The role of malnutrition in older persons with mobility limitations

Movement disability has a high prevalence in elderly population, either healthy or with chronic disease. Impaired nutritional status is a very common condition in geriatric patients too, especially if we consider elderly subjects admitted to hospital. There are growing evidences that nutrition and disability are strictly interconnected. On the one side, nutritional status is one of the multiple elements that influence the onset and the course of a functional disability; on the other side, disability itself may contribute to malnutrition onset and worsening. Nutrition may not be the sole factor involved in movement impairment in the elderly, but consciousness of its importance in frail elderly population is growing among clinicians and scientific community. In this paper we review the existing knowledge of these complex relationships, discussing the main observational and interventional studies that explored the role of nutrition in movement disability onset and recovery. We also point out how specific kinds of diet, such as Mediterranean diet or high-protein diet, are involved in disability prevention. Finally, we take a look at the existing evidence of the role of single nutrient dietary intake, such as carotenoids, selenium or vitamin D, in mobility impairment in the elderly population.

Relationship between use of proton pump inhibitors and IGF system in older subjects

OBJECTIVES

to investigate the effects of proton pump inhibitors (PPIs) on the insulin-like-growth factor 1(IGF-1) system in the elderly.

DESIGN

cross-sectional.

SETTING

InCHIANTI study.

PARTICIPANTS

938 older subjects (536 women, 402 men, mean age 75.7±7.4 years).

MEASUREMENTS

complete data on age, sex, BMI, liver function, medications, dietary intake, IGF-1, IGF-binding protein-1 and -3 (IGFBP-1, IGFBP-3).

RESULTS

Participants were categorized by PPI use, identifying 903 PPI non users and 35 users. After adjusting for age, male PPI users (107.0 ± 69.6 vs. 127.1 ± 55.8, p<0.001) and female PPI users (87.6 ± 29.1 vs. 107.6 ± 52.3, p=0.03) had lower IGF-1 levels than non-users. IGFBP-1 levels were similar in the two groups in both sexes. In whole population, after adjustment for age and sex, PPI users had lower IGF-1 levels 81.9 [61.1-113.8] than non-users 110 [77.8-148.6], p=0.02. After further adjustment for BMI, albumin, liver function, C-reactive protein, Interleukin-6, number of medications, ACE-inhibitors use, caloric intake, protein intake, physical activity, glycemia, and IGFBP-1, the use of PPIs remained significantly and negatively associated with IGF-1 levels (β±SE = -19.60±9.83, p=0.045).

CONCLUSION

Use of PPIs was independently and negatively associated with IGF-1 levels.

Is the haematopoietic effect of testosterone mediated by erythropoietin? The results of a clinical trial in older men

The stimulatory effects of testosterone on erythropoiesis are very well known, but the mechanisms underlying the erythropoietic action of testosterone are still poorly understood, although erythropoietin has long been considered a potential mediator. A total of 108 healthy men >65 years old with serum testosterone concentration <475 ng/dL were recruited by direct mailings to alumni of the University of Pennsylvania and Temple University, and randomized to receive a 60-cm(2) testosterone or placebo patch for 36 months. Ninety-six subjects completed the trial. We used information and stored serum specimens from this trial to test the hypothesis that increasing testosterone increases haemoglobin by stimulating erythropoietin production. We used information of 67 men, 43 in the testosterone group and 24 in the placebo group who had banked specimens available for assays of testosterone, haemoglobin and erythropoietin at baseline and after 36 months. The original randomized clinical study was primarily designed to verify the effects of testosterone on bone mineral density. The primary outcome of this report was to investigate whether or not transdermal testosterone increases haemoglobin by increasing erythropoietin levels. The mean age ± SD of the 67 subjects at baseline was 71.8 ± 4.9 years. Testosterone replacement therapy for 36 months, as compared with placebo, induced a significant increase in haemoglobin (0.86 ± 0.31 g/dL, p = 0.01), but no change in erythropoietin levels (-0.24 ± 2.16 mIU/mL, p = 0.91). Included time-varying measure of erythropoietin did not significantly account for the effect of testosterone on haemoglobin (Treatment-by-time: β = 0.93, SE = 0.33, p = 0.01). No serious adverse effect was observed. Transdermal testosterone treatment of older men for 36 months significantly increased haemoglobin, but not erythropoietin levels. The haematopoietic effect of testosterone does not appear to be mediated by stimulation of erythropoietin production.

The relationship between sex hormones, sex hormone binding globulin and peripheral artery disease in older persons

OBJECTIVE

The prevalence of peripheral artery disease (PAD) increases with aging and is higher in persons with metabolic syndrome and diabetes. PAD is associated with adverse outcomes, including frailty and disability. The protective effect of testosterone and sex hormone binding globulin (SHBG) for diabetes in men suggests that the biological activity of sex hormones may affect PAD, especially in older populations.

METHODS

Nine hundred and twenty-one elderly subjects with data on SHBG, testosterone (T), estradiol (E2) were selected from InCHIANTI study. PAD was defined as an Ankle-Brachial Index (ABI) < 0.90. Logistic regression models adjusted for age (Model 1), age, BMI, insulin, interleukin-6, physical activity, smoking, chronic diseases including metabolic syndrome (Model 2), and a final model including also sex hormones (Model 3) were performed to test the relationship between SHBG, sex hormones and PAD.

RESULTS

The mean age (±SD) of the 419 men and 502 women was 75.0 ± 6.8 years. Sixty two participants (41 men, 21 women) had ABI < 0.90. Men with PAD had SHBG levels lower than men without PAD (p = 0.03). SHBG was negatively and independently associated with PAD in men (p = 0.028) but not in women. The relationship was however attenuated after adjusting for sex hormones (p = 0.07). The E2 was not significantly associated with PAD in both men and women. In women, but not in men, T was positively associated with PAD, even after adjusting for multiple confounders, including E2 (p = 0.01).

CONCLUSIONS

Low SHBG and high T levels are significantly and independently associated with the presence of PAD in older men and women, respectively.

The hormonal pathway to cognitive impairment in older men

In older men there is a multiple hormonal dysregulation with a relative prevalence of catabolic hormones such as thyroid hormones and cortisol and a decline in anabolic hormones such as dehydroepiandrosterone sulphate, testosterone and insulin like growth factor 1 levels. Many studies suggest that this catabolic milieu is an important predictor of frailty and mortality in older persons. There is a close relationship between frailty and cognitive impairment with studies suggesting that development of frailty is consequence of cognitive impairment and others pointing out that physical frailty is a determinant of cognitive decline. Decline in cognitive function, typically memory, is a major symptom of dementia. The "preclinical phase" of cognitive impairment occurs many years before the onset of dementia. The identification of relevant modifiable factors, including the hormonal dysregulation, may lead to therapeutic strategies for preventing the cognitive dysfunction. There are several mechanisms by which anabolic hormones play a role in neuroprotection and neuromodulation. These hormones facilitate recovery after brain injury and attenuate the neuronal loss. In contrast, elevated thyroid hormones may increase oxidative stress and apoptosis, leading to neuronal damage or death. In this mini review we will address the relationship between low levels of anabolic hormones, changes in thyroid hormones and cognitive function in older men. Then, giving the contradictory data of the literature and the multi-factorial origin of dementia, we will introduce the hypothesis of multiple hormonal derangement as a better determinant of cognitive decline in older men.

