2005

Endocrinology. 2005 May 26.
The Role of Oxidative Stress in relation to Caloric Restriction and Longevity.
Gredilla R, Barja G.
Department of Animal Physiology-II, Faculty of Biology, Complutense University, Madrid 28040, Spain.

Reduction of the caloric intake without malnutrition is one of the most consistent experimental interventions increasing mean and maximum life span in different species. For over seventy years caloric restriction has been studied, and during the last years the number of investigations on such nutritional intervention and aging has dramatically increased. Since caloric restriction decreases the aging rate, it constitutes an excellent approach to better understand the mechanisms underlying the aging process. Different investigations have reported reductions in steady-state oxidative damage to proteins, lipids and DNA in animals subjected to restricted caloric intake. Most interestingly, several investigations have reported that these decreases in oxidative damage are related to a lowering of mitochondrial free radical generation rate in different tissues of the restricted animals. Thus, similarly to what has been described for long-lived animals in comparative studies, a decrease in mitochondrial free radical generation has been suggested to be one of the main determinants of the extended life span observed in restricted animals. Here we review recent studies on caloric restriction and longevity, focusing on mitochondrial oxidative stress and the proposed mechanisms leading to an extended longevity in caloric restricted animals.

Toxicol Pathol. 2005;33(3):386-97.
An investigation of the effects of late-onset dietary restriction on prostate cancer development in the TRAMP mouse.
Suttie AW, Dinse GE, Nyska A, Moser GJ, Goldsworthy TL, Maronpot RR.
Integrated Laboratory Systems, Research Triangle Park, North Carolina 27709, USA.

In our previous work we showed that dietary restriction initiated at puberty reduced prostate cancer development in the TRAMP mouse model. The current study was conducted to ascertain whether a dietary restriction regime would similarly reduce lesion development if imposed once tumor development was well established. Male TRAMP mice were maintained on an ad libitum diet until 20 weeks of age when proliferative prostate lesions are clearly evident. Mice were then subjected to a 20% restriction in dietary calories compared to matched controls, which were continued on ad libitum feeding. Mice were sacrificed at 20, 24, 32, and 39 weeks of age and proliferative epithelial lesions of the prostate were assessed using an established grading scheme. In this study, although dietary restriction reduced mean sex pluck weight (prostate and seminal vesicles), and mean grade of epithelial proliferative lesions in the dorsal and lateral lobes of the prostate, the effect was not as pronounced as was the case with dietary restriction from puberty. There was no relationship between serum insulin like growth factor (IGF-1) and prostate lesion grade. Additionally, we also report the relationship between lobe specific lesion development and SV40 immunostaining and, the occurance of neuroendocrine tumors (NETs) in the ventral prostate and urethra of the TRAMP mouse. NETs stained with high specificity and sensitivity for the neuroendocrine markers, synaptophysin and neuron-specific enolase (NSE), less for serotonin, but not for chromogranin A. NETs did not stain for cyclo-oxygenase-2 (COX-2) nor androgen receptor (AR). SV40 positive tubulo-acinar tumors seen occasionally in the kidney, did not stain for synaptophysin nor NSE.

2004

J Clin Endocrinol Metab. 2004 Nov;89(11):5402-9.
Endocrine and metabolic effects of physiologic r-metHuLeptin administration during acute caloric deprivation in normal-weight women.
Schurgin S, Canavan B, Koutkia P, Depaoli AM, Grinspoon S.
Program in Nutritional Metabolism, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, LON 207, Boston, Massachusetts 02114, USA.

