RESUMO
The study of the neural basis of predatory behavior has been largely neglected over the recent years. Using an ethologically based approach, we presently delineate the prosencephalic systems mobilized during predation by examining Fos immunoreactivity in rats performing insect hunting. These results were further compared with those obtained from animals killed after the early nocturnal surge of food ingestion. First, predatory behavior was associated with a distinct Fos up-regulation in the ventrolateral caudoputamen at intermediate rostro-caudal levels, suggesting a possible candidate to organize the stereotyped sequence of actions seen during insect hunting. Insect predation also presented conspicuous mobilization of a neural network formed by a distinct amygdalar circuit (i.e. the postpiriform-transition area, the anterior part of cortical nucleus, anterior part of basomedial nucleus, posterior part of basolateral nucleus, and medial part of central nucleus) and affiliated sites in the bed nuclei of the stria terminalis (i.e. the rhomboid nucleus) and in the hypothalamus (i.e. the parasubthalamic nucleus). Accordingly, this network is likely to encode prey-related motivational values, such as prey's odor and taste, and to influence autonomic and motor control accompanying predatory eating. Notably, regular food intake was also associated with a relatively weak Fos up-regulation in this network. However, during regular surge of food intake, we observed a much larger mobilization in hypothalamic sites related to the homeostatic control of eating, namely, the arcuate nucleus and autonomic parts of the paraventricular nucleus. Overall, the present findings suggest potential neural systems involved in integrating prey-related motivational values and in organizing the stereotyped sequences of action seen during predation. Moreover, the comparison with regular food intake contrasts putative neural mechanisms controlling predatory related eating vs. regular food intake.
Assuntos
Comportamento Alimentar/fisiologia , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Comportamento Predatório/fisiologia , Prosencéfalo/fisiologia , Tonsila do Cerebelo/anatomia & histologia , Tonsila do Cerebelo/fisiologia , Animais , Mapeamento Encefálico , Ingestão de Alimentos/fisiologia , Hipotálamo/anatomia & histologia , Hipotálamo/fisiologia , Imuno-Histoquímica , Masculino , Modelos Neurológicos , Neostriado/anatomia & histologia , Neostriado/fisiologia , Rede Nervosa/anatomia & histologia , Vias Neurais/anatomia & histologia , Prosencéfalo/anatomia & histologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Núcleos Septais/anatomia & histologia , Núcleos Septais/fisiologia , Regulação para Cima/fisiologiaRESUMO
To investigate the role of type II 5'-deiodinase (5'D-II) in the expression of mitochondrial uncoupling protein (UCP) in brown adipose tissue (BAT), we injected intact male rats with reverse (r) 3,5,3'-triiodothyronine (T3; 100 micrograms. 100 g body wt-1. day-1), an inhibitor of 5'D-II, for 2-5 days. UCP decreased by approximately 20% in rats kept at 28 degreesC and failed to increase during cold exposure (4 degreesC). Next, thyroxine treatment (1-10 micrograms. 100 g body wt-1. day-1) increased nuclear T3 in rats kept at 28 or 4 degreesC. In these rats, nuclear T3 correlated positively with UCP. In addition, T3 (1-50 micrograms. 100 g body wt-1. day-1) given to intact rats (5-15 days; 28 degreesC) induced an approximately twofold increase in UCP. In these T3-treated animals, the interscapular BAT thermal response to norepinephrine infusion also correlated positively with T3 dose and UCP content. Treatment with propranolol or reserpine failed to block the T3 induction of UCP (approximately 1.8- and approximately 2.3-fold). The results emphasize the importance of local 5'D-II and reveal an independent role of T3 in the expression of UCP.
Assuntos
Tecido Adiposo Marrom/efeitos dos fármacos , Tecido Adiposo Marrom/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Membrana/metabolismo , Sistema Nervoso Simpático/fisiologia , Tri-Iodotironina/farmacologia , Tecido Adiposo Marrom/inervação , Tecido Adiposo Marrom/fisiologia , Antagonistas Adrenérgicos/farmacologia , Animais , Regulação da Temperatura Corporal/efeitos dos fármacos , Regulação da Temperatura Corporal/fisiologia , Núcleo Celular/metabolismo , Temperatura Baixa , Inibidores Enzimáticos/farmacologia , Iodeto Peroxidase/antagonistas & inibidores , Canais Iônicos , Isoenzimas/antagonistas & inibidores , Masculino , Proteínas Mitocondriais , Norepinefrina/farmacologia , Ratos , Ratos Wistar , Receptores dos Hormônios Tireóideos/metabolismo , Tiroxina/farmacologia , Tri-Iodotironina/metabolismo , Tri-Iodotironina Reversa/farmacologia , Proteína Desacopladora 1RESUMO
OBJECTIVE: To study the interference of mechanical vibration of the palm of the hand on the median nerve short-latency SEP components. METHODS: Electrically-elicited short-latency median nerve SEP were obtained before and during mechanical vibration (120 Hz) of the palm in two groups of normal individuals (6 in group I and 9 in group II). The amplitude of the different components was compared between the two conditions through non-parametric statistical tests. RESULTS: A significant reduction in the amplitude of the N9, P13/14 and N20 components was detected, however no overall significant changes were detected for the N18 component. CONCLUSIONS: Vibration interference reduced all studied components except the N18, these findings are interpreted as supporting evidence for the proposed association between the N18 component and the inhibitory activities elicited in the dorsal column nuclei.
