Effects of acute and chronic starvation on central and peripheral noradrenaline turnover, blood pressure and heart rate in the rat

Abstract

summaryWhen faced with stress, an organism calls upon several mechanisms to maintain biological homeostasis. The cardiovascular system is the first to respond usually with an increase in arterial pressure and tachycardia. Therefore we investigated the central and peripheral sympathetic responses to acute and chronic starvation in Wistar rats. The noradrenaline (NA) turnover rate was determined in different catecholaminergic nuclei (A1, A2, A5, A6) as well as the arterial blood pressure and heart rate modifications. During acute starvation (3 days of starvation), the NA turnover was increased in the A1 and rostral A2 nuclei as well as in ventricles and kidneys and decreased in the A6 nucleus. During chronic starvation (4 consecutive cycles of 3 days of starvation plus 1 day of feeding), the NA turnover was increased in the A5 and caudal A2 nuclei as well as in ventricles and atria and decreased in the A1 nucleus and kidneys. The arterial blood pressure revealed a gradual decrease during the first 3 days of fasting but the heart rate was not modified. We conclude that starvation should be considered as an unusual state of stress because of the absence of locus coeruleus response (A6 nucleus) despite its well-defined role in stress reactions. One of the manifestations of these central and peripheral noradrenergic changes is the change in blood pressure during the starvation-feeding cycles.introduction When faced with stress, an organism calls upon several different mechanisms in an attempt to maintain biological homeostasis. The response of the 'fight or flight' reaction includes a vegetative component which permits the organism to optimize its reaction to these adverse conditions. The manifestations of this system are multiple. The cardiovascular system is the first to respond, associated with an increase in arterial pressure and tachycardia. In addition, there is immediate or deferred secretion of several hormones, most notably the hormones of the hypothalamic-pituitary-adrenal axis such as catecholamines and corticoids. Many forms of stress can induce these responses. These include immobilization, cold, haemorrhage, hypoglycaemia resulting in insulin injection ), hypoxia (Elam et al. 1981 and psychosocial stress (Ely, 1995).Our previous studies have shown that starvation constitutes a stressful condition in rats, resulting in an activation of the pituitary-adrenal cortex axis (El Fazaâ, 1983). Since the

The effect of camel milk curd masses on rats blood serum biochemical parameters: Preliminary study

“…Another critical variable could be the animal’s age, with younger rats losing a more significant percentage of body weight than older rats. This was described in research work [ 45 ], where more immature rats lost 29% of body weight in 24 h of deprivation of food. Therefore, we assume that our weight loss data do not exceed the allowable weight loss limit set by the regulatory body and the animal ethics committee.…”

Chronic repeated restraint stress increases prolactin‐releasing peptide/tyrosine‐hydroxylase ratio with gender‐related differences in the rat brain

“…PrRP expression increased in males in both cell groups, but this happened to a smaller extent in the A2 than in the A1 neurons. The A1 and A2 cells react to chronic stress in a stressor kind and strength‐specific way (El Fazaa et al. 1999; Pacak 2000; Li et al.…”

Participation of β-adrenergic activity in modulation of GLUT4 expression during fasting and refeeding in rats

“…Although acute starvation had been considered as a state of stress [23], it is important to point out that increased sympathetic activity has not been observed in several tissues when evaluated by methods such as catecholamine turnover rate analysis, microdialysis, or microneurography. In contrast, fasting-induced decrease in the sympathetic outflow has been reported in BAT [24,25], heart [24,26], pancreas and liver [27], kidney [28], and skeletal muscle [29].…”