Alzheimer's disease (AD) is one of the most devastating diseases currently in the world with no effective treatments. There is increasing evidence that the gut microbiome plays a role in AD. Here we set out to study the age-related changes in the microbiome of the Tgf344-AD rats. We performed 16S ribosomal RNA sequencing on the fecal samples of male rats at 14 and 20 months of age. We found the Tgf344-AD rats to have decreased microbial diversity compared to controls at 14 months of age and this was found to be opposite at 20 months of age. Interestingly, we found a distinctive shift in the microbial community structure of the rats with aging along with changes in the microbiota composition. Some of the observed changes in the Tgf344AD rats were in the genera Bifidobacterium, Ruminococcus, Parasutterella, Lachnoclostridium and Butyricicoccus. Other age-related changes occuring in both the Tgf344-AD and WT control rats were decreases in Enterohaldus, Escherichia Shigella, Rothia and increase in Turicibacter and Clostrium_senso_stricto. Our study has shown that gut microbiota changes occurs in this Alzheimer's disease rat model.www.aging-us.com AGINGC. difficile infection [12]. These studies posit a view that gut microbiome modulation could be a potential therapy for treating AD.

Alzheimer's disease (AD) is a growing public health concern in both the United States and the world. For Americans aged 65 or older, AD represents the fifth leading cause of death ("2020 Alzheimer's disease facts and figures," 2020), and it is estimated that over 80 million people worldwide will be living with some form of dementia by 2040 with AD comprising a majority of these (Ballard et al., 2011).AD is broadly characterized by an irreversible progressive loss of cognition and memory often accompanied by anxiety-like behavior

Growth hormone (GH) signaling plays a key role in mediating growth, development, metabolism, and lifespan regulation. However, the mechanisms of longevity regulation at the cellular and molecular level are still not well-understood. An important area in the field of GH research is in the development of advanced transgenic systems for conditional expression of GH signaling in a cell type- or tissue-specific manner. There have been many recent studies conducted to examine the effects of tissue-specific GHR disruption. This review updates our previous discussions on this topic and summarizes recent data on the newly-made tissue-specific GHR-KO mice including intestinal epithelial cells, bone, hematopoietic stem cells, cardiac myocytes, and specific brain regions. The data from these new genetically-engineered mice have a significant impact on our understanding of the local GH signaling function.