Anabolic steroid excess promotes hydroelectrolytic and autonomic imbalance in adult male rats: Is it enough to alter blood pressure?

AIM: The present study investigated the effects of anabolic steroid (AS) excess on blood pressure regulation. METHODS: Male Wistar rats were treated with nandrolone decanoate (AS) or vehicle (CTL) for 8 or 10 weeks. Saline (1.8%) and water intake were measured in metabolic cages. Urinary volume, osmolarity, Na+ and K+ concentrations, and plasma osmolarity were measured. The autonomic balance was estimated by heart rate variability at baseline or after icv injection of losartan. Cardiac function was assessed by echocardiography and ex vivo recordings. Myocardial collagen deposition was evaluated by Picrosirius-Red staining. Vascular reactivity and wall thickness were investigated in aortic sections. Blood pressure (BP) was assessed by tail-cuff plethysmography. Angiotensin II type I receptor (AT1R), renin, and mineralocorticoid receptor (MR) mRNA expression was measured in the kidneys and whole hypothalamus. RESULTS: AS group exhibited decreased urinary volume and Na+ concentration, while urinary K+ concentration, plasma osmolarity, and renal AT1R and renin mRNA levels were increased compared to CTL (p < 0.05). Water intake was increased, and saline intake was decreased in the AS group (p < 0.01). AS group exhibited increased low-frequency/high-frequency-ratio, while it was decreased by icv injection of losartan (p < 0.05) compared to baseline. Neither cardiac function nor vascular reactivity/morphology was affected by AS excess (p > 0.05). Ultimately, BP levels were not altered by AS excess (p > 0.05). CONCLUSION: AS excess promoted hydroelectrolytic and autonomic imbalance but did not alter vascular or cardiac function/morphology.

Administration of an anabolic steroid during the adolescent phase changes the behavior, cardiac autonomic balance and fluid intake in male adult rats.

Few data are available on adolescent users because most behavioral studies on anabolic-androgenic steroids (AAS) abuse have been performed in adults. Studies evaluating the impact of long-term effects of AAS abuse on the prepubertal phase are even more uncommon. Accordingly, this study was developed to test the hypothesis that changes induced by the use of AAS during the adolescent phase may be noted in the adult phase even when the AAS treatment cycle is discontinued. Therefore, not only behavioral changes but also possible autonomic and electrolyte disorders were evaluated. For this purpose, we used male prepubertal, 26-day-old (P26) Wistar rats that were treated with vehicle (control, n=10) or testosterone propionate (TP; 5 mg/kg intramuscular (IM) injection, AAS, n=10) five times per week for 5 weeks, totaling 25 applications during the treatment. Aggression tests were performed at the end of the cycle (P54-56), whereas open-field tests (OFTs), elevated plus maze (EPM) behavioral tests and measurements of heart rate variability (HRV), fluid intake and pathology were conducted in the adult phase (P87-92). The AAS group showed greater aggressiveness in the pubertal phase and higher levels of horizontal and vertical exploration and anxiety-related behavior in the adult phase than the control group (P<0.05). HRV tests showed an increase in sympathetic autonomic modulation, and hydroelectrolytic assessment showed lower basal intake levels of hypertonic saline than the control group (P<0.05), without statistically significant changes in the basal intake of water. These data together suggest that the use of AAS during the prepubertal phase induces behavioral, autonomic and hydroelectrolytic changes that manifest in the adult phase even when treatment is discontinued in late adolescence in rats.

Noninvasive method for electrocardiogram recording in conscious rats: feasibility for heart rate variability analysis.

Heart rate variability (HRV) analysis consists in a well-established tool for the assessment of cardiac autonomic control, both in humans and in animal models. Conventional methods for HRV analysis in rats rely on conscious state electrocardiogram (ECG) recording based on prior invasive surgical procedures for electrodes/transmitters implants. The aim of the present study was to test a noninvasive and inexpensive method for ECG recording in conscious rats, assessing its feasibility for HRV analysis. A custom-made elastic cotton jacket was developed to fit the rat's mean thoracic circumference, with two pieces of platinum electrodes attached on its inner surface, allowing ECG to be recorded noninvasively in conscious, restrained rats (n=6). Time- and frequency-domain HRV analyses were conducted, under basal and autonomic blockade conditions. High-quality ECG signals were obtained, being feasible for HRV analysis. As expected, mean RR interval was significantly decreased in the presence of atropine (p <0.05) and increased in the presence of propranolol (p<0.001). Also, reinforcing the reliability of the method, low- and high-frequency HRV spectral powers were significantly decreased in the presence of propranolol (p <0.05) and atropine (p< 0.001), respectively. In summary, the present work describes a novel, inexpensive and noninvasive method for surface ECG recording in conscious rats.

