Infralimbic cortex controls core body temperature in a histamine dependent manner.
An increase in body temperature accelerates biochemical reactions and behavioral and physiological responses. A mechanism to actively increase body temperature would be beneficial during motivated behaviors. The prefrontal cortex is implicated in organizing motivated behavior; the infralimbic cortex, a subregion of the medial prefrontal cortex, has the necessary connectivity to serve the role of initiating such thermogenic mechanism at the beginning of the appetitive phase of motivated behavior; further, this cortex is active during motivated behavior and its disinhibition produces a marked behavioral and vegetative arousal increase, together with increases in histamine levels. We wanted to explore if this arousal was related to histaminergic activation after pharmacological infralimbic disinhibition and during the appetitive phase of motivated behavior. We measured core temperature and motor activity in response to picrotoxin injection in the infralimbic cortex, as well as during food-related appetitive behavior, evoked by enticing hungry rats with food. Pretreatment with the H1 