Leptin is a nutritionally regulated hormone that may modulate neuroendocrine function during caloric deficit. We hypothesized that administration of low-dose leptin would prevent changes in neuroendocrine function resulting from short-term caloric restriction. We administered physiologic doses of r-metHuLeptin [(0.05 mg/kg sc daily or identical placebo in divided doses (0800, 1400, 2000, and 0200 h)] to 17 healthy, normal-weight, reproductive-aged women during a 4-d fast. Leptin levels were lower in the placebo-treated group during fasting (3.3 +/- 0.2 vs. 9.6 +/- 1.0 ng/ml, P < 0.001, placebo vs. leptin-treated at end of study). Fat mass decreased more in the leptin than the placebo-treated group (-0.6 +/- 0.1 vs. -0.2 +/- 0.1 kg, P = 0.03). Both overnight LH area (38.9 +/- 21.5 vs. 1.2 +/- 11.1 microIU/ml.min, P = 0.05) and LH peak width increased (15.8 +/- 7.1 vs. -2.3 +/- 6.7 min, P = 0.06) and LH pulsatility decreased (-2.0 +/- 0.9 vs. 1.0 +/- 0.8 peaks/12 h, P = 0.03) more in the leptin vs. placebo group. LH pulse regularity was higher in the leptin-treated group (P = 0.02). Twenty-four-hour mean TSH decreased more in the placebo than the leptin-treated group, respectively (-1.06 +/- 0.27 vs. -0.32 +/- 0.18 microIU/ml, P = 0.03). No differences in 24-h mean GH, cortisol, IGF binding protein-1, and IGF-I were observed between the groups. Hunger was inversely related to leptin levels in the subjects randomized to leptin (r = -0.76, P = 0.03) but not placebo (r = -0.18, P = 0.70) at the end of the study. Diminished hunger was seen among subjects achieving the highest leptin levels. Our data provide new evidence of the important role of physiologic leptin regulation in the neuroendocrine response to acute caloric deprivation.

2000

Prev Med 2000 Feb;30(2):95-102.
Reduction of plasma catecholamines in humans during clinically controlled severe underfeeding.
Gohler L., Hahnemann T., Michael N., Oehme P., Steglich HD., Conradi E., Grune T.
Siems Clinics of Physical Medicine and Rehabilitation, University Hospital Charite, Humboldt University, Berlin, Germany.

BACKGROUND: Sympathetic hyperactivity is one factor for alterations encountered in the plurimetabolic syndrome, a cluster of metabolic abnormalities including obesity, hyperlipidemia, sometimes hyperglycaemia, and hypertonia. It was interesting to know if prolonged severe underfeeding (230 kcal/day) leads to decreases in catecholamines in those patients. METHODS: The plasma concentrations of catecholamines in patients (n = 16) suffering from plurimetabolic syndrome were studied before and during a 16-day period of medically controlled severe underfeeding (230 kcal/day) at rest and in response to exercise. RESULTS: During the period of underfeeding, mean norepinephrine concentrations decreased at rest from 1.45 to 0. 96 nmol/liter, and in response to exercise, from 6.1 to 3.2 nmol/liter. Epinephrine concentrations decreased from 0.15 to 0.1 nmol/liter and from 0.26 to 0.17 nmol/liter, respectively. A significant decrease in catecholamine concentrations was observed only after 16 days of underfeeding. CONCLUSIONS: Clinically controlled underfeeding of patients with plurimetabolic syndrome may result in beneficial clinical and biochemical effects. The findings indicate that relatively long periods of underfeeding induce decreases in plasma catecholamine concentrations. Nevertheless, most of the fall in mean values in norepinephrine and also of the fall in blood pressure values occurred by Day 2. From those tendencies and from the significant changes in both parameters at Day 16 of severe underfeeding one could conclude that altered sympathetic nervous system activity could contribute to the fall in blood pressure.

Eur J Endocrinol 2000 Feb;142(2):125-30.
Changes in renal tri-iodothyronine and thyroxine handling during fasting.
Rolleman EJ., Hennemann G., van Toor H., Schoenmakers CH., Krenning EP., de Jong M.
Department of Internal Medicine III, Academic University Hospital Dijkzigt and Erasmus Medical School, Rotterdam, The Netherlands.

