Conditional catecholamine changes in rhesus monkeys.
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Animals↗
Biomedical subjects
R McCarty
Publications and source records attributed to R McCarty.
Gender differences in sympathoadrenal activity in rats at rest and in response to footshock stress.
A comparison was made of the dynamics of sympathoadrenal activity in 11 age-matched male and female rats, under basal conditions and after exposure to footshock. Rats were prepared with indwelling catheters in the tail artery 24 h before the experiment. Measurements were made of plasma corticosterone (COR), norepinephrine (NE), epinephrine (EPI), dihydroxyphenylalanine (DOPA), dihydroxyphenylglycol (DHPG) and dihydroxyphenylacetic acid (DOPAC) under resting conditions, after transfer to the shock box (novelty) and at various times after footshock. Under basal conditions, males have significantly higher blood pressure and plasma DHPG/NE ratios but lower plasma levels of COR, NE and DOPAC than females. Three min after exposure to the shock chamber (novelty stress) there were significant increases in COR, EPI, NE and DHPG in both sexes, while DOPA increased only in females and DOPAC remained unchanged in both sexes. Footshock produced a further increase in EPI, NE and DOPAC within 2 min, which lasted about 15 min. There were significant sex differences in the extent and duration of the response of COR, EPI and DHPG. The data show that the female sympathoadrenal system is more reactive than that of the male to the stresses of a novel environment and footshock. The smaller DHPG/NE ratios in females at rest and after stress suggest that neuronal uptake of NE is lower in females than in males. The finding that stress produces larger increments of plasma DOPA and DOPAC in female rats indicates that tyrosine hydroxylase in the sympathetic nerve terminals and adrenal medulla may also be higher than in males.
Adrenal Glands↗
Catecholamines, stress, and disease: a psychobiological perspective.
OBJECTIVE: Research on the relationship between physiological responses to stressful stimulation and the onset of psychosomatic illnesses has been an area of intense interest for many years. Studies using animal models have contributed significantly to this field of inquiry by taking several complementary approaches. METHOD: Three specific research strategies taken in our laboratory will be highlighted here. Each involves studies in conscious, freely behaving animals. RESULTS: Genetically selected animals have been exposed to acute stressors to unmask neuroendocrine and autonomic abnormalities related to disease susceptibility. In addition, studies of aged animals suggest that exaggerated physiological responses to acute stress may underlie some age-related pathologies. Finally, a series of studies has revealed that exposure of laboratory animals to stressful stimulation may exert long-lasting influences on the ways in which these subjects respond in the future to the same or novel stressors. CONCLUSIONS: These findings illustrate how studies with laboratory animals have the potential for refining the questions that are posed in research with clinical populations and for providing insight into the underlying physiological mechanisms of individual variability in disease susceptibility and the development of appropriate therapeutic interventions.
Aging↗
Relationship between plasma norepinephrine and sympathetic neural activity.
For circulating norepinephrine (NE) to reflect sympathetic activity validly, plasma NE should show an intensity-dependent increase during sympathetic stimulation and decrease during sympathetic inhibition, and circulating NE should correlate with more directly obtained measures of sympathetic activity. Review of published evidence indicates that NE in peripheral plasma satisfies these criteria. However, models used to explain the relationship between circulating NE and sympathetic activity must take into account processes intervening between the synaptic cleft and free NE in the circulation and, since sympathetic outflow is regionalized, the contributions of specific vascular beds to circulating NE. In this report a model is presented where removal processes for NE are viewed as acting in series to produce a gradient in NE concentrations from synapse to plasma, and where the relative contributions of specific vascular beds are calculated from the arteriovenous difference in plasma NE across those beds and the percentage of cardiac output distributed to them. In general, venous plasma NE provides a useful estimation of average sympathetic outflow.
Animals↗