title: Hypothalamic mechanisms coordinating cardiorespiratory function during exercise and defensive behaviour.
abstract: Defensive behaviour evoked by mild or moderate psychological stress as well as increased activity and arousal are part of everyday life in humans and other animals. Both defensive behaviour and exercise are associated with marked and often quite stereotyped changes in autonomic and respiratory function. These patterned responses are generated by feed-forward or "central command" mechanisms, and are also modulated by feedback from peripheral receptors. In this review we first describe the pattern of autonomic and respiratory changes associated with defensive behaviour and exercise, and then discuss the central mechanisms that generate these patterned responses in the light of recent studies, with a particular focus on the role of the dorsomedial hypothalamus (DMH). We consider the hypothesis that the cardiorespiratory changes associated with defensive behaviour and exercise may, at least in part, be driven by common central mechanisms. Finally, we discuss the possible role of the DMH in generating circadian rhythms in arterial blood pressure and heart rate, and also in generating longer-term increases in sympathetic activity in some types of hypertension.
authors: School of Medical Sciences (Physiology) and Bosch Institute, The University of Sydney, NSW 2006, Australia. rogerd@physiol.usyd.edu.au
authors: R A L
authors: RA
authors: Dampney
authors: J
authors: J
authors: Horiuchi
authors: L M
authors: LM
authors: McDowall
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena; D002940:Circadian Rhythm / Q000502:physiology; D004302:Dorsomedial Hypothalamic Nucleus / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D012143:Respiratory Physiological Phenomena; D013315:Stress, Psychological / Q000503:physiopathology*