Physiology & behavior
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Physiology & behavior · Aug 2011
Sex differences in physiological and affective responses to stress in remitted depression.
Major depressive disorder (MDD) is associated with alterations in stress physiology. Severe melancholic depression is characterized by hypercortisolism, but community dwelling mildly depressed individuals and those with remitted MDD have shown reduced or normal reactivity to stress. There are also pronounced sex differences both in the incidence of MDD and in stress reactivity. ⋯ Women from both groups reported greater post-stress negative affect than men. In contrast, men from both groups reported higher positive affect before and after stress than women. Given that the sex difference findings were not dependent on depression history, self-reported affective differences in response to stress may predate depressive symptoms and contribute to sex differences in depression incidence.
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Physiology & behavior · Aug 2011
Effects of dominance status on conditioned defeat and expression of 5-HT1A and 5-HT2A receptors.
Past experience can alter how individuals respond to stressful events. The brain serotonin system is a key factor modulating stress-related behavior and may contribute to individual variation in coping styles. In this study we investigated whether dominant and subordinate hamsters respond differently to social defeat and whether their behavioral responses are associated with changes in 5-HT1A and 5-HT2A receptor immunoreactivity in several limbic brain regions. ⋯ Subordinates also had more 5-HT1A immunopositive cells in the dorsal medial amygdala than did controls. Finally, dominants had fewer 5-HT1A immunopositive cells in the paraventricular nucleus of the hypothalamus compared to controls. Our results indicate that dominant social status results in a blunted conditioned defeat response and a distinct pattern of 5-HT1A receptor expression, which may contribute to resistance to conditioned defeat.
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Physiology & behavior · May 2011
Identification of low and high frequency ranges for heart rate variability and blood pressure variability analyses using pharmacological autonomic blockade with atropine and propranolol in swine.
Understanding autonomic nervous system functioning, which mediates behavioral and physiological responses to stress, offers great potential for assessing farm animal stress and welfare. Evaluation of heart rate variability (HRV) and blood pressure variability (BPV), using time and frequency domain analyses may provide a sensitive and reliable measure of affective states and stress-mediated changes in sympathetic and parasympathetic tones. The aim of this research was to define low (LF) and high frequency (HF) power spectral ranges using pharmacological autonomic blockade, and to examine HRV and BPV parameter changes in response to atropine and propranolol in swine. ⋯ Atropine led to a dominant sympathovagal balance of the cardiac activity in pigs. In addition, atropine led to an increase in LF power of both systolic and diastolic blood pressures in gilts suggesting vagal tone mediation of BPV. The understanding of autonomic regulation of HRV and BPV in domestic swine facilitates our ability to detect and quantify stress responses, and broadens its application in assessing farm animal welfare.
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Physiology & behavior · Feb 2011
Randomized Controlled Trial Clinical TrialIntensive exercise: a remedy for childhood obesity?
Acute exercise can affect the energy intake regulation, which is of major interest in terms of obesity intervention and weight loss. ⋯ Intensive exercise favors a negative energy balance by dually affecting energy expenditure and energy intake without changes in appetite sensations, suggesting that adolescents are not at risk of food frustration.
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Physiology & behavior · Dec 2010
Treadmill exercise inhibits traumatic brain injury-induced hippocampal apoptosis.
Traumatic brain injury (TBI) occurs when an outside force impacts the brain. The main problem associated with TBI is neuronal cell death of the brain, and the outcome of TBI ranges from complete recovery to permanent disability, and sometimes death. Physical exercise is known to ameliorate neurologic impairment induced by various brain insults. ⋯ Treadmill exercise alleviated short-term memory impairment, and decreased DNA fragmentation and caspase-3 expression in the hippocampus. In addition, treadmill exercise remarkably suppressed expression of Bax protein and slightly increased expression of Bcl-2 protein in TBI-induced rats. The present study showed that treadmill exercise might overcome TBI-induced apoptotic neuronal cell death, thus facilitating recovery following TBI.