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Elevated Plus Maze Test Combined with Video Tracking Software to Investigate the Anxiolytic Effect of Exogenous Ketogenic Supplements

The overall goal of this study is to describe the methodology of the elevated plus maze (EPM) test in combination with a video tracking software. The ...

University of South Florida

We previously reported that chronic hyperglycemia, but not hypoglycemia, was associated with the reduction of neuronal size in the rat brain. We hypothesized that hyperglycemia-induced changes in neuronal structure would have negative consequences, such as impaired learning and memory. We therefore assessed the effects of hyperglycemia and hypoglycemia on neuronal dendritic structure and cognitive functioning in young rats.

Hyperglycemia not hypoglycemia alters neuronal dendrites and impairs spatial memory.

We have a well-established animal model of PTSD composed of predator exposure administered in conjunction with social instability that produces PTSD-like behavioral and physiological abnormalities one month after stress initiation. Here, we assessed whether the PTSD-like effects would persist for at least 4months after the initiation of the psychosocial stress regimen. Adult male Sprague-Dawley rats were exposed to either 2 or 3 predator-based fear conditioning sessions. During each session, rats were placed in a chamber for a 3-min period that terminated with a 30-s tone, followed by 1h of immobilization of the rats during cat exposure (Day 1). All rats in the stress groups received a second fear conditioning session 10days later (Day 11). Half of the stress rats received a third fear conditioning session 3weeks later (Day 32). The two cat-exposed groups were also exposed to daily unstable housing conditions for the entire duration of the psychosocial stress regimen. The control group received stable (conventional) housing conditions and an equivalent amount of chamber exposure on Days 1, 11 and 32, without cat exposure. Behavioral testing commenced for all groups on Day 116. The stress groups demonstrated increased anxiety on the elevated plus maze, impaired object recognition memory and robust contextual and cued fear conditioned memory 3months after the last conditioning session. Combined data from the two stress groups revealed lower post-stress corticosterone levels and greater diastolic blood pressure relative to the control group. These findings indicate that predator-based psychosocial stress produces persistent PTSD-like physiological and behavioral abnormalities that may provide insight into the neurobiological and endocrine sequelae in traumatized people with PTSD. 

Psychosocial predator-based animal model of PTSD produces physiological and behavioral sequelae and a traumatic memory four months following stress onset.

Hyperinsulinemia activates brain Akt and PKC-λ/ι and increases Aβ and phospho-tau in insulin-resistant animals. Here, we examined underlying mechanisms in mice, neuronal cells, and mouse hippocampal slices. Like Aβ, β-secretase activity was increased in insulin-resistant mice and monkeys. In insulin-resistant mice, inhibition of hepatic PKC-λ/ι sufficient to correct hepatic abnormalities and hyperinsulinemia simultaneously reversed increases in Akt, atypical protein kinase C (aPKC), β-secretase, and Aβ, and restored acute Akt activation. However, 2 aPKC inhibitors additionally blocked insulin's ability to activate brain PKC-λ/ι and thereby increase β-secretase and Aβ. Furthermore, direct blockade of brain aPKC simultaneously corrected an impairment in novel object recognition in high-fat-fed insulin-resistant mice. In neuronal cells and/or mouse hippocampal slices, PKC-ι/λ activation by insulin, metformin, or expression of constitutive PKC-ι provoked increases in β-secretase, Aβ, and phospho-thr-231-tau that were blocked by various PKC-λ/ι inhibitors, but not by an Akt inhibitor. PKC-λ/ι provokes increases in brain β-secretase, Aβ, and phospho-thr-231-tau. Excessive signaling via PKC-λ/ι may link hyperinsulinemia and other PKC-λ/ι activators to pathological and functional abnormalities in Alzheimer's disease.

Atypical PKC, PKCλ/ι, activates β-secretase and increases Aβ and phospho-tau in mouse brain and isolated neuronal cells, and may link hyperinsulinemia and other aPKC activators to development of pathological and memory abnormalities in Alzheimer's disease.

Article	Year
Hyperglycemia not hypoglycemia alters neuronal dendrites and impairs spatial memory. Pediatric diabetes\| PubMed ID: 19067891	2008
Psychosocial predator-based animal model of PTSD produces physiological and behavioral sequelae and a traumatic memory four months following stress onset. Physiology & behavior\| PubMed ID: 25911267	2015
Atypical PKC, PKCλ/ι, activates β-secretase and increases Aβ and phospho-tau in mouse brain and isolated neuronal cells, and may link hyperinsulinemia and other aPKC activators to developmen... Neurobiology of aging\| PubMed ID: 29032894	2018

Collin Park

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