Relationship between testosterone deficiency and cardiovascular risk and mortality in adult men

Classic male hypogonadism is associated with known adverse effects including decreased libido, erectile dysfunction, osteoporosis, and changes in body composition. Recently, we have come to appreciate that reduction in serum testosterone (T) levels resulting from aging or chronic disease or androgen deprivation therapy (ADT) have consequences similar to those seen in classic male hypogonadism which include increased fat mass, decreased lean body mass, decreased muscle strength, and sexual dysfunction. These data suggest that low T levels may represent a newly recognized cardiometabolic risk factor. Therefore, we carried out a careful review of the literature, focusing on major turning points of research and studies which gave more important and controversial contribution to the cardiovascular role of T. Observational studies and clinical trials investigating the relationship between T levels and cardiovascular disease and mortality were identified byMedline search. The results were synthesized, tabulated, and interpreted. The aim of this review is to discuss the association between low T levels and adverse metabolic profile such as insulin resistance, metabolic syndrome, and diabetes. We will also investigate the potential mechanisms by which male hypogonadism, especially age related or induced by ADT, may increase cardio-metabolic risk. Finally we will detail the emerging relationship between low T and mortality in men addressing also the reverse hypothesis that low T has a protective role by turning off T-dependent functions.

Magnesium and anabolic hormones in older men

Optimal nutritional and hormonal statuses are determinants of successful ageing. The age associated decline in anabolic hormones such as testosterone and insulin-like growth factor 1 (IGF-1) is a strong predictor of metabolic syndrome, diabetes and mortality in older men. Studies have shown that magnesium intake affects the secretion of total IGF-1 and increase testosterone bioactivity. This observation suggests that magnesium can be a modulator of the anabolic/catabolic equilibrium disrupted in the elderly people. However, the relationship between magnesium and anabolic hormones in men has not been investigated. We evaluated 399 ≥65-year-old men of CHIANTI in a study population representative of two municipalities of Tuscany (Italy) with complete data on testosterone, total IGF-1, sex hormone binding globulin (SHBG), dehydroepiandrosterone sulphate (DHEAS) and serum magnesium levels. Linear regression models were used to test the relationship between magnesium and testosterone and IGF-1. Mean age of the population was 74.18 ± 6.43 (years ± SD, age range 65.2-92.4). After adjusting for age, magnesium was positively associated with total testosterone (β ± SE, 34.9 ± 10.3; p = 0.001) and with total IGF-1 (β ± SE, 15.9 ± 4.8; p = 0.001). After further adjustment for body mass index (BMI), log (IL-6), log (DHEAS), log (SHBG), log (insulin), total IGF-1, grip strength, Parkinson's disease and chronic heart failure, the relationship between magnesium and total testosterone remained strong and highly significant (β ± SE, 48.72 ± 12.61; p = 0.001). In the multivariate analysis adjusted for age, BMI, log (IL-6), liver function, energy intake, log (insulin), log (DHEAS), selenium, magnesium levels were also still significantly associated with IGF-1 (β ± SE, 16.43 ± 4.90; p = 0.001) and remained significant after adjusting for total testosterone (β ± SE, 14.4 ± 4.9; p = 0.01). In a cohort of older men, magnesium levels are strongly and independently associated with the anabolic hormones testosterone and IGF-1.

The impact of omega-3 fatty acids on osteoporosis

The essential polyunsaturated fatty acids (PUFAs) comprise 2 main classes: n-6 and n-3 fatty acids. The most common source of n-6 fatty acids is linoleic acid (LA) which is found in high concentrations in various vegetable oils. Arachidonic acid (AA), the 20-carbon n-6 fatty acid, is obtained largely by synthesis from LA in the body. The n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) are found in fish and fish oils. Long-Chain polyunsaturated fatty acids (LCPUFAs) and lipid mediators derived from LCPUFAs have critical roles in the regulation of a variety of biological processes including bone metabolism. There are different mechanisms by which dietary fatty acids affect bone: effect on calcium balance, effect on osteoblastogenesis and osteoblast activity, change of membrane function, decrease in inflammatory cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha), modulation of peroxisome proliferators-activated receptor gamma (PPARgamma). Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. In spite of increasing evidence of the positive effects of dietary fats on bone metabolism from animal and in vitro studies, the few studies conducted in humans do not allow us to draw a definitive conclusion on their usefulness in clinical practice.

Omega-3 and renal function in older adults

Chronic kidney disease (CKD) is a major public health problem and can result in end-stage renal disease with need for dialysis or transplantation. In Europe up to 12% of the adult population had some renal impairment, while in the United States the end stage of CKD has increased dramatically from 209.000 in 1991 to 472.000 in 2004. Diabetes and hypertension are major causes of kidney pathology. Infection, particularly ascending infection, is more common with increasing age, as both immune function declines and associated pathology predisposing to infection, such as obstructive uropathy, becomes more common. Most pathological changes in the kidney appear to be initiated by oxidative stress, followed by an inflammatory reaction. Oxidative stress results from an imbalance between free radicals and their detoxification by endogenous and exogenous scavengers, including polyunsaturated fatty acids (PUFA). Recent studies showed that PUFA supplementation slowed the rate of loss of renal function in patients with IgA nephropathy. Then, studies of omega-3 supplementation in dialysis patients describe salutary effects on triglyceride levels and dialysis access patency. We examined the relationship between total plasma PUFA levels and change in creatinine clearance over a three-year follow-up in the older persons enrolled in the InCHIANTI study, a population-based epidemiology study conducted in Tuscany, Italy. This study showed that older adults with low total plasma PUFA levels have a greater decline in creatinine clearance over three years of follow-up. These findings suggest that a higher dietary intake of PUFA may be protective against progression to chronic kidney disease.

Acute changes in circulating hormones in older patients with impaired ventricular function undergoing on-pump coronary artery bypass grafting

OBJECTIVES

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) causes an acute stress response characterized by changes in the levels of several hormones, which might play a role in the high complication rate experienced by older patients after CABG. Thus, the aim of the study was to investigate changes in the circulating levels of anabolic and catabolic hormones in old people undergoing CABG with CPB.

DESIGN

Intervention case study.

METHODS

19 patients (12 males, 7 females) aged 70.1 +/- 6.1 yr (age range 62-80) with coronary artery disease and an ejection fraction <40% who underwent cardiac surgery. Cortisol (Cort), DHEA, DHEAS, LH, estradiol (E2), total testosterone (Te), SHBG, IGF-I were measured the day before, on the day of the procedure and 1, 2, 3, 4, and 30 days after CABG.

