Aging and urinary vasopressin excretion in healthy men

Therapeutic potential of vasopressin in the treatment of neurological disorders

Vasopressin (VP) is a nonapeptide made of nine amino acids synthesized by the hypothalamus and released by the pituitary gland. VP acts as a neurohormone, neuropeptide and neuromodulator and plays an important role in the regulation of water balance, osmolarity, blood pressure, body temperature, stress response, emotional challenges, etc. Traditionally VP is known to regulate the osmolarity and tonicity. VP and its receptors are widely expressed in the various region of the brain including cortex, hippocampus, basal forebrain, amygdala, etc. VP has been shown to modulate the behavior, stress response, circadian rhythm, cerebral blood flow, learning and memory, etc. The potential role of VP in the regulation of these neurological functions have suggested the therapeutic importance of VP and its analogues in the management of neurological disorders. Further, different VP analogues have been developed across the world with different pharmacotherapeutic potential. In the present work authors highlighted the therapeutic potential of VP and its analogues in the treatment and management of various neurological disorders.

Do screening blood pressure and plasma catecholamines predict development of hypertension? Twenty-year follow-up of middle-aged men

OBJECTIVES

The sympathetic nervous system is implicated in the development and maintenance of hypertension. However, the predictive impact of arterial plasma catecholamines has never been reported. We investigated arterial catecholamines and blood pressures (BPs) prospectively over 20 years in a group of well-characterized middle-aged men.

METHODS

Fifty-six of original 79 men were available for the follow-up. Multiple regression analysis was done with mean BP at follow-up as a dependent variable, and arterial plasma catecholamines and BP at baseline as independent variables.

RESULTS

Half of the originally normotensive men developed hypertension during follow-up. There were significant differences in the screening BP values measured at baseline between the new hypertensives and the sustained normotensives. Multiple regression analysis revealed arterial adrenaline at baseline as an independent predictor of mean BP at follow-up in the new hypertensives (beta = 0.646, R2 = 0.42, p = 0.007). Furthermore, arterial noradrenaline at baseline was a negative independent predictor of mean BP at follow-up in the sustained normotensives (beta = -0.578, R2 = 0.334, p = 0.020). Noradrenaline increased with age in the group as a whole (1318+/-373 vs 1534+/-505 pmol/l, p = 0.010) while adrenaline did not change.

CONCLUSION

Our data suggest that arterial adrenaline is involved in the development of hypertension over 20 years in middle-aged men. Men with sustained normotension may have an inherent protection against sympathetic overactivity. Furthermore, screening BP at baseline in normotensive men differentiated between those who developed hypertension and those who remained normotensive at follow-up.

Arterial plasma noradrenaline predicts left ventricular mass independently of blood pressure and body build in men who develop hypertension over 20 years

BACKGROUND

Increased sympathetic activity may be an underlying mechanism in cardiovascular disease. It has been hypothesized that the degree of left ventricular (LV) hypertrophy is partly related to the blood pressure level, and partly to neurohormonal factors. The aim of this study was to investigate predictors of LV mass, including arterial plasma noradrenaline as an index of sympathetic activity, with particular emphasis on subjects who developed hypertension over a period of 20 years.

METHODS

In a 20-year prospective study of middle-aged men, sustained hypertensives (n = 22), new hypertensives (crossovers) (n = 17) and sustained normotensives (controls) (n = 17) were examined both at baseline and after 20 years of follow-up (at ages 42.1 +/- 0.5 and 62.3 +/- 0.6 years, respectively). Relationships between arterial plasma catecholamines, blood pressure and body mass index at baseline to left ventricular parameters by echocardiography at follow-up were investigated.

RESULTS

Groups were homogeneous regarding age, gender, race and body build. The group of sustained hypertensives had significantly more LV hypertrophy (P = 0.025) and diastolic dysfunction (P = 0.010). Among the crossovers, LV mass index was positively correlated to arterial plasma noradrenaline (r = 0.50, P = 0.043) and body mass index (BMI) (r = 0.51, P = 0.039) and showed a positive trend with systolic blood pressure (SBP) at baseline. Arterial plasma noradrenaline (beta = 0.47) was found to predict LV mass index after 20 years independently of BMI (beta = 0.45) and SBP (beta = 0.22) at baseline (R adjusted = 0.345, P = 0.037). Such a relationship was not found in the controls or in the sustained hypertensives, of which 16 were treated with antihypertensive drugs.

