RESUMEN
In this study, we evaluated the expression of the Zenk protein within the nucleus taeniae of the pigeon’s amygdala (TnA) after training in a classical aversive conditioning, in order to improve our understanding of its functional role in birds. Thirty-two 18-month-old adult male pigeons (Columba livia), weighing on average 350 g, were trained under different conditions: with tone-shock associations (experimental group; EG); with shock-alone presentations (shock group; SG); with tone-alone presentations (tone group; TG); with exposure to the training chamber without stimulation (context group; CG), and with daily handling (naive group; NG). The number of immunoreactive nuclei was counted in the whole TnA region and is reported as density of Zenk-positive nuclei. This density of Zenk-positive cells in the TnA was significantly greater for the EG, SG and TG than for the CG and NG (P < 0.05). The data indicate an expression of Zenk in the TnA that was driven by experience, supporting the role of this brain area as a critical element for neural processing of aversive stimuli as well as meaningful novel stimuli.
Asunto(s)
Animales , Masculino , Amígdala del Cerebelo/metabolismo , Proteína 1 de la Respuesta de Crecimiento Precoz/metabolismo , Miedo/fisiología , Genes Inmediatos-Precoces/fisiología , Estimulación Acústica , Amígdala del Cerebelo/anatomía & histología , Recuento de Células , Columbidae , Condicionamiento Clásico/fisiología , Estimulación Eléctrica , Factores de TiempoRESUMEN
Venom of the South American rattlesnake, Crotalus durissus terrificus (Cdt), presents myotoxic and neurotoxic outcomes, but reports on its effects on the liver are scarce. This study examined the hepatotoxicity resulting from Cdt venom administration (100, 200 and 300 miug/kg) in male Wistar rats. Animais were studies at 3, 9 and 12 hours after venom injection. The hepatotoxicity was assessed through serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), gamma glutamyl transferase (GGT), bilirrubin and also by histopathological evaluation. All the different concentrations of Cdt venom resulted in increased levels of hepatic enzymes, when compared with the control group, except for the 100 miug/kg dose, which presented normal levels at 9 and 12 hours after venom administration. Bilirrubin levels remained unchanged by Cdt venom. Histological analysis revealed endothelial damage, inflammatory cell infiltration, as well as sinusoidal and portal congestion. Based on these observations, we may conclude that Cdt venom causes dose- and time-dependent hepatic damage in rats, characterized by elevated hepatic enzyme levels and histological alterations
Asunto(s)
Animales , Masculino , Hígado/anatomía & histología , Hígado , Venenos de Crotálidos/envenenamiento , Venenos de Crotálidos/toxicidad , Alanina Transaminasa/administración & dosificación , Aspartato Aminotransferasas/administración & dosificación , Fosfatasa Alcalina/administración & dosificación , Ratas WistarRESUMEN
We investigated the effects of hippocampal lesions with ibotenic acid (IBO) on the memory of the sound-context-shock association during reexposure to the conditioning context. Twenty-nine adult pigeons were assigned to a non-lesioned control group (CG, N = 7), a sham-lesioned group (SG, N = 7), a hippocampus-lesioned experimental group (EG, N = 7), and to an unpaired nonlesioned group (tone-alone exposure) (NG, N = 8). All pigeons were submitted to a 20-min session in the conditioning chamber with three associations of sound (1000 Hz, 85 dB, 1 s) and shock (10 mA, 1 s). Experimental and sham lesions were performed 24 h later (EG and SG) when EG birds received three bilateral injections (anteroposterior (A), 4.5, 5.25 and 7.0) of IBO (1 µl and 1 µg/µl) and SG received one bilateral injection (A, 5.25) of PBS. The animals were reexposed to the training context 5 days after the lesion. Behavior was videotaped for 20 min and analyzed at 30-s intervals. A significantly higher percent rating of immobility was observed for CG (median, 95.1; range, 79.2 to 100.0) and SG (median, 90.0; range, 69.6 to 95.0) compared to EG (median, 11.62; range, 3.83 to 50.1) and NG (median, 7.33; range, 6.2 to 28.1) (P<0.001) in the training context. These results suggest impairment of contextual fear in birds who received lesions one day after conditioning and a role for the hippocampus in the modulation of emotional aversive memories in pigeons