RESULTS

After surgery, serum IGF-I levels decreased (p<0.001), while levels of Cort, DHEAS and E2 significantly increased in both men and women. Alterations in Te levels differed between the two sexes with a significant decline in men and a significant increment in women.

CONCLUSION

CABG with CPB resulted in a dramatic drop in Te levels in old men and a significant decline in IGF-I in both sexes. Serum Cort levels also significantly increased in both sexes. These hormonal changes may, at least partially, explain why the elderly need prolonged rehabilitation after CABG.

Thyroid disease in the elderly: sex-related differences in clinical expression

Thyroid diseases are more prevalent in females. This notion is mostly derived from studies conducted in adult subjects, but the knowledge of the relationship between sex and thyroid disease is becoming important for the epidemiological study of aging population. Aging has been proposed to represent a trigger for the development of autoimmune phenomena resulting in the production of both organ- and non-organ-specific antibodies. Studies on the relationship between sex and thyroid autoimmunity in elderly subjects have shown that the age-related prevalence of antithyroid autoantibodies is greater in women >60 yr of age. An increased prevalence of hypothyroidism has been demonstrated in the elderly population. Several factors may affect prevalence, but virtually all studies report higher prevalence rates for either overt or subclinical hypothyroidism in women with advancing age. This gender-related difference, however, has not been demonstrated for hospitalized patients. Difficulties are encountered in the attempt to estimate a sex-related difference in the prevalence of hyperthyroidism in elderly subjects. In most cases, Graves' disease and toxic multinodular goiter represent the cause of the disease with relative proportions depending on iodine intake. However, data on the prevalence of this disorder and on its sex-related frequency are significantly affected by underlying nodularity and functional autonomy. This phenomenon may be even more pronounced when excess iodine intake occurs and when patients are treated with iodine-containing drugs and thyroid hormone therapy. Subclinical hyperthyroidism is more common in women than in men, especially in subjects >70 yr. Both overt and subclinical hyperthyroidism arise from underlying thyroid nodular disease. The low-T3 syndrome is common in the elderly. Due to the fact that the low-T3 syndrome is often derived from underlying diseases, it is difficult do define a sex-related difference in its prevalence. However, in unselected elderly home-dwellers, an independent association of low-T3 syndrome with male gender has been shown. Aging represents an important factor to define the aggressiveness of thyroid carcinomas. Both follicular and anaplastic histotypes of thyroid cancer are more frequently found in elderly subjects. In aging subjects, male sex seems to be highly correlated with the risk of thyroid cancer. In conclusion, epidemiological data from the aging population confirms that men are less affected by thyroid disease than women. However, male sex may represent a risk factor for thyroid cancer in elderly population and this observation should be carefully considered in the evaluation of thyroid nodules in the elderly.

The relationship between testosterone and molecular markers of inflammation in older men

Aging is accompanied by a pro-inflammatory state expressed by the increasing levels of inflammatory cytokines, including interleukin-6 (IL- 6), tumor necrosis factor alpha (TNF-alpha) and interleukin- 1beta (IL-1beta). At the same time, aging is associated with a decrease in serum testosterone (T) levels. There is evidence from many experimental studies that IL-6, TNF-alpha and IL-1beta inhibit T secretion by their influence on the central (hypothalamic-pituitary) and peripheral (testicular) components of the gonadal axis. On the other hand, observational and interventional studies suggest that T supplementation reduces inflammatory markers in both young and old hypogonadal men. Preliminary data from 473 older male participants of the InCHIANTI population showed a significant inverse relationship between T and soluble IL-6 receptor (sIL-6r) levels (a soluble portion of the IL-6 receptor that may enhance the biological activity of IL-6) but not with other markers of inflammation. This study, together with previous observations, suggests that a close relationship exists between the development of a pro-inflammatory state and the decline in T levels, two trends that are often observed in aging men. In the context of this paradigm, we discuss androgen deprivation therapy, a treatment used in men with metastatic prostate cancer as an ideal model to improve our understanding of the relationship between T and inflammatory markers. We advocate the notion that changes in inflammatory markers and T in aging men are causally linked. However, longitudinal and interventional studies are needed to confirm that T can be used therapeutically, based on its anti-inflammatory properties.

The hormonal pathway to frailty in older men

Frailty, which is a state of high vulnerability that imparts a high risk of developing adverse health outcomes, affects many elderly subjects, especially men and women aged 80 yr and older (1). Although many different definitions of frailty have been proposed (2), a large portion of the recent literature has focused on the definition developed by L. Fried et al. (1) using the data from the Cardiovascular Health Study. Although this definition has not been officially recognized as the "gold standard" for the diagnosis of frailty, nonetheless most of the studies on frailty in the last 5 yr have used this definition. Several mechanisms have been hypothesized to have an important role in the development of frailty, including inflammation, coagulation and oxidative stress (3). Many authors implicate age-related hormonal changes to be directly or indirectly involved in the development of the frailty syndrome (4). Alterations in hypothalamic- pituitary-testicular, hypothalamic-pituitary-adrenal (HPA) and GH-IGF-I axes that accompany aging have been associated with single components of frailty, such as reduced muscle strength, bone strength or poor mobility (5, 6). However, most of these studies have focused on single hormonal changes rather than evaluating the parallel effect of aging on multiple hormonal axes. In addition, no interventional studies have specifically targeted frail older subjects (7). Since frailty by definition is a multi-system disorder, it is unlikely that changes in one axis (leading to a change in a single hormone) will explain the complexity of the dysregulation leading to frailty. Therefore, global measures of endocrine dysregulation that can discriminate between specific endocrine diseases and endocrine senescence should be developed. Observational and interventional studies will be needed to better define the role of "hormonal dysregulation", alone and in combination with other pathways, in the development of frailty in older men.

Clinical implications of the reduced activity of the GH-IGF-I axis in older men

During the last decade, a significant body of evidence has accumulated, indicating that IGF-I might play a role in several pathological conditions commonly seen during aging, such as atherosclerosis and cardiovascular disease (CVD), cognitive decline, dementia, sarcopenia and frailty. A vascular protective role for IGF-I has been suggested because of its ability to stimulate nitric oxide production from endothelial and vascular smooth muscle cells. In cross sectional studies, low IGF-I levels have been associated with unfavorable CVD risk factors profile, such as atherosclerosis, abnormal lipoprotein levels and hypertension, while in prospective studies, lower IGF-I levels predict future development of ischemic heart disease. The fall in IGF-I levels with aging correlates with cognitive decline and it has been suggested that IGF-I plays a role in the development of dementia. IGF-I is highly expressed within the brain and is essential for normal brain development. IGF-I has anti-apoptotic and neuroprotective effects and promotes projection neuron growth, dendritic arborization and synaptogenesis. Collectively, these data are consistent with a causal link between the age-related decline in GH and IGF-I levels and cognitive deficits in older persons. Finally, there is evidence of a relationship between declining GH and IGF-I levels and age-related changes in body composition and physical function. However, few studies have documented a precise role of IGF-I in the development of sarcopenia, frailty and poor mobility. We have recently documented that serum IGF-I is significantly associated with measures of muscle strength and physical performance in men and to a lesser extent in women. In conclusion, IGF-I is a pleiotropic hormone that in older persons may positively affect the cardiovascular system, the central nervous system and physical function.

