Untitled

Abstract

1. When the individual is alerted by painful or salient stimuli, there is a vigorous sympathetically mediated constriction of the cutaneous vascular bed. We investigated central pathways mediating this response using chronically implanted Doppler ultrasonic probes to measure cutaneous blood flow in the rabbit ear pinna and in the rat tail. 2. Blockade of neuronal function in the amygdala prevents cutaneous vasoconstriction elicited by salient stimuli, but does not prevent the response to painful stimuli. Blockade of neuronal function in raphe magnus/pallidus and the parapyramidal region in anesthetized rabbits prevents cutaneous vasoconstriction elicited by painful stimuli. A similar region of the medullary raphe regulates tail artery vasoconstriction in rats. Inhibition of neuronal function in this region reverses cutaneous vasoconstriction induced by cooling the animal. 3. Bulbospinal presympathetic neurons in the rostral medullary raphe region appear to regulate cutaneous blood flow responses occurring as part of the response to painful or dangerous environmental events and as part of the regulation of body temperature.

Dorsal and Ventral Hippocampus Modulate Autonomic Responses but Not Behavioral Consequences Associated to Acute Restraint Stress in Rats

“…Aversive situations cause a reduction in the tail blood flow in rats [44,87]. The fall of the tail blood flow would occur to prevent blood loss due to injuries, by keeping low amounts of blood in the skin, and another function would be the redistribution of blood to more important organs during a stress situation.…”

“…The fall of the tail blood flow would occur to prevent blood loss due to injuries, by keeping low amounts of blood in the skin, and another function would be the redistribution of blood to more important organs during a stress situation. The cutaneous tail temperature can be used as an indirect measurement of blood flow redistribution by the sympathetic nervous system in the rat [44,45,87]. Since that RS caused a fall in the tail temperature in control rats and pretreatment of the both DH and VH with CoCl 2 inhibited the fall in tail temperature caused by the restraint, our results suggest that the hippocampus is an important modulator of the sympathetic tonus in the tail artery during the exposure to an aversive situation.…”

Respiratory Component of the Orienting Reflex: A Novel Sensitive Index of Sensory-Induced Arousal in Rats

“…Sympathetic pathways that trigger tachycardia and cutaneous vasoconstriction are relatively slow in terms of both axonal propagation and post-synaptic effects. In addition, as cutaneous vasomotion is actively involved in thermoregulation in rats (Blessing, 2003; Ootsuka et al, 2008), it is possible that stimulus-induced cutaneous vasoconstriction may sometimes interfere with thermoregulatory vasodilation, resulting in relatively smaller or no responses to mild stimuli when heat dissipation is the priority. In contrast, respiratory responses are rapid as they are executed by striatal muscles innervated by rapidly conducting axons of spinal motoneurons.…”

Challenges of measuring body temperatures of free-ranging birds and mammals

“…Therefore, the time from capture to measurement should be as rapid as possible, particularly for small animals. For example, measurement of rectal temperature in mice typically results in an increase of 0.5-1.5 °C in 10-15 min [23] and is associated with peripheral cooling at the surface through vasoconstriction [30]. Thermometry is, therefore, inappropriate for studying functional body temperature responses or longitudinal patterns in body temperature regulation in free-ranging or free-moving animals.…”