OBJECTIVE: Liver handling of thyroid hormones (TH) has been known to alter significantly during fasting. This study investigates whether renal handling of TH is also changed during fasting. METHODS: We measured urinary excretion rates and clearances of free tri-iodothyronine (T(3)) and free thyroxine (T(4)) in healthy subjects prior to and on the third day of fasting. RESULTS: During fasting, both mean T(3) and T(4) urinary excretion decreased significantly to a mean value of 42% of control. Also, total and free (F) serum T(3) concentrations declined significantly, but serum T(4) did not change. Both FT(3) and FT(4) clearance decreased significantly during fasting (62% and 42% of control). The fasting-induced decrease in uric acid clearance correlated well with the decrease in FT(3) clearance (r=0.94; P<0.001). Serum concentrations of non-esterified fatty acids (NEFA) were significantly elevated during fasting. CONCLUSIONS: The findings cannot be fully explained by the fasting-induced decrease in serum T(3), and are in accordance with inhibition of uptake of T(3) and T(4) at the basolateral membrane of the tubular cell. This inhibition may be caused by a decreased energy state of the tubular cell and by other factors such as ketoacidosis and/or increased NEFA concentrations during fasting.

1997

Am J Clin Nutr 1997 Jul;66(1):147-52.
Alterations in lymphocyte subsets and pituitary-adrenal gland-related hormones during fasting.
Komaki G., Kanazawa F., Sogawa H., Mine K., Tamai H., Okamura S., Kubo C.
Department of Psychosomatic Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.

We investigated changes in the immunoendocrine system during fasting. Ten hospitalized patients aged 14-46 y with psychosomatic disorders fasted for 7 or 10 d. Blood samples were collected before and on days 3 and 7 of the 7-d fasts. When fasting continued to 10 d, an additional sample was taken on day 10. We measured blood cellularity (white blood cells and total lymphocytes), the total number and percentage of lymphocyte subsets (CD2, CD3, CD4, CD8, and CD19), natural killer (NK) cell activity, cytokines (interleukin 1 beta, interleukin 2, interleukin 6, granulocyte-macrophage colony stimulating factor, tumor necrosis factor alpha, and interferon gamma), and soluble interleukin 2 receptors. Corticotropin, cortisol, and dehydroepiandrosterone sulfate (DHEAS) concentrations were also determined. Although the total number of lymphocytes decreased during fasting, NK cell activity increased significantly. Plasma cortisol and DHEAS concentrations also increased significantly whereas changes in corticotropin concentrations were not significant. The total number and percentage of CD4 cells decreased significantly during fasting but no other lymphocyte subsets changed significantly. The percentage of CD4 cells was negatively correlated with cortisol concentrations during fasting. No detectable changes occurred in cytokines or soluble interleukin 2 receptors during the study. All measured immunoendocrine values that changed during fasting returned to prefasting values during the refeeding period. These findings indicate that fasting affects immune variables such as T cell subsets and NK cell activity at least in part through changes in adrenal gland-related hormones.

1996

J Clin Endocrinol Metab 1996 Sep;81(9):3419-23.
Effect of fasting on serum leptin in normal human subjects.
Boden G; Chen X; Mozzoli M; Ryan I.
Division of Endocrinology/Diabetes/Metabolism, Temple University School of Medicine, Philadelphia, PA 19140, USA.

