New links between cholesterol and depression in the elderly

New Links Between Cholesterol and Depression in the Elderly


ScienceDaily (July 21, 2010) — Most people know that high cholesterol levels place them at increased risk for heart disease and stroke. Prior research has shown that particular types of strokes contribute to one's risk for depression, and that abnormal blood lipid levels can increase the risk of depression in the elderly.



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However, new findings by French researchers, published in Biological Psychiatry, suggest the link between increased cholesterol and depression may be complicated. They evaluated a large population of elderly men and women (aged 65 and over) over a seven year follow-up period, assessing them for symptoms of depression and measuring their lipid levels.
They found that, in women, depression was associated with low levels of the "good" form of cholesterol, high density lipoprotein (HDL). This disturbance in their cholesterol levels put them at higher risk for vascular disease, including stroke, by increasing their risk for developing lesions in their blood vessels called atherosclerotic plaques.
In contrast, the men who were at greater risk of depression had low levels of the "bad" form of cholesterol, low density lipoprotein (LDL). This was especially true for those men with a genetic vulnerability to depression related to a serotonin transporter gene.
This finding in men raises important considerations. Although this pattern of low LDL levels seemingly protects them from developing cardiovascular diseases or strokes, this study suggests that it increases their mental health risk at the same time.
Dr. Marie-Laure Ancelin, corresponding author for this study, commented: "Our results suggest that clinical management of abnormal lipid levels may reduce depression in the elderly, but different treatment will be required according to sex. LDL-C serum level seems to be an important biological marker in men, with a narrow range for normal functioning. Above this range, cardio- or cerebro-vascular risk increases and below it, there is increased risk of depression."
Therefore, the authors suggest that properly regulating the levels of HDL and LDL may help to prevent depression in the elderly. However, particularly careful management of LDL levels in men seems to be warranted. Dr. John Krystal, Editor of Biological Psychiatry, agreed, noting that "these new data provide yet another important reason that doctors and patients should monitor and regulate cholesterol levels carefully, through a combination of diet and medication."

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Marie-Laure Ancelin, Isabelle Carrière, Jean-Philippe Boulenger, Alain Malafosse, Robert Stewart, Jean-Paul Cristol, Karen Ritchie, Isabelle Chaudieu, Anne-Marie Dupuy. Gender and Genotype Modulation of the Association Between Lipid Levels and Depressive Symptomatology in Community-Dwelling Elderly (The ESPRIT Study). Biological Psychiatry, 2010; 68 (2): 125 DOI: 10.1016/j.biopsych.2010.04.011

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Bone cells' branches sense stimulation, when to make new bone

Bone Cells' Branches Sense Stimulation, When to Make New Bone


ScienceDaily (July 20, 2010) — A long-standing question in bone biology has been answered: It is the spindly extensions of bone cells that sense mechanical stimulation and signal the release of bone-growth factors, according to research from The University of Texas Health Science Center at San Antonio.



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The study, reported in Proceedings of the National Academy of Sciences, offers an important clue for developing therapies to treat the bone-thinning disease osteoporosis and bone loss associated with aging, said Jean Jiang, Ph.D., senior corresponding author from the Department of Biochemistry, UT Health Science Center Graduate School of Biomedical Sciences.
Sensitive extensions
"Osteocytes are the most abundant cells in bone," Dr. Jiang said. "In the field of bone biology, there was a long-standing debate as to which part of the osteocyte senses mechanical loading. In this study, we demonstrate for the first time that it is the extensions, which are called dendrites."
Regular physical exercise is highly beneficial in maintaining bone health and in prevention of bone loss and osteoporosis. Mechanical stimulation of the bone through weight bearing is critical for promoting bone remodeling, said Sirisha Burra, Ph.D., lead author from the Department of Biochemistry.
"Maintenance of bone health depends on the osteocytes' ability to sense the stimulation," Dr. Burra said. "If osteocytes lose this ability, it could possibly lead to diseases such as osteoporosis. Hence, it is important to understand this mechanism."
Mechanical impact
The Health Science Center collaborated with Southwest Research Institute in San Antonio to estimate the mechanical impact of force applied to the dendrites. Magnitudes of mechanical stress were determined.
"Understanding how bone cells sense and respond to mechanical signals within the skeleton is an inherently multidisciplinary problem," said co-author Daniel P. Nicolella, Ph.D., institute engineer in the Mechanics and Materials Section at Southwest Research Institute. "We determined the mechanical stresses applied to the osteocytes in these experiments so that they can be compared to the mechanical signals predicted to occur within the skeleton during routine physical activities."
Toll of osteoporosis
Approximately 8 million women and 2 million men have osteoporosis in the U.S. Affected bone becomes brittle and can fracture with minor falls. In severe cases, a bone can even break from a sneeze. Another 34 million Americans are estimated to have low bone mass and are at higher risk for osteoporosis. (Source: National Osteoporosis Foundation)
Bone loss has been observed in astronauts who have spent a long time in space. Greater understanding of the process of bone remodeling could also aid in the discovery of solutions for the degenerative joint disease osteoarthritis.
Intriguing idea
Apart from its clinical implications, the study is intriguing because it "brings in a novel thought that different parts of a single cell can have different material and sensory properties," Dr. Jiang said. "Different parts of the cell can react differently to the same stimulus. This is a very important fact to consider while studying cellular signaling and regulatory mechanisms."
This research was supported by grants from the National Institutes of Health and The Welch Foundation. Published online before print July 19, 2010, doi: 10.1073/pnas.1009382107

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Texas Health Science Center at San Antonio, via EurekAlert!, a service of AAAS.




