DISRUPTION OF HIPPOCAMPAL MEMORY SYSTEMS IN ADULT MICE FOLLOWING FAST NEUTRON IRRADIATION

Аннотация

INTRODUCTION The hippocampus is a critical brain structure Fast neutron irradiation, a type of high-energy involved in the formation, consolidation, and radiation, is of particular interest due to its retrieval of memories. It is particularly essential for biological effects on living organisms. Neutrons are spatial memory and the processing of novel highly penetrating particles that can induce information. Damage to hippocampal circuits can complex molecular damage, leading to cellular lead to cognitive dysfunctions, including injury, oxidative stress, and inflammation. These impairments in both spatial navigation and effects are particularly relevant in the context of recognition memory. Understanding the factors space exploration, where astronauts are exposed to that disrupt hippocampal function is crucial for cosmic radiation, and in cancer treatment, where advancing our knowledge of cognitive diseases and radiation therapies often target rapidly dividing conditions associated with neurological damage. cells but may also impact the brain. While much is One such factor is ionizing radiation, which has known about the general effects of ionizing been shown to negatively affect brain structure and radiation on tissue, the specific impacts of fast function, particularly in the hippocampus. neutron irradiation on hippocampal function and https://www.theamericanjournals.com/index.php/tajvswd 7 THE USA JOURNALS THE AMERICAN JOURNAL OF VETERINARY SCIENCES AND WILDLIFE DISCOVERY (ISSN – 2689-0968) VOLUME 06 ISSUE06 memory processes remain underexplored. radiation was chosen based on previous studies to simulate relevant levels of exposure, with careful In this study, we investigate the effects of fast consideration to avoid lethal doses while inducing neutron irradiation on hippocampal memory measurable cognitive effects. The mice were systems in adult mice. By exposing mice to a anesthetized during irradiation to minimize stress controlled dose of fast neutrons and assessing their and discomfort. The irradiation procedure lasted a performance in spatial and recognition memory short duration, and the animals were allowed to tasks, we aim to understand how radiation recover in a temperature-controlled environment exposure affects hippocampal-dependent memory for 24 hours before undergoing behavioral testing. and neuronal integrity. Additionally, we examine the structural changes in the hippocampus that Behavioral Assessments: To assess the impact of may underlie these cognitive impairments. The fast neutron irradiation on hippocampal- results of this study could provide valuable insights dependent memory, two widely used cognitive into the neurobiological consequences of fast tasks were employed: the Morris water maze neutron exposure and its potential impact on (MWM) and the novel object recognition (NOR) memory and cognitive functions, with broader test. implications for radiation safety in both clinical and Morris Water Maze: The MWM task was used to environmental contexts. evaluate spatial memory and learning ability. In METHODOLOGY this task, each mouse was required to find a hidden platform submerged just below the surface of a This study utilized a controlled experimental pool filled with water. The animals underwent four design to investigate the effects of fast neutron trials per day over a period of 5 consecutive days, irradiation on hippocampal-dependent memory in and the time taken to find the platform (latency) adult mice. The study involved several key steps, was recorded. On day 6, a probe trial was including animal preparation, radiation exposure, conducted to evaluate the memory retention of the behavioral assessments, histological analysis, and platform's location by measuring the time spent in statistical evaluation. All procedures were the target quadrant of the pool. approved by the Institutional Animal Care and Use Committee (IACUC) to ensure ethical standards Novel Object Recognition (NOR): This test was and minimize animal suffering. designed to evaluate recognition memory. Mice were placed in a testing arena and allowed to Animal Preparation: Adult male C57BL/6 mice, explore two identical objects for a period of 10 aged 8-10 weeks, were selected for this study due minutes. After a 24-hour retention interval, one of to their well-documented use in behavioral and the objects was replaced with a novel object. The neurobiological research. Mice were housed in time spent exploring the novel versus familiar standard laboratory conditions with ad libitum object was recorded, and the discrimination index access to food and water, and a 12-hour light/dark (time spent exploring the novel object divided by cycle. Prior to the start of the experiment, the mice total exploration time) was calculated as a measure were acclimatized to the laboratory environment of recognition memory. for at least one week. Mice were randomly assigned to one of two groups: the experimental group Histological Analysis: Af