Ultrasound-guided fine-needle capillary biopsy of thyroid nodules, coupled with on-site cytologic review, improves results

Fine-needle aspiration biopsy represents the most reliable test for cytologic evaluation of thyroid nodules. However, inadequate samples may occur leading to a repetition of the procedure with the consequence of patients' discomfort and poor compliance. In this paper, we present results from biopsy of thyroid nodules obtained by combining: (1) ultrasound (US) guidance, (2) no-aspiration technique, and (3) on-site review of specimens. A total of 465 nodules were biopsied in 307 patients. Solitary nodules and multinodular goiter were present in 36.8% and 63.1% of patients, respectively. After collection, each sample was smeared in duplicates, one of which was stained with hematoxylin and checked on-site by a cytopathologist. In cases of inadequate smears, biopsies were immediately repeated. All slides were then processed for final cytologic results, which were reported as benign in 427 nodules (91.8%), malignant in 12 nodules (2.5%), with follicular proliferation or suspicious for malignancy in 23 nodules (4.9%). Inadequate final cytology was reported in 3 nodules (0.6%). No statistically significant relationship was found between nodule size and adequacy of specimens. We conclude that the combination of US guidance, capillary collection with no-aspiration technique, and on-site review of slides, characterizes an advantageous method for thyroid nodule fine-needle biopsy.

Pituitary function in chronic heart failure in the elderly

Heart failure is a complex syndrome characterized by the activation of hemodynamic, immunologic and neurohormonal systems, which have beneficial effects in the short run, but will ultimately lead to secondary end-organ damage with worsening of LV remodeling and subsequent cardiac decompensation. A very important role seems to be played by modifications of the pituitary hormone systems. Due to the neurohormonal activation there is an increase in the activity in the renin angiotensin system, in the adrenergic nervous system, and in the cytokine system. In heart failure there is a decrease in many anabolic hormones, such as a decrease of GH and IGF-I, of DHEA/DHEAS with normal or increased F, and a decrease of LH and sex steroids, resulting in an important catabolic drive, capable of contributing to the development of cardiac failure and to sarcopenia and/or cachexia, frequently observed in the advanced stages of the disease. However, these hormone alterations have been described in relatively young patients with chronic heart failure, since the mean age of all the subjects studied was of about 60 yr and none of the studies have specifically addressed this issue in the very old patients, who represent the largest portion of population affected by this pathological condition. The role of hormone replacement therapy needs to be verified in a population of elderly patients with heart failure.

Evaluation of the circadian profiles of serum dehydroepiandrosterone (DHEA), cortisol, and cortisol/DHEA molar ratio after a single oral administration of DHEA in elderly subjects

Aging is associated with a selective decline in circulating levels of dehydroepiandrosterone (DHEA) and its sulfate, with no major changes in cortisol secretion. In young subjects, serum levels of both DHEA and cortisol are regulated according to a circadian rhythm, and an age-related attenuation of DHEA, but not cortisol, circadian rhythmicity has been reported. Several trials have evaluated the effects of DHEA supplementation in elderly subjects, although the results are still controversial. However, no data are available on the 24-hour profile of DHEA circulating levels in elderly subjects with DHEA administration. In the present study, we evaluated the circadian rhythms of DHEA, cortisol, and the cortisol/DHEA molar ratio in old subjects treated with either placebo (old-PL) or a single 50-mg dose of DHEA (old-D), both administered orally at 0700 hours. For each variable, the circadian profiles were compared with those obtained in young control subjects. The group of young subjects displayed a circadian rhythm for both DHEA and cortisol serum concentrations but no rhythm for the cortisol/DHEA molar ratio. In the old-PL group, the circadian rhythm of DHEA was completely abolished, whereas significant rhythms for both cortisol and the cortisol/DHEA molar ratio were observed. Particularly, at each time point, the cortisol/DHEA molar ratio was significantly higher in these subjects versus the young group. In the old-D group, the circadian rhythm of DHEA was completely restored and was comparable to that observed in the young group. Analogous to the observations in young subjects, the profile of the cortisol/DHEA molar ratio in old-D subjects did not display any circadian rhythmicity, the values being almost completely comparable to those observed in young controls. Our data demonstrate that the circadian rhythm of DHEA is totally abolished in elderly subjects. A single 50-mg dose of DHEA administered orally at 0700 hours restores the circadian rhythmicity of serum DHEA and almost completely normalizes the 24-hour profile of the cortisol/DHEA molar ratio in old subjects without affecting the cortisol circadian rhythm.

Aging-related decline of gonadal function in healthy men: correlation with body composition and lipoproteins

OBJECTIVE

To assess if androgen decline in physiological aging contributes to the concomitant changes in body composition and lipoprotein levels.

DESIGN

Cross-sectional, observational study.

SETTING

A university-based outpatient center.

SUBJECTS

The study comprised 206 healthy volunteers (aged 18-95 years).

MEASUREMENTS

Blood samples were drawn after an overnight fast for the assay of hormones (free testosterone (FT), estradiol (E2), and sex hormone-binding globulin (SHBG)) and lipids (total cholesterol, triglycerides, high-density lipoprotein cholesterol, and lipoprotein Lp(a)). At the same time, body composition was assessed by both anthropometry (fat mass percentage (FM%) estimated from four measures of skinfold thickness using the Durnin and Womersley equation and the Siri equation) and by bioimpedance analysis (FM% estimated using the Segal or Deurenberg equations, respectively, for subjects younger or older than 62 years).

RESULTS

A significant age-related decline was found for FT and E2 concentrations, whereas SHBG levels were related positively with age. No significant association was apparent between hormonal changes and the concomitant modifications of body composition and lipoproteins. Only SHBG showed a significant inverse association between FM% and the waist-to-hip ratio, independent of age. The comparison between older hypogonadal (with FT levels below the lower limit of the normality range assessed in younger subjects) and eugonadal men did not show any significant differences in body composition or lipid profile.

CONCLUSIONS

This study suggests that, in men, androgen decline caused by normal aging does not significantly affect some targets of testosterone action, such as body composition and lipid metabolism. Therefore, androgen supplementation in hypogonadal older men cannot be expected to influence nutritional status and body composition to the same extent that it does other main targets of testosterone action, such as sexual activity and muscle strength. However, we cannot exclude that selected subsets of older patients with low testosterone levels, especially if affected by catabolic disease, could benefit from the effects of androgen administration on nutritional status.