Assuntos
Potenciais Somatossensoriais Evocados , Nervo Mediano/fisiologia , Vibração , Adulto , Feminino , Mãos/inervação , Humanos , Masculino , Pessoa de Meia-Idade , Tempo de Reação/fisiologiaRESUMO
This work describes the results of two experimental procedures related to the short latency median nerve somatosensory evoked potentials. In the first one, it was possible to show that there is a different rate of increase in the amplitude of the different components related to different intensities of stimulation. In the second one, the simultaneous stimulation of the median and the ulnar nerves disclosed an occlusive interaction which was larger for the N18 than for the other components. These results may be a support to the hypothesis that the N18 component generator is related to the mechanism of presynaptic inhibition within the cuneiform nucleus.
Assuntos
Eletroencefalografia , Potenciais Somatossensoriais Evocados/fisiologia , Nervo Mediano/fisiologia , Tempo de Reação/fisiologia , Adulto , Vias Aferentes/fisiologia , Mapeamento Encefálico , Estimulação Elétrica , Feminino , Humanos , Masculino , Bulbo/fisiologia , Pessoa de Meia-Idade , Inibição Neural/fisiologia , Nervo Ulnar/fisiologiaRESUMO
The activities of malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G-6-PDH), two NADPH-generating lipogenic enzymes, were measured in brown adipose tissue (BAT) of rats undergoing various neurohormonal manipulations. Methimazole-induced hypothyroidism doubled the activity of these two enzymes but, surprisingly, triiodothyronine (T3) given to hypothyroid rats caused a time- and dose-dependent stimulation of up to three- to fourfold. Unilateral BAT denervation modestly reduced the activity of these enzymes (approximately 30%) and failed to prevent the stimulation induced by hypothyroidism, whereas growth hormone (GH) successfully blocked this effect of hypothyroidism. Insulin stimulated both enzymes regardless of the thyroid status but failed to abolish the inhibitory effect of GH. In intact rats, cold exposure caused a time-dependent increase in the activity of both ME and G-6-PDH, which reached 5.2- and 3-fold, respectively, after 96 h. This cold-induced stimulation was not observed in hypothyroid rats, but it was restored by physiological doses of thyroxine (800 ng.100 g body wt-1.24 h-1). Replacement with T3 (300 ng.100 g body wt-1.24 h-1), in contrast, did not have this effect. In hypothyroid rats with hemidenervation of BAT, norepinephrine (NE) modestly increased ME and G-6-PDH activities in the denervated side, with little or no effect in the intact side. Receptor-saturating doses of T3 (50 micrograms.100 g body wt-1.day-1 over 48 h) stimulated two- and threefold both enzymes in both sides, reducing or obliterating the effect of denervation. The data suggest a complex neurohormonal regulation of the activity of ME and G-6-PDH in BAT.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Tecido Adiposo Marrom/enzimologia , Glucosefosfato Desidrogenase/metabolismo , Malato Desidrogenase/metabolismo , Tiroxina/fisiologia , Tri-Iodotironina/fisiologia , Tecido Adiposo Marrom/inervação , Animais , Temperatura Baixa , Denervação , Relação Dose-Resposta a Droga , Hipotireoidismo/enzimologia , Lipídeos/biossíntese , Masculino , NADP/metabolismo , Ratos , Ratos Sprague-Dawley , SimpatectomiaRESUMO
Electrocorticographic activity was automatically recorded in albino rats for 72 consecutive h and analyzed by procedures suitable to detect 24-h rhythms. Beta (alert wakefulness), theta (somnolence), delta (slow wave sleep) and sigma 1 (superficial synchronized sleep) activities showed a robust circadian rhythmic distribution. The acrophases (maxima of the adjusted cosine curve) occurred at 23:39, 07:59, 08:37 and 13:25 h, respectively. EMG atonia and extreme hypotonia (less than 10% of mean EMG level) episodes showed a 24-h rhythm peaking at 14:18 h. The temporal sequence within the circadian rest period, i.e., somnolence, slow, wave sleep, superficial synchronized sleep and paradoxical sleep, is very similar to that known to occur during the nocturnal sleep of humans
Assuntos
Ratos , Animais , Humanos , Masculino , Córtex Cerebral/fisiologia , Ritmo Circadiano , Eletroencefalografia , Sono/fisiologia , Nível de Alerta/fisiologia , Monitorização Fisiológica , Fases do Sono , Lobo Temporal/fisiologiaRESUMO
Electrocorticographic activity was automatically recorded in albino rats for 72 consecutive h and analyzed by procedures suitable to detect 24-h rhythms. Beta (alert wakefulness), theta (somnolence), delta (slow wave sleep) and sigma 1 (superficial synchronized sleep) activities showed a robust circadian rhythmic distribution. The acrophases (maxima of the adjusted cosine curve) occurred at 23:39, 07:59, 08:37 and 13:25 h, respectively. EMG atonia and extreme hypotonia (less than 10% of mean EMG level) episodes showed a 24-h rhythm peaking at 14:18 h. The temporal sequence within the circadian rest period, i.e., somnolence, slow wave sleep, superficial synchronized sleep and paradoxical sleep, is very similar to that known to occur during the nocturnal sleep of humans.
Assuntos
Córtex Cerebral/fisiologia , Ritmo Circadiano , Eletroencefalografia , Sono/fisiologia , Animais , Nível de Alerta/fisiologia , Humanos , Masculino , Monitorização Fisiológica , Ratos , Fases do Sono , Especificidade da Espécie , Lobo Temporal/fisiologiaRESUMO
An event recorder for use in ethological studies which is of simple and inexpensive construction is described. The apparatus consists essentially of a constant speed paper transport device and an ethogram sheet holder. Up to 20 different behavioral items may be recorded continuously in an accurate time sequence. The items are coded as hand-drawn pencil lines of different length perpendicular to the direction of the paper movement. Since the ethogram code sheets are exchangeable, an unlimited number of different ethograms may be used.