CONCLUSIONS

Arterial plasma noradrenaline at baseline, as an index of sympathetic activity, predicts LV mass at follow-up independently of systolic blood pressure and body build in middle-aged men who developed hypertension over a period of 20 years.

Physiologic aspects of aging: impact on cancer management and decision making, part I

A gradual diminution in the physiologic reserve or functional capacity over time is the characteristic hallmark of aging, and this has a direct impact on the choice of cancer therapy and its toxicity profile in elderly patients with cancer. With the expected rapid rise of the older population as a subgroup, oncologists will increasingly treat elderly patients. Provision of competent care to this increasing pool of older patients with cancer necessitates that oncology professionals become familiar with age-associated changes in organ physiology and their impact on cancer treatment and toxicity. In this comprehensive review, we have listed changes in cardiovascular, gastrointestinal, pulmonary, and renal physiology with aging. Also enumerated is the impact of these changes on cancer therapy and toxicity in each organ system-based section. Cardiovascular changes primarily lead to reduction of the cardiac functional reserve, with a consequent increase in the risk of congestive heart failure. Changes in gastrointestinal physiology lead to increased mucosal damage. A reduction in pulmonary reserve has implications for postradiation complications, and a decline in renal function leads to an increased potential for nephrotoxicity. These changes impair the ability of older patients with cancer to tolerate cancer therapy and increase their risk of toxicities. This may lead to an overall decline in functional status, resulting frailty, poor quality of life, and ultimately poor outcomes. Becoming familiar with age-related physiologic changes is the first step for oncologists seeking to better tailor their treatments. This, combined with adoption of some of the clinical interventions suggested in this review, can help better manage the geriatric oncology patient. Further research is necessary for the development of more specific evidence-based recommendations.

Neurohypophyseal peptides in aging and Alzheimer's disease

The neurohypophyseal hormones arginine-vasopressin (AVP) and oxytocin (OT) are produced in the neurons of the hypothalamic supraoptic (SON) and paraventricular (PVN) nucleus and in the much smaller cells of the suprachiasmatic (SCN) nucleus. The SON is the main source of plasma AVP. Part of the AVP and OT neurons of the PVN join the hypothalamo-neurohypophyseal tract, whereas others send projections to the median eminence or various brain areas, where AVP and OT are involved in a number of central functions as neurotransmitters/neuromodulators. AVP and OT from the PVN can also regulate via the autonomous innervation endocrine glands and fat tissue. OT is produced for a major part in the PVN but some OT neurons are present in the SON. Moreover, both AVP and OT containing neurons are observed in the "accessory nuclei", i.e. islands situated between the SON and PVN. The SCN is the biological clock, and the number of AVP expressing neurons in the SCN shows both diurnal and seasonal rhythms. In addition to these hypothalamic areas, AVP and OT may be found to a lesser extent in some other brain areas, such as the bed nucleus of the stria terminalis, diagonal band of Broca, nucleus basalis of Meynert, lateral septal nucleus, globus pallidus and the anterior amygdaloid nucleus, as well as in the peripheral tissues. The AVP and OT containing neurons should not be considered as one system. Prominent functional differences exist between the different nuclei. The heterogeneity also becomes clear from the marked differences in the neurohypophyseal peptides containing neurons of the SON, PVN and SCN during aging, and in the most prevalent age-related neurodegenerative diseases, i.e. Alzheimer's disease (AD). For those reasons, we will discuss the SON, PVN and SCN separately.