Age-related variations in the neuroendocrine control, more than impaired receptor sensitivity, cause the reduction in the GH-releasing activity of GHRPs in human aging

The mechanisms underlying the reduction in the GH-releasing activity of GHRPs in aging are still unclear. Aim of our study was to verify in man whether age-related impairment of the neurohormonal control of GH secretion and/or receptor alterations are involved in the reduced GH response to GHRPs in aging. To this goal, in 16 normal elderly subjects (E, 66-81 yr) and 12 young controls (Y, 24-28 yr) we studied the effects of 1.0, 2.0 and 3.0 micrograms/kg i.v. Hexarelin (HEX), a synthetic hexapeptide, or GHRH, as well as the interaction among HEX (2.0 micrograms/kg), GHRH (2.0 micrograms/kg) and arginine (ARG, 0.5 gr/kg) on GH secretion. In Y the GH response to increasing doses of HEX (1.0 vs. 2.0 vs. 3.0 micrograms/kg; AUC0;v-120 +/- SEM: 1728.4 +/- 406.4 vs. 2265.9 +/- 298.4 vs. 2934.3 +/- 482.2 micrograms/L/h, p < 0.05 for 1.0 vs. 2.0 micrograms/kg) and GHRH (649.6 +/- 111.4 vs. 792.2 +/- 117.6 vs. 1402.6 +/- 363.0 micrograms/L/h) showed a progressive increase. Two micrograms/kg HEX and 1 microgram/kg GHRH were the maximal effective doses. Similarly, in E the GH response to increasing doses of HEX (336.7 +/- 50.0 vs. 742.8 +/- 157.9 vs. 1205.1 +/- 178.1 micrograms/L/h, p < 0.05 for 1.0 vs. 2 micrograms/kg, p < 0.001 for 1.0 vs. 3.0 micrograms/kg and p < 0.03 for 2.0 vs. 3.0 micrograms/kg) and GHRH (183.8 +/- 27.3 vs. 260.9 +/- 17.3 vs. 356.1 +/- 46.3 micrograms/L/h, p < 0.005 for 1.0 vs. 3.0 micrograms/kg and p < 0.05 for 2.0 vs. 3.0 micrograms/kg) showed a progressive increase. In E the GH response to 3 micrograms/kg HEX or GHRH were clearly higher than those to 2 micrograms/kg. However, at each dose the GH responses to HEX or GHRH in E were lower (p < 0.05) than those in Y. In Y the GH response to HEX + GHRH was synergistical (4259.2 +/- 308.0 micrograms/L/h, p < 0.05). ARG strikingly potentiated the GHRH-induced GH rise (2640.8 +/- 273.6 micrograms/L/h, p < 0.01) but not the HEX-induced one (2371.7 +/- 387.2 micrograms/L/h) as well as the synergistical effect of HEX and GHRH (4009.1 +/- 360.8 micrograms/L/h). In E the GH response to HEX and GHRH was still synergistical (1947.7 +/- 306.0 micrograms/L/h, p < 0.05) but these responses were lower than those in young (p < 0.01). On the other hand, in E ARG restored the GH response to GHRH (1858.9 +/- 172.8 micrograms/L/h, p < 0.01) and even those to HEX (2069.5 +/- 528.7 micrograms/L/h, p < 0.01) and HEX + GHRH (4406.0 +/- 1079.2 micrograms/L/h, p < 0.05). Our present results indicate that the impairment of GHRP and GHRH receptor activity may have a role in the reduction of the somatotrope responsiveness in aging. However, the age-related reduction in the GH-releasing activity of GHRPs seems mainly dependent on age-related variations in the neural control, i.e. concomitant GHRH hypoactivity and somatostatinergic hyperactivity.

The insulin-like growth factor axis and plasma lipid levels in the elderly

The activity of the hypothalamic-GH-insulin-like growth factor (IGF) network declines with age. It has recently been shown that increased cardiovascular mortality occurs in adults with GH deficiency. As hypercholesterolemia is common in GH-deficient adults, and because there is experimental evidence that GH may play a role in regulating plasma cholesterol, we decided to investigate the activity of the GH-IGF axis in an elderly population by measuring serum IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) levels and to study their relationship with blood lipid levels. One hundred and thirty-two elderly subjects, 52 men and 80 women, were studied (age range, 60-91 yr). Men had significantly lower levels of IGFBP-3, high density lipoprotein cholesterol (HDL-C) and apoprotein A1 (ApoA1) compared to the women, whereas IGF-I and IGF-II were only slightly lower. Using linear regression analysis, we observed an inverse relationship of age with IGF-I (r = -0.35; P < 0.001), IGF-II (r = 0.40; P < 0.001), IGFBP-3 (r = 0.52; P < 0.001), body mass index, and lipid levels. Univariate regression analysis showed a strong and positive correlation of both IGF-I and IGFBP-3 with HDL-C and ApoA1. Partial correlation analysis, after adjustment for age and body mass index, showed that IGFBP-3 and IGF-II were still significantly and positively related to HDL-C and ApoA1. Furthermore, a strong association was documented among IGF-I, IGF-II, and IGFBP-3. These data demonstrate that even in an elderly population, further aging is accompanied by a progressive decline in circulating IGF-I, IGF-II, and IGFBP-3, suggesting a continuing diminution of the GH-IGF axis throughout aging. Moreover, the strong correlation between HDL-C and an index of GH secretion, such as IGFBP-3, suggests that GH might play an important role in lipid metabolism in healthy elderly subjects.

Functional consequences of the somatopause and its treatment

The decline in the function of the growth hormone-releasing hormone, growth hormone, insulin-like growth factor (GHRH-GH-IGF) axis has been termed the somatopause. Many of the catabolic sequelae seen in normal aging has been attributed to this decrease in circulating GH and IGF-I. In order to provide hormone replacement therapy for the somatopause, elderly subjects have been treated with GH, IGF-I, or both hormones together. Whereas numerous beneficial effects on body composition, strength, and quality of life have been reported in some studies, other studies have reported only marginal functional improvements. Moreover, it is clear that both hormones can cause significant morbidity.

Short-term administration of intranasal or oral Hexarelin, a synthetic hexapeptide, does not desensitize the growth hormone responsiveness in human aging