Noninvasive method for electrocardiogram recording in conscious rats: feasibility for heart rate variability analysis

Heart rate variability (HRV) analysis consists in a well-established tool for the assessment of cardiac autonomic control, both in humans and in animal models. Conventional methods for HRV analysis in rats rely on conscious state electrocardiogram (ECG) recording based on prior invasive surgical procedures for electrodes/transmitters implants. The aim of the present study was to test a noninvasive and inexpensive method for ECG recording in conscious rats, assessing its feasibility for HRV analysis. A custom-made elastic cotton jacket was developed to fit the rat's mean thoracic circumference, with two pieces of platinum electrodes attached on its inner surface, allowing ECG to be recorded noninvasively in conscious, restrained rats (n=6). Time- and frequency-domain HRV analyses were conducted, under basal and autonomic blockade conditions. High-quality ECG signals were obtained, being feasible for HRV analysis. As expected, mean RR interval was significantly decreased in the presence of atropine (p <0.05) and increased in the presence of propranolol (p<0.001). Also, reinforcing the reliability of the method, low- and high-frequency HRV spectral powers were significantly decreased in the presence of propranolol (p <0.05) and atropine (p< 0.001), respectively. In summary, the present work describes a novel, inexpensive and noninvasive method for surface ECG recording in conscious rats.

A análise da variabilidade da freqüência cardíaca (VFC) consiste em uma metodologia bem estabelecida para o estudo do controle autonômico cardíaco, tanto em humanos como em modelos animais. As metodologias convencionais para o estudo da VFC em ratos utilizam-se de procedimentos cirúrgicos para o implante de eletródios ou transmissores, o que possibilita a posterior aquisição do eletrocardiograma (ECG) no estado consciente. O objetivo do presente trabalho foi o de desenvolver e aplicar um método não-invasivo para o registro do ECG em ratos conscientes, verificando sua validade para a análise da VFC. Uma vestimenta de tecido elástico em algodão foi desenvolvida de acordo com as dimensões médias da circunferência torácica dos animais, e dois pequenos eletródios retangulares de platina foram aderidos à superfície interna da vestimenta, permitindo o registro do ECG de forma não-invasiva em ratos conscientes (n=6), sob contenção. Foram conduzidas análises de VFC nos domínios do tempo e da freqüência, tanto para a condição basal, como para as condições de bloqueio autonômico. Foram obtidos sinais de ECG de alta qualidade, viáveis para a análise de VFC. Conforme esperado, o intervalo RR médio foi significativamente reduzido na presença de atropina (p<0.05), e aumentado na presença de propranolol (p<0.001). Reforçando a validade do método, as potências espectrais de baixa e alta freqüência da VFC sofreram reduções significativas, respectivamente, na presença de propranolol (p<0.05) e atropina (p<0.05). Em resumo, o presente trabalho descreve um novo método, de baixo custo e natureza não-invasiva, para a realização do ECG de superfície em ratos conscientes.

Autonomic reactions to mutilation pictures: positive affect facilitates safety signal processing.

For survival, humans are continuously vigilant for signs of danger. Equally important, but less studied, is our ability to detect and respond to safety cues. The trait of positive affect may be a key component determining human variability in safety detection. Here we investigate autonomic and self-report reactivity to pictures of mutilated bodies, after reading a text about the art of mimicking injuries in the movies. Participants that scored high in positive affect trait showed attenuated autonomic reactions to the mutilation pictures. Thus, high positive affect facilitated engagement in safety cues and modulated reflexive reactions of the brain's defense system.

Cardiac autonomic dysfunction in rats chronically treated with anabolic steroid.

To date no published data exist regarding the effects of chronic high-dose anabolic-androgenic steroid administration on tonic cardiac autonomic control. The aim of this study was to evaluate, by power spectral analysis of heart rate variability (HRV), the effects of chronic treatment with supraphysiological doses of nandrolone decanoate (DECA) on tonic cardiac autonomic regulation in sedentary rats. Male Wistar rats were treated weekly with 10 mg kg(-1) of DECA (n=7) or vehicle (CONTROL, n=7) for 10 weeks. At the 8th week of treatment, electrocardiogram was recorded in the conscious state, for time- and frequency-domain HRV analysis. Parasympathetic indexes were reduced in DECA group: high-frequency power (CONTROL=11.1+/-3.0 ms2 vs. DECA=3.8+/-0.6 ms2, P<0.05), RMSSD (CONTROL=5.9+/-0.9 ms vs. DECA 3.5+/-0.3 ms; P<0.05) and pNN5 (CONTROL=31.5+/-7.5 ms vs. DECA=13.2+/-2.6 ms; P<0.05). The sympathetic index LF/HF tended to be higher in DECA group (CONTROL=0.65+/-0.15 vs. DECA=1.17+/-0.26, P=0.0546). In conclusion, chronic treatment with DECA, in rats, impairs tonic cardiac autonomic regulation, which may provide a key mechanism for anabolic steroid-induced arrhythmia and sudden cardiac death.