Age-associated changes in interferon-gamma and interleukin-4 secretion by purified human CD4+ and CD8+ T cells

Aging is associated with a decline in immune function. Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), two important immune deviation-related cytokines, are mainly produced by type 1 and type 2 T cells, respectively. To investigate the age-associated changes in the secretion of these two cytokines, 20 elderly and 20 young subjects fulfilling the SENIEUR protocol were enrolled. The ratios of CD4+ to CD8+ T cells were not different between the two age groups. The CD4+ and CD8+ T cells were purified by a magnetic cell sorting system, and then activated by concurrent anti-CD3 and anti-CD28 stimulation. The released cytokines were determined by ELISA. Both the CD4+ and the CD8+ T cells of the elderly individuals secreted a significantly larger amount of IFN-gamma after activation. Profound IL-4 production by CD8+ T cells was observed in the older subjects compared with that of the young subjects. These data suggested that age-associated decrease in immunity may be related to an imbalance in the secretion of immune deviation cytokines. The number of IL-4-secreting CD8+ T cells (T cytotoxic 2) rose significantly in the older individuals. Our design also provided a useful way to differentiate the T cell subsets secreting the same cytokine, such as IFN-gamma-producing T helper 1 and T cytotoxic 1 cells.

Dehydration induces Fos, but not increased vasopressin mRNA in the supraoptic nucleus of aged rats

Dehydration induces Fos expression and increases the length of the vasopressin (VP) mRNA poly-A tail and the content of VP mRNA in the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus. The current studies were performed to evaluate the effect of aging on these responses. Fischer 344 rats of 4, 14, and 28-30 months of age were either water deprived for 72 h or allowed ad libitum access to water. Fos induction in the SON and PVN was examined by immunocytochemistry in order to provide an index of cellular activation. VP mRNA content and size was examined in SON by Northern analysis as an index of VP synthetic capacity. Dehydration induced the expected increase in plasma osmolality in all three ages, however, serum VP was only increased in the 4- and 14-month-old rats. The increase in serum VP was accompanied by a decrease in VP content of the posterior pituitary (PP) in the dehydrated 4- and 14-month-old rats. PP VP content was reduced in both the hydrated and dehydrated old rats relative to the other ages (P = 0.0007). Fos was induced in both SON and PVN of all water deprived rats regardless of age. The density of Fos staining was increased in both nuclei following dehydration (SON, P = 0.002; PVN, P = 0.0001). There was also a significant increase in the number of cells expressing Fos in both nuclei in the dehydrated animals (SON, P = 0.002; PVN, P = 0.0056). There was no significant effect of age on the density of Fos staining. In contrast, dehydration failed to elicit the expected increase in VP mRNA size and content in the SON of the aged dehydrated rats although both of these parameters were increased in the 4- and 14-month-old rats (P < 0.05). Thus, the inability of old Fischer rats to increase serum VP during chronic dehydration is not caused by decreased activation of the neurons (as indicated by Fos induction), but apparently reflects depletion of PP stores of VP due to an inability to increase the amount of VP mRNA available for translation.

Vasopressin in aged rats: longitudinal studies of vasopressin excretion in Sprague-Dawley and Fischer 344 strains

In order to provide physiological baseline values for future experimental procedures, indices of vasopressin secretion were assessed in male Sprague-Dawley (SD) and Fischer 344 (F344) rats at 3 and 20 months of age. Daily water intake, urine volume, urine osmolality, and urinary vasopressin excretion were monitored in SD rats for 30 days, and in F344 rats for 60 days. In the SD strain, daily water and urine volumes, expressed as ml/24 hr/100 g b.wt., were consistently lower in aged animals, as was a calculation of water balance (water intake-urine output volumes/24 hr). Although mean VP concentration in urine appeared higher in aged rats (33.9 +/- 20.4 pg/ml) than in young (16.3 +/- 7.7 pg/ml), total daily VP excretion was comparable for both ages when expressed as a function of body weight [80.6 +/- 37.3 pg for 3 months old (m.o.) and 81.9 +/- 47.2 pg/24 hr/100 g b.wt. for 3 and 20 m.o. respectively]. Young and old F344 males showed comparable daily drinking and urine volumes, and water balance, during two months of monitoring, but VP excretion was lower (p less than 0.025) in aged rats (83.8 +/- 19.0 pg/24 hr/100 g b.wt.) than in 3 m.o. rats (213.0 +/- 48.1 pg/24 hr/100 g b.wt.). Urine VP concentration was comparable (69.6 +/- 20.6 for 3 m.o.; 59.8 +/- 25.6 pg/ml for 20 m.o.). Mean urine osmolality was not significantly different among groups. Urine osmolality and daily urine volumes showed a significant correlation with daily VP excretion among young, but not aged, rats of both strains.(ABSTRACT TRUNCATED AT 250 WORDS)