The function of the growth hormone-insulin-like growth factor I (GH-IGF-I) axis is reduced in aging, although the secretory capacity of somatotrope cells is preserved. Previous studies have suggested that continuous administration of GH-releasing peptides (GHRPs) results in homologous desensitization to the GH-releasing effect of the peptides. In the present study we have studied whether healthy elderly subjects would remain responsive to short-term, intermittent treatment with Hexarelin (HEX), a GHRP, and whether this treatment would result in an increase in serum IGF-I. In study I, the effect of an 8-day treatment with intranasal administration of 1.25 mg (about 18 micrograms/kg) t.i.d. HEX on the acute GH response to the hexapeptide and on serum IGF-I, IGF binding protein 3 (IGFBP-3), prolactin and cortisol levels was studied in seven elderly subjects (four males and three females, aged 67-80 years). In study II, the same parameters were studied before and after a 15-day treatment with oral administration of 20 mg (about 300 micrograms/kg) t.i.d. HEX in seven elderly women (aged 63-80 years). The GH response to the intranasal HEX administration was not significantly higher than that induced by 1 microgram/kg iv GHRH (229.4 +/- 35.9 vs 145.8 +/- 26.9 micrograms.l-1.h-1) and was maintained with a trend towards increase after an 8-day treatment with the peptide (342.5 +/- 199.3 micrograms.l-1.h-1). On the other hand, HEX treatment did not significantly modify IGF-I (138.7 +/- 11.1 vs 122.4 +/- 14.1 micrograms/l) but increased IGFBP-3 levels (2.4 +/- 0.2 vs 1.6 +/- 0.2 mg/l, p < 0.02). The GH response to the oral HEX administration was also not significantly higher than that to iv GHRH (257.6 +/- 72.0 vs 179.0 +/- 42.8 micrograms.l-1.h-1) and did not change after a 15-day treatment with the peptide (237.8 +/- 42.8 micrograms.l-1.h-1). Both IGF-I and IGFBP-3 levels were slightly but significantly increased by oral HEX treatment (156.0 +/- 10.7 vs 141.6 +/- 13.6 micrograms/l, p < 0.03, 3.4 +/- 0.2 vs 3.1 +/- 0.2 mg/l, p < 0.03, respectively). Neither intranasal nor oral HEX treatment modified PRL or cortisol levels and did not induce any side effect. In conclusion, these results indicate that chronic but intermittent treatment with HEX, administered either by intranasal or oral route, does not desensitize the GH response to the peptide. Moreover, after HEX treatment a trend towards increase was shown for IGF-I and IGFBP-3 levels. Thus, our findings strengthen the hypothesis that prolonged treatment with HEX may restore the reduced GH release in aging.

Effect of 15-day treatment with growth-hormone-releasing hormone alone or combined with different doses of arginine on the reduced somatotrope responsiveness to the neurohormone in normal aging

It is well known that both spontaneous and growth hormone-releasing hormone (GHRH)-stimulated GH secretion undergo an age-related decrease; in addition, there is supportive evidence that the GH hyposecretory state of aging is of hypothalamic origin. The aims of the study in 35 normal elderly subjects (20 males and 15 females aged 65-89 years) were to verify whether the low somatotrope responsiveness to GHRH (1 microgram/kg) can be primed by a daily GHRH treatment and whether the potentiating effect of both high intravenous (0.5 g/kg) and low oral (8 g) doses of arginine (ARG) on GH response to GHRH is maintained with time. In group A (N = 14) the GH response to GHRH on day 1 (AUC: 373.5 +/- 78.5 micrograms.l-1.h-1) was unchanged after 7 (3720 +/- 38 micrograms.l-1.h-1) and 15 days (377.9 +/- 63.8 micrograms.l-1.h-1) of daily GHRH administration. In group B (N = 6) the GH response to GHRH co-administered with iv ARG on day 1 (1614.2 +/- 146.2 micrograms.l-1.h-1) was higher (p < 0.05) than that of GHRH alone (group A) and persisted unchanged after 7 (1514.7 +/- 366.5 micrograms.l-1.h-1) and 15 days (1631.7 +/- 379.1 micrograms.l-1.h-1) of treatment. In group C (N = 15) the GH response to GHRH co-administered with oral ARG on day 1 (950.6 +/- 219.4 micrograms.l-1.h-1) was higher (p < 0.03) than that of GHRH alone (group A) but lower (p < 0.05) than that to GHRH plus iv ARG (group B).(ABSTRACT TRUNCATED AT 250 WORDS)

Low doses of either intravenously or orally administered arginine are able to enhance growth hormone response to growth hormone releasing hormone in elderly subjects

Reportedly, the responsiveness of somatotrope cells to GHRH is reduced in elderly humans but it is totally restored by arginine (ARG) which likely acts by inhibiting hypothalamic release of somatostatin. As this effect was observed after infusion of high doses of the amino acid, in this study, we compared the effect of iv administration of 30, 10 and 5 g ARG(group A, B and C, respectively) as well as oral administration of 8 g ARG(group D) on the GH response to 1 microgram/kg i.v.GHRH in 27 healthy elderly subjects (11 M and 16 F, age 70-86 yr, BMI 21-25 kg/m2). In group A (n = 7) 30 g i.v. ARG strikingly enhanced the GHRH-induced GH rise (peak, mean +/- SE: 41.5 +/- 4.4 vs 11.7 +/- 5.3 micrograms/L, p < 0.05). Similarly, in group B (n = 6) and D (n = 7) 10 g i.v. and 8 g oral ARG enhanced the GH response to GHRH (20.9 +/- 4.7 vs 8.3 +/- 2.8 micrograms/L, p < 0.03 and 31.0 +/- 5.3 vs 11.4 +/- 3.4 micrograms/L, p < 0.03, respectively). In contrast, in group C (n = 7) 5 g i.v. ARG failed to modify the GHRH-induced GH rise (6.0 +/- 1.6 vs 3.5 +/- 0.9 micrograms/L). The GH responses to GHRH alone did not significantly differ amongst groups; the GH responses to GHRH and ARG were not significantly different among groups A, B and D and were greater than the GH response in group C. These results show that the GH response to GHRH in elderly subjects is enhanced even by low iv doses of arginine and by the orally administered amino acid, the lowest effective dose being 8 g. Moreover, they imply that the combined administration of GHRH and arginine may be a useful approach to restore the impaired function of the GH-IGF axis in aging.

Growth hormone therapy in the elderly: implications for the aging brain

Growth hormone (GH) secretion declines during normal aging, resulting in lower serum insulin-like growth factor (IGF)-I levels. It has been proposed that many of the catabolic changes seen in normal aging, including osteoporosis and muscle atrophy, are in part caused by the decreased action of the GH-IGF-I axis. In addition, patients with GH deficiency have increased overall cardiovascular mortality. Several investigators have initiated GH treatment for elderly patients with relative hyposomatotropinemia. Initial reports suggest that GH can increase muscle mass, improve exercise tolerance, increase REM sleep and cause an enhanced sense of well-being. The basis for neuropsychiatric changes during GH therapy may be due to a direct CNS action of GH itself, to the increased IGF-I secretion which GH elicits, or to enhanced functioning of peripheral organ systems. Long-term studies will determine whether GH or IGF-I can exert a neurotrophic action in the aging brain.

