to age, gender and 4-weeks of EE applied with sensory stimulation were investigated using the zebrafish model organism. Results indicated that EE increases brain weight in an age-dependent manner without affecting general body parameters like body mass index (BMI). Age-related declines in the presynaptic protein synaptophysin, AMPA-type glutamate receptor subunits and a post-mitotic neuronal marker were observed and short-term EE prevents these changes in aged animals, as well as elevates levels of the inhibitory scaffolding protein, gephyrin. Gender-driven alterations were observed in the levels of the glutamate receptor subunits. Oxidative stress markers were significantly increased in the old animals, while exposure to EE did not alter this pattern. These data suggest that EE with sensory stimulation exerts its effects mainly on age-related changes in synaptic dynamics, which likely increase brain resilience through specific cellular mechanisms.
Open Access
Expression of key synaptic proteins in Zebrafish (Danio Rerio) brain following caloric restriction and its mimetic and their relationship with gender
(2017-01) Dede, Ayşegül
Aging is a progressive decline of physiological functioning and metabolic processes. Among all the organs, the brain seems to be the most vulnerable part of the body to the age-related changes because of the relatively high consumption of oxygen and glucose as compared to other organs. Both structural and cognitive changes occur during the aging process. A great effort has been spent to ameliorate the outcomes occurring within the brain as a result of aging. Caloric restriction (CR) is considered to be the only non-genetic intervention which decreases age-related cognitive decline. Rapamycin (RAP) has become a candidate drug which was shown to mimic the effects of CR by blocking the nutrient-sensing pathway, the mammalian target of Rapamycin, (mTOR) pathway. The first aim of this study was to investigate the expressions of key synaptic proteins; gephyrin, PSD-95 and synaptophysin, which are involved in the synaptic plasticity, after short-term (4 weeks) CR and RAP interventions in young and old, male and female zebrafish. The second aim was to investigate whether the expression of glutamate receptor subunits, NR2B and GluR2/3, display a sexually dimorphic pattern in middle age zebrafish. It was found that there was no significant difference in the expression of key synaptic proteins between the CR and RAP animal groups as compared to the ad libitium (AL) fed group and also no significance was found in the expression of NR2B and GluR2/3 in middle-aged male and female zebrafish. Highlighted studies in this thesis demonstrate that short-term (4 weeks) of CR and RAP treatments were too short to observe an effect in the expression level of gephyrin, synaptophysin, and PSD-95, and in the middle age, expression of NR2B and GluR2/3 did not display sexually dimorphic pattern. Our initial results of key synaptic protein levels indicate that they are stable throughout aging with respect to gender and CR interventions.