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Sirisha Burra, Daniel P. Nicolella, W. Loren Francis, Christopher J. Freitas, Nicholas J. Mueschke, Kristin Poole, and Jean X. Jiang. Dendritic processes of osteocytes are mechanotransducers that induce the opening of hemichannels. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1009382107

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A high-fat diet alters crucial aspects of brain dopamine signaling

A High-Fat Diet Alters Crucial Aspects of Brain Dopamine Signaling


ScienceDaily (July 19, 2010) — Research to be presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior, finds that prolonged exposure to a high fat diet is correlated with changes in the brain chemical dopamine within the striatum, a critical component of the brain's reward system.



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Greater obesity in offspring of nursing mothers consuming a high-fat diet

Greater Obesity in Offspring of Nursing Mothers Consuming a High-Fat Diet


ScienceDaily (July 19, 2010) — The future health of offspring is more negatively impacted when their mothers consume a high fat diet while nursing compared with high-fat diet consumption during pregnancy, according to animal research at Johns Hopkins University. These new research results were presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB).



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Obesity is associated with reduced sensitivity to fat

Obesity Is Associated With Reduced Sensitivity to Fat


ScienceDaily (July 19, 2010) — Research presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB) finds marked differences between obese and lean men in how they respond to the taste of fat. Fat also is less effective in obese men in stimulating certain gut hormones that are released into the bloodstream and normally suppress appetite.



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A high-fat diet alters crucial aspects of brain dopamine signaling

A High-Fat Diet Alters Crucial Aspects of Brain Dopamine Signaling


ScienceDaily (July 19, 2010) — Research to be presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior, finds that prolonged exposure to a high fat diet is correlated with changes in the brain chemical dopamine within the striatum, a critical component of the brain's reward system.



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The authors measured 'real-time' changes in dopamine levels after rats consumed a high fat diet for either 2 or 6 weeks. Compared to rats consuming a standard low fat diet, high-fat diet rats exhibited reduced dopamine release and also reduced reuptake by "dopamine transporters" within the striatum. Mitchell Roitman from the University of Illinois at Chicago says, "Previous research has demonstrated reduced dopamine transporter numbers in association with obesity and exposure to a high fat diet. Our research shows that these changes lead to major differences in the way dopamine functions in the brain."
The results from this study highlight the impact of diet on brain neurochemistry -- and in particular on brain systems that regulate motivation and willingness to work for food reward in rats as well as humans.
Research supported by the National Institute on Drug Abuse (NIDA).
The lead author is Jackson J. Cone, University of Illinois at Chicago, Chicago, IL, USA. Co-authors are J.D. Roitman and M.F. Roitman, University of Illinois at Chicago, Chicago, IL, USA

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Greater obesity in offspring of nursing mothers consuming a high-fat diet

Greater Obesity in Offspring of Nursing Mothers Consuming a High-Fat Diet


ScienceDaily (July 19, 2010) — The future health of offspring is more negatively impacted when their mothers consume a high fat diet while nursing compared with high-fat diet consumption during pregnancy, according to animal research at Johns Hopkins University. These new research results were presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB).



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The researchers used a method called "cross-fostering" to determine whether prenatal or postnatal exposure to maternal high fat diet has a greater influence on the development of obesity and diabetes in the offspring. Rats were fed either a low fat or high fat diet during pregnancy. After birth, pups born to mothers that consumed either diet were fostered over to different mother rats that ate the same or opposite diet during the nursing period. The researchers found that rat pups nursed by mothers consuming a high fat diet gained more body weight and were obese when weaned a few weeks later, even if the pup's biological mother ate a low fat diet during pregnancy. In addition to being obese, pups nursed by foster mothers on a high fat diet displayed impaired glucose tolerance, an early indicator of diabetes.
According to lead author, Bo Sun, "These results suggest that high fat diet intake by nursing mothers may be more critical to the later development of obesity and diabetes in their offspring than high fat feeding during pregnancy. Therefore, to help prevent obesity and metabolic problems in their offspring, it may be most important for mothers to avoid consuming too much fat in their diet while nursing."
The lead author was Bo Sun of Dept. of Psychiatry & Behavioral Sciences, Johns Hopkins Univ., Baltimore, MD, USA
Co-Authors were R. Purcell, T. Moran and K. Tamashiro of  the Dept. of Psychiatry & Behavioral Sciences, Johns Hopkins Univ., Baltimore, MD, USA,  and J.Q. Yan of the Dept. of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an, China.

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