Insulin-like growth factors (IGFs): implications for aging

The insulin-like growth factors (IGF)-I and IGF-II are peptides with structural homology to insulin and potent mitogenic and anabolic actions in vitro and in vivo. IGF-I levels are growth hormone (GH)-dependent and vary strikingly with age. IGF-I levels are typically low in infancy and childhood, increase dramatically during puberty, and then gradually decline with advancing age. Whether age-associated changes in GH production or sex steroid secretion, or other unknown factors, cause diminished IGF production in the elderly remains to be determined. In the brain, IGF-II appears to be the most prevalent IGF, but a truncated form of IGF-I also has been recognized. IGF actions are mediated by binding to a family of receptors, which includes the insulin receptor, the structurally homologous type I IGF receptor, and the IGF-II/M-6P receptor, all of which are found in the central nervous system. Additionally, the IGFs bind with high affinity to a family of IGF-binding proteins (IGFBPs). Of the six known IGFBPs, IGFBP-2 appears to be the major one in the mammalian brain and is a major component of CSF. Immunoreactive IGFBP-2 has been identified in astrocytes, and its mRNA has been identified in fetal and adult brain and choroid plexus. The IGFBPs transport the IGFs in serum and other body fluids and appear to regulate IGF access to receptors. In vivo regulation of IGFBPs includes tissue-specific proteases, which cleave specific IGFBPs, altering their affinities for IGF peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of insulin-like growth factor-binding protein expression by thyroid hormone in rat GH3 pituitary tumor cells

Rat pituitary GH3 tumor cells express GH and insulin-like growth factor-I (IGF-I) mRNAs and possess specific IGF-I and IGF-II receptors which mediate the inhibitory effect of IGF on GH secretion. T3 increases the rate of cell replication and GH gene transcription, and causes an increase in IGF-I binding to cell membranes. Since the IGFs circulate in association with specific binding proteins (IGFBPs) that appear to modulate the access of IGFs to their receptors, we have investigated the effect of T3 treatment on the expression of IGFBPs in GH3 cells. Cells were grown in serum-free defined medium, and IGFBP secretion was determined by Western ligand blotting of conditioned medium after the addition of T3 and/or various peptides for 48-72 h. The conditioned medium of GH3 cells revealed a complex of bands migrating at 40-45 Mr, a pattern typical of rat (r) IGFBP-3. T3 treatment resulted in an increase in rIGFBP-3. IGF-I, IGF-II, and insulin did not alter rIGFBP-3 levels. After concentrating (10-fold) conditioned medium samples, two additional bands at 24K and 28K mol wt were also seen. These bands corresponded in size to rIGFBP-4 (24K) and its glycosylated form (28K). The mRNAs for both rIGFBP-3 and rIGFBP-4 were present in GH3 cells; T3 treatment increased steady state levels of rIGFBP-3 mRNA, but did not affect BP-4 mRNA levels. To learn whether the increased expression of IGFBPs could be responsible for the increased IGF-I binding seen after T3 treatment, [125I]IGF-I was cross-linked to GH3 membranes, and the proteins were separated on a 5-15% gradient sodium dodecyl sulfate-polyacrylamide gel under reducing conditions. T3 treatment induced a large increase in the intensity of bands migrating at 135K and 280K, representing the alpha-subunit of the IGF-I receptor and an incompletely reduced alpha-alpha-dimer, respectively. No membrane-associated IGFBPs were detected. In conclusion, GH3 cells express two IGFBPs, rIGFBP-3 and rIGFBP-4, which are differentially regulated by T3. The increased binding of IGF-I to GH3 cell membranes after T3 treatment indicates that thyroid hormone induces an up-regulation of IGF-I receptors and that the increased IGF-I binding to GH3 membranes is not due to increased expression of membrane-associated IGFBPs.

alpha-Glycerylphosphorylcholine administration increases the GH responses to GHRH of young and elderly subjects

Growth hormone (GH) secretion is decreased during aging in humans and in rodents. This decrease may be due to increased hypothalamic somatostatin release, which is inhibited by cholinergic agonists, or to decreased secretion of GHRH. Alpha-glyceryl-phosphorylcholine (alpha-GFC) is a putative acetylcholine precursor used in the treatment of cognitive disorders in the elderly. In order to learn what effect alpha-GFC had on GH secretion, GH-release hormone (GHRH) was given to young and old human volunteers, with or without the addition of alpha-GFC. GH secretion was greater in the younger subjects than in the old individuals, and both groups had a greater GH response to the GHRH+alpha-GFC than to GHRH alone. The potentiating effect of alpha-GFC on GH secretion was more pronounced in the elderly subjects. These findings confirm the observation that aged individuals respond less well to GHRH than younger subjects, and provides further evidence that increased cholinergic tone enhances GH release.

Differential effects of insulin-like growth factor (IGF)-I and IGF-II on the expression of IGF binding proteins (IGFBPs) in a rat neuroblastoma cell line: isolation and characterization of two forms of IGFBP-4

The isolation and hormonal regulation of two low molecular weight insulin-like growth factor binding proteins (IGFBPs) present in the conditioned medium (CM) of the rat neuroblastoma cell line B104 cells has been performed. IGFBPs were purified by ZnSO4 precipitation, insulin-like growth factor-I 1IGF-I) affinity chromatography, and reverse phase HPLC. Final isolation and N-terminal analysis was accomplished by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotting to polyvinylidene difluoride membranes, and sequencing of the bound proteins. Two IGFBPs, with apparent Mr of 28K and 24K were coisolated and sequenced. Both proteins had identical N-terminal sequences and appear to be two forms of IGFBP-4. Treatment of the IGFBPs with endoglycosidase-F caused a shift in the apparent Mr of the 28K IGFBP to 24K. However, there was no change in the apparent Mr of the 24K IGFBP. The data from this study suggest that the IGFBP-4 exists as both a glycosylated and nonglycosylated protein. Treatment of B104 cells with IGF-I increased the expression of both the 24K and 28K IGFBPs and also resulted in the appearance of IGFBP-3 and an unknown IGFBP at 29K. When added to subconfluent cells, IGF-I was also mitogenic in B104 cells. Similar to IGF-I, IGF-II treatment increased cell number and resulted in the appearance of IGFBP-3 and the 29K IGFBP. However, IGF-II treatment resulted in a significant decrease (approximately 50%) in the 24K IGFBP and also decreased the 28K IGFBP. This decrease in the expression of the 24K and 28K IGFBPs was dose-dependent and was blocked by addition of IGF-I to the cells. When an IGF-II receptor antibody was added to the cells it mimicked the effects of IGF-II on B104 cells, suggesting that the inhibitory effects of IGF-II are mediated through the type II IGF receptor. Although both IGF-I and IGF-II affected the amount of the 24K IGFBP in the CM, neither peptide affected the expression of the messenger RNA for the 24K IGFBP. In conclusion, we have isolated two IGFBPs from the CM of B104 cells. Both the 24K and 28K IGFBPs appear to be isoforms of the same protein, and sequence data suggest these proteins are two forms of IGFBP-4. IGF-I increases the expression of both of these IGFBPs, whereas IGF-II decreases their expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of cytidine 5'-diphosphocholine administration on basal and growth hormone-releasing hormone-induced growth hormone secretion in elderly subjects

The basal and GH-releasing hormone-stimulated secretion of GH declines in the elderly. We tested the ability of cytidine 5'-diphosphocholine, a drug used in the treatment of stroke and Parkinson's disease, to alter GH secretion in 11 healthy elderly volunteers, aged 69-84. Each subject received an iv infusion of 2 g of cytidine 5'-diphosphocholine or normal saline. GHRH and TRH were also administered during cytidine 5'-diphosphocholine infusions. The infusion of cytidine 5'-diphosphocholine induced a 4-fold (p less than 0.05) increase in serum GH levels over basal values. A small increase in GH was seen after GHRH administration. However, the addition of GHRH to the cytidine 5'-diphosphocholine infusion resulted in a GH response which was significantly greater than that seen after GHRH alone; the integrated concentration of GH was more than 2-fold greater in the cytidine 5'-diphosphocholine treated group (706.85 +/- 185.1 vs 248.9 +/- 61.4 micrograms.l-1.(120 min)-1; p = 0.01). The PRL and TSH responses to TRH were not significantly affected by cytidine 5'-diphosphocholine infusion, indicating that dopaminergic mechanisms are not involved. These studies demonstrate that cytidine 5'-diphosphocholine can enhance basal and GHRH-stimulated GH release in the elderly, but the mechanism of action of the drug remains unclear.

