The Effects of Resistance Exercise on the Cardiorespiratory Tissue of Rats with Parkinson's Disease.

Parkinson's Disease (PD) affects the cardiorespiratory system, causing an increase in the left ventricular mass in the heart and respiratory muscle weakness in relation to healthy individuals. The objective of this study was to investigate the effects of progressive resistive physical exercise on the vertical ladder on the histomorphometry of cardiac tissue and respiratory muscles in rats with PD. Seventy male Wistar rats, aged 40 days old, were divided into Parkinson's (PD) and Sham (SH) groups; they were also subdivided into groups that performed progressive resistive physical exercise on the vertical ladder Before Surgery (ExBS), After Surgery (ExAS), and Before and After Surgery (ExBAS). The physical training was carried out before and/or after PD induction. Exercise was performed five times a week for 25 min/day for four or eight weeks. PD induction was conducted via electrolytic stimulation of the Substantia nigra of the animals' brains, adopting the following stereotaxic table coordinates: -4.9; lateral medium equal to 1.7, and dorsoventral equal to 8.1. For the morphometric analysis of the heart, the following variables were calculated: relative weight and diameter and thickness of the left ventricle. The diaphragm and the myocardial, intercostal, and abdominal muscles were stained with Hematoxylin and Eosin (HE). The histomorphometric analysis was performed using the ImageJ software to assess the cross-sectional area of muscles and the number of muscle fibers. Progressive resistance exercise promoted the hypertrophy of respiratory muscles and the left ventricle in animals with PD.

Behavioral characterization of the alarm reaction and anxiolytic-like effect of acute treatment with fluoxetine in piauçu fish.

In Ostariophysan fish, the detection of the alarm substance liberated into the water as a consequence of an attack by a predator elicits an alarm reaction or anti-predatory behavior. In this study, experiments were performed to: (i) describe and quantitatively characterize the behavioral and ventilatory responses in piauçu fish (Leporinus macrocephalus), individually and as part of a school, to conspecific alarm substance (CAS) and; (ii) test the effect of acute fluoxetine treatment on alarm reaction. Histological analysis revealed the presence of club cells in the intermediate and superficial layers of the epidermis. The predominant behavioral response to CAS was freezing for fish held individually, characterized by the cessation of the swimming activity as the animal settles to a bottom corner of the aquarium. Fish exposed to CAS showed decrease in the mean ventilatory frequency (approximately 13%) relative to control. In schools, CAS elicited a biphasic response that was characterized by erratic movements followed by increased school cohesion and immobility, reflected as an increased school cohesion (65.5% vs. -5.8% for controls) and in the number of animals near the bottom of the aquarium (42.0% vs. 6.5% for controls). Animals treated with single i.p. injections of fluoxetine (10 µg/g b.w.) did not exhibit alarm behavior following CAS stimulation. These results show that an alarm pheromone system is present in piauçu fish, evidenced by the presence of epidermal club cells and an alarm reaction induced by CAS and consequently of a chemosensory system to transmit the appropriate information to neural structures responsible for initiating anti-predator behavioral responses. In addition, fluoxetine treatment caused an anxiolytic-like effect following CAS exposure. Thus, the alarm reaction in piauçu can be a useful model for neuroethological and pharmacological studies of anxiety-related states.

Stressful and behavioral conditions that affect reversible cardiac arrest in the Nile tilapia, Oreochromis niloticus (Teleostei).

The objective of the present investigation was to study the reversible cardiac arrest (RCA) to visual stimuli in the unrestrained Nile tilapia (Oreochromis niloticus) as well as the modulation of this response and its behavioral component (arousal/orientation or startle response) by external and internal factors that interfere with alertness and emotionality. The study was preceded by the determination of the autonomic receptors that contribute to the establishment of the heart rate (HR) and the RCA. Systemic injection of atropine and propranolol showed that a double cardiac autonomic control is present in the tilapia. Basal HR was 79.8+/-1.8 beats min(-1) and HR assessed after double autonomic blockade was 74.1+/-3.3 beats min(-1). The mean interbeat interval was 0.79+/-0.40 s during baseline recording and the magnitude of RCA induced by a moving shadow (2.67+/-0.22 s) was higher than that induced by light (1.53+/-1.11 s). RCA is peripherally mediated by muscarinic receptors for it is abolished by atropine but not by propranolol. Stressful conditions like handling the animal outside the water or a nociceptive stimulus (subcutaneous 2% or 3% formalin injection) reduced the cardiac interbeat interval. A subanesthetic dose of barbiturate (5 mg kg(-1)) inhibited RCA induced by a moving shadow stimulus and the startle response, suggesting that an ideal degree of vigilance is necessary for its occurrence. Benzodiazepine injections (1.0 and 2.0 mg kg(-1)) abolished the reduction in magnitude of RCA induced by handling stress and facilitated the startle response, seen in the dry-cold season, in a dose-dependent manner. These data suggest that drugs that act on alertness and on emotionality modulate the magnitude of cardiac interbeat intervals and the corresponding behavioral response.