Physiology & behavior
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Physiology & behavior · Jan 2010
Ontogenetic role of angiontensin-converting enzyme in rats: thirst and sodium appetite evaluation.
We investigated the influence of captopril (an angiotensin converting enzyme inhibitor) treatment during pregnancy and lactation period on hydromineral balance of the male adult offspring, particularly, concerning thirst and sodium appetite. We did not observe significant alterations in basal hydromineral (water intake, 0.3M NaCl intake, volume and sodium urinary concentration) or cardiovascular parameters in adult male rats perinatally treated with captopril compared to controls. However, male offspring rats that perinatally exposed to captopril showed a significant attenuation in water intake induced by osmotic stimulation, extracellular dehydration and beta-adrenergic stimulation. ⋯ This treatment also attenuated thirst and sodium appetite aroused during inhibition of peripheral angiotensin II generation raised by low concentration of captopril in the adult offspring. Interestingly, perinatal exposure to captopril did not alter water or salt intake induced by i.c.v. administration of angiotensin I or angiotensin II. These results showed that chronic inhibition of angiotensin converting enzyme during pregnancy and lactation modifies the regulation of induced thirst and sodium appetite in adulthood.
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Physiology & behavior · Dec 2009
Psychophysical correlates in children with sensory modulation disorder (SMD).
Sensory modulation disorder (SMD), affecting approximately 5% of children, is characterized by sensory over or under-responsiveness to a range of stimuli in several modalities. Children with over-responsiveness (SOR) demonstrate increased aversion to certain natural stimuli that manifests as increased distress and avoidance behaviors to common stimuli, accompanied by abnormal electrodermal responses and brain evoked potentials to various stimuli. This study is the first to use quantitative sensory testing to characterize the somatosensory sub-modalities of children with SMD. ⋯ No significant differences between groups were found in most of the sensory and pain thresholds at any tested site. These results indicate, for the first time, that children with SMD perceive more pain, and that their pain lasts longer. Our results demonstrate that SOR does not imply lowered sensory thresholds but abnormal processing suprathreshold noxious stimuli.
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Physiology & behavior · Sep 2009
Naltrexone fails to increase pain affect in response to inflammatory pain in a novel escape/avoidance paradigm.
The non-specific opioid antagonist naltrexone has traditionally been used as treatment for opioid overdose, as well as in research settings as an antagonist to examine opioid and non-opioid mediated analgesia. However, the mechanisms by which this drug operates are not well understood, and its exact effects on sensory and affective pain processes remain uncertain. Various studies have demonstrated that naltrexone behaves in a paradoxical manner, leading to analgesia, no discernable changes, or an increase in pain, depending on the circumstances of the study. ⋯ Eighty-eight male Sprague-Dawley rats were used to test these hypotheses by measuring Mechanical Paw Withdrawal Thresholds before and after naltrexone injection and by assessing performance in the Place Escape Avoidance Paradigm test, a novel paradigm to test pain affect, in which naltrexone had not been utilized. The results demonstrated that naltrexone failed to increase place/escape avoidance behavior as anticipated, but rather produced a slight, but non-significant, decrease in escape avoidance behavior. Further research is needed to elucidate the differential effects of naltrexone on various aspects of pain-related behavior.
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Physiology & behavior · Aug 2009
Nocifensive behaviors components evoked by brief laser pulses are mediated by C fibers.
Nocifensive behavior involves several response elements that have been used to assess neuropharmacological effects in different animal models of pain. Our previous analysis of laser-evoked nocifensive behaviors suggested that hierarchically organized responses in the nocifensive motor system are recruited in varying degrees by noxious stimuli of different intensities. Nocifensive behaviors can be differentially elicited and mediated by different classes of nociceptors. ⋯ Applying the neurotoxin, capsaicin, which selectively inhibits C fibers, to the sciatic nerves of rats, differentially blocked nocifensive behavioral components of flinch, withdrawal and licking but not non-nocifensive responses, namely movement and head turning. Based on these results we suggest that flinch, withdrawal and licking are mediated by C fibers, which are temporally associated with the nocifensive motor system as well as spinal and cortical evoked potentials. These results link hierarchically organized nocifensive responses and the afferent C fibers in the nocifensive motor system.
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Physiology & behavior · Jun 2009
Behavioral effects of ventilated micro-environment housing in three inbred mouse strains.
Animal facilities aim to combine animal welfare with cost-efficiency and limited care staff requirements, and individually ventilated cage (IVC) systems were developed towards these goals. While IVC have great sanitary advantages both for the animals but also for the care staff, these systems involve potentially deleterious features such as high levels of air renewal, noise, and subtle vibrations of the racks because of the air filtering system used, but also reduce the frequency of stressful cage changes. It is unknown in how far these conditions may influence the animals' behavior. ⋯ Results demonstrate robust effects of IVC in multiple behavioral tests with the direction of the effect strongly dependent on strain and sex. These data should serve to alert researchers that a switch to IVC housing during the course of an experiment has the potential to bias results in a serious manner. In addition, behavioral baseline data will have to be re-established once the switch has been completed.