ABSTRACT: We have studied the effect of fasting on serum leptin levels in normal volunteers. Five normal-weight (BMI < 28, 2 males/3 females) and five obese subjects (BMI > 28, 2 males/3 females) were fasted (0 Kcal) for 52 h. Mean plasma glucose decreased from 88 +/- 3 to 63 +/- 5 mg/dl, serum insulin from 16 +/- 1 to 10 +/- 1 microU/ml, plasma beta-hydroxybutyrate increased from 0.2 +/- 0.1 to 1.8 +/- 0.4 mumol/ml. Serum leptin levels were higher in the obese than in the normal-weight volunteers (31 +/- 12 vs 11 +/- 3 ng/ml, p < 0.01). In the obese, serum leptin decreased from 31 +/- 10 to 12 +/- 5 ng/ml aft552 h (-72%, p < 0.001); in the normal-weight it decreased from 11 +/- 3 to 4 +/- 0.5 ng/ml (-64%, p < 0.001). Serum leptin correlated positively with serum insulin (r = 0.51, p < 0.001) and with plasma glucose (r = 0.61, p < 0.001). To determine effects of fasting induced decreases in plasma glucose and insulin on serum leptin, four normal subjects (3 males/1 female) were fasted for 72 h while their plasma glucose was clamped at basal levels with a variable rate glucose infusion. In these volunteers, serum leptin and insulin concentrations remained unchanged. In summary, the rapid decrease in serum leptin levels during fasting indicated that leptin release was regulated by factors other than changes in body fat mass. The lack of leptin changes during fasting, when basal insulin and glucose levels were maintained at basal levels, suggested that insulin and/or glucose may play a role in the regulation of leptin release.

1995

Neurobiol Aging 1995 Sep-Oct;16(5):837-43; discussion 855-6.
Neuroendocrine involvement in aging: evidence from studies of reproductive aging and caloric restriction.
Nelson JF; Karelus K; Bergman MD; Felicio LS.
Department of Physiology, University of Texas Health Science Center, San Antonio 78284-7756, USA.

ABSTRACT: Neuroendocrine changes contribute to female reproductive aging, but changes in other tissues also play a role. In C57BL/6J mice, neuroendocrine changes contribute to estrous cycle lengthening and reduced plasma estradiol levels, but the midlife loss of cyclicity is mainly due to ovarian failure. Hypothalamic estrogen receptor dynamics and estrogenic modulation of gene _expression are altered in middle-aged cycling mice. Although insufficient to arrest cyclicity, these neuroendocrine changes may contribute to other reproductive aging phenomena, such as altered gonadotropin secretion and lengthened estrous cycles. In women, the loss of ovarian oocytes, the cause of menopause, accelerates in the decade before menopause. Accelerated oocyte loss may in turn be caused by a selective elevation of plasma follicle stimulating hormone, and neuroendocrine involvement may thus be implicated in menopausal oocyte loss. Chronic calorie restriction retards both neural and ovarian reproductive aging processes, as well as age-related change in many other physiological systems. The diverse effects of food restriction raises the possibility of an underlying coordinated regulatory response of the organism to reduced caloric intake, possibly effected through alterations of neural and/or endocrine signalling. We are therefore attempting to identify neuroendocrine changes that may coordinate the life prolonging response of animals to food restriction. Our initial focus is on the glucocorticoid system. Food restricted rats exhibit daily periods of hyperadrenocorticism, manifest as elevated free corticosterone during the diurnal peak. We hypothesize that this hyperadrenocortical state potentiates cellular and organismic homeostasis throughout life in a manner similar to that achieved during acute stress, thereby retarding aging processes and extending life span.

1991

J Pharmacol Exp Ther 1991 May;257(2):647-50.
Changes of endogenous morphine and codeine contents in the fasting rat.
Lee CS; Spector S.
Department of Neurosciences, Roche Institute of Molecular Biology, Nutley, New Jersey.

The alteration of endogenous opiate alkaloids during fasting state was investigated in rats. The concentrations of morphine and codeine in the cortex, midbrain, pons plus medulla, cerebellum, adrenal gland and pancreas were measured using radioimmunoassay for the opiates following high pressure liquid chromatography. The morphine and codeine contents of fasting rats showed maximum elevated levels in cortex, pons plus medulla and pancreas after 2 days of fasting, but after 1 day in midbrain. The opiate content of the cerebellum showed a tendency for a continuous increase during the 4 days. Adrenal glands of fasting rats had elevated levels at days 3 and 4, although there were great fluctuations within the groups.