The effects of aging on the secretion of the common alpha-subunit of the glycoprotein hormones in men

To investigate the effects of aging on the secretion of the common alpha-subunit of the glycoprotein hormones, we measured basal levels of luteinizing hormone (LH), testosterone (T) and alpha-subunit in 176 normal men aged 19 to 89 years. In addition, in two groups of young (less than 65 years; n = 25) and old (greater than 65 years; n = 15) subjects, the effects of luteinizing hormone-releasing hormone (LHRH) on LH and alpha-subunit secretion were determined. Age-related increases in serum alpha-subunit and LH were noted only in the oldest men while T levels decreased progressively with advancing age. LHRH stimulation resulted in significantly greater secretion of alpha-subunit in the old subjects while no difference in LH release between young and old men was observed. Moreover, there was a delay to peak LH and alpha-subunit levels after LHRH in the old subjects. These data suggest that the aging process in males involves deficits in both testicular and gonadotroph functions as demonstrated by (1) the relative hypogonadotropic hypogonadism seen until the ninth decade; (2) the hypergonadotropic hypogonadism apparent in men greater than 80 years; (3) the delay in the timing of peak responses of LH and alpha-subunit after LHRH administration; and (4) the disproportionate increase in the secretion of alpha subunit relative to intact LH.

Dissociated effect of buserelin on luteinizing hormone (LH) and alpha subunit in men

Chronic treatment with LHRH analogs is known to depress testosterone (T) values to castration levels. In contrast to results from animal experiments, studies in humans indicate that a pituitary-dependent mechanism predominates in the suppression of plasma T. However, this reduction in T levels may occur when LH values are within or below the normal range. One explanation for this result has been that while absolute values of LH in serum may not change, the bioactivity of LH is reduced. The present study has been performed to determine whether this discrepancy between LH and T values is obscured by the hypersecretion of the alpha-subunit which is devoid of any biological activity but crossreacts in most RIAs with LH. Following 2 days of blood collection to establish basal serum hormone levels, six men with prostatic cancer were treated with the LHRH agonist, Buserelin (500 micrograms sc, daily injection) for 15 days. The most significant endocrine responses at the end of this treatment were as follows: 1) T levels were depressed to the castration range; 2) no change was seen in the LH values with a conventional RIA procedure which crossreacted with the alpha-subunit; 3) a significant decrease was found in the LH values evaluated with an immunoradiometric (IRMA) method, which shows no cross-reactivity with the alpha-subunit; 4) there was a significant increase in the alpha-subunit levels; and 5) serum FSH levels were significantly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Secretion of alpha-subunit and intact gonadotropins after surgical and chemical castration

In order to investigate the regulatory mechanisms involved in the secretion of glycoprotein hormones, we studied the secretory patterns of LH, FSH and alpha-subunit in hypogonadal men. Three groups of patients with carcinoma of the prostate were studied both before and 15 days after orchiectomy, or the initiation of ketoconazole or LHRH analog therapy. There were significant increases (P less than 0.01) in LH and alpha-subunit levels in the patients treated with orchiectomy and ketoconazole, but FSH levels increased only in the orchiectomized patients. After LHRH analog treatment, LH levels were significantly decreased when assayed with an immunoradiometric assay method which does not cross-react with alpha-subunit. FSH values were significantly lower than pretreatment levels, while alpha-subunit levels remained significantly elevated throughout the study period. These results demonstrate that after both chemical (ketoconazole) and surgical castration, the secretion of alpha subunit follows a pattern which is tightly correlated with that of LH but not of FSH. However, after LHRH analog treatment, alpha-subunit appears to be the sole secretory product of the gonadotroph.

Triiodothyronine regulates insulin-like growth factor-I binding to cultured rat pituitary cells

Abstract Triiodothyronine (T(3)) stimulates the synthesis of growth hormone and enhances the growth of neoplastic rat pituitary somatomam-motrophs (GH cells) in culture. Moreover, T(3) has been shown to stimulate the production and secretion of an autocrine growth factor by these cells. We have previously demonstrated the presence of specific receptors for insulin-like growth factors (IGF) on GH cells. Since GH(3) cells contain mRNA encoding IGF-I, it has been suggested that IGF-I might act in an autocrine fashion in these cells. Therefore, it was of interest to learn how T(3) affects IGF-I binding to GH(3) cells. T(3) increased [(125)I]IGF-I binding in a time - and dose-dependent manner. After 48 h of exposure to T(3), an increase in IGF-I binding was seen with 10(-11)M T(3), maximizing with 10(-8)M T(3). When cells were exposed to 10(-8) T(3), [(125)I]IGF-I binding reached a maximum of 218 +/- 20.8% of control (+/-SEM, P < 0.002) after 72 h of incubation. Scatchard analysis indicated that T(3) did not alter the K(d) of IGF-I for its receptor, but that the total receptor number was increased. Dexamethasone (10(-7)M) inhibited the T(3)-induced increase in IGF-I binding, but glucocorticoid alone did not substantially alter receptor number. No significant change in insulin or IGF-II binding was seen after hormone treatment. 10(-8) M T(3) or IGF-I increased the growth of the GH(3) cells by >/=30%. Our data indicate that T(3) upregulates IGF-I binding in GH(3) cells without altering insulin binding and thereby provides a means for enhancing potential autocrine regulation in this cell line.

Calcitonin inhibition of growth hormone-releasing hormone-induced GH secretion in normal men

Calcitonin has been shown to modulate pituitary hormone secretion in a variety of ways. In this study we examined the effects of a salmon calcitonin infusion on GHRH-induced GH secretion in 5 normal men. In addition, in vitro experiments were performed using primary cultures of rat anterior pituitary cells in order to examine whether there is a direct pituitary effect of CT. Infusion of CT significantly blunted the GH response to GHRH in all subjects without affecting basal GH secretion or plasma calcium levels. Infusion of CT was accompanied by significant increases in ACTH, beta-endorphin, cortisol and free fatty acid levels, and by a significant decrease in serum insulin levels. The addition of CT to primary cultures of rat pituitary cells did not alter basal or stimulated secretion of GH or ACTH. These results indicate that: 1) CT blunts the GH response to GHRH; 2) CT infusion results in the stimulation of the hypothalamic-pituitary-adrenal axis, and 3) this effect is probably exerted at the hypothalamic level, since no direct activity of CT was documented in vitro on either GH or ACTH secretion.