Asunto(s)
Animales , Condicionamiento Clásico/fisiología , Agonistas de Aminoácidos Excitadores/farmacología , Miedo/fisiología , Hipocampo/lesiones , Hipocampo/fisiología , Ácido Iboténico/farmacología , Aprendizaje/fisiología , Memoria/fisiología , Encéfalo/citología , Columbidae , Señales (Psicología) , Hipocampo/citología , Hipocampo/efectos de los fármacosRESUMEN
The effect of massive lesions of the telencephalon on the repertoire of captive pigeons were investigated. The behavior of four birds with an intact telencephalon was compared to that of four birds submitted to ablation of telencephalic structures. Behavioral audio recording was done according to previously defined categories in three daily sessions for fifteen days. Experimental birds were followed up for month. Immediately after the lesion, operated birds showed decreases in the occurrence of different behaviors such as coording movements, feeding, interaction, preening, maintenance, exploration and vocalization and increases in locomotion and discrete movements of the body when compared to the control birds (P<0.05). Recovery of exploration (P<0.05), feeding and localization was during the follow-up period. These data are interpreted as suggestive of a functional role of the telencephalon in the organization of behavior and a long-term recovery of behavior after detelencephalation
Asunto(s)
Animales , Conducta Animal/fisiología , Columbidae/fisiología , Telencéfalo/fisiología , Conducta Exploratoria/fisiología , Conducta Alimentaria/fisiología , Aseo Animal/fisiología , Locomoción/fisiología , Movimiento/fisiología , Plasticidad Neuronal/fisiología , Vocalización Animal/fisiologíaRESUMEN
Habituation to sound stimulation was analyzed in terms of the functional role of the telencephalon in learning. Sixteen pigeons were exposed to 1000-Hz, 83-dB, 1-s sound (stimulus A) at 30-s intervals until there was habituation of the exploratory and pre-exploratory responses. The learning criterion was 10 trials without the occurrence of these responses. Twenty-four hours after habituation to stimulus A the birds were tested with a 500-Hz, 85-dB, 1-s sound (stimulus B). On the day following habituation to stimulus B, the birds of the experimental group (N=8) suffered ablation of the telencephalon and the birds of the control group (N=8) had sham surgery. Retesting with the same sequence of procedures was carried out 10 days after surgery. in the POST-lesion situation there was a decrease of the number of habituation trials to stimulus A (P<0.01) and to stimulus B (P<0.05) by experimental pigeons compared to the PRE-lesion situation. The data suggest an interaction of a facilitatory effect of the lesion and long-term learning effects
Asunto(s)
Animales , Estimulación Acústica , Conducta Exploratoria/fisiología , Habituación Psicofisiológica/fisiología , Telencéfalo/fisiología , ColumbidaeRESUMEN
Operant discrimination learning was analyzed in pigeons after massive telencephalic lesions. Twenty-one pigeons were divided into the three groups: non-lesioned (N=6), sham-lesioned (N=5) and telencephalon lesioned (N=10). Lesion surgeries were carried out before any experimental training. Learning procedures were run in the same sequence for all groups and under a food deprivation of 80 percent of the ad libitum weight. Successive discrimination was programmed by the alternation of red and yellow lights in the right key of a standard operant chamber: the red key was correlated with extinction. Sessions were run until steady-state key peck rates were obtained. The following results demonstrate discrimination learning required a larger number of sessions for lesioned pigeons (P<0.05). They showed increased response rates in red (26.43 +/- 2.59) and yellow (11.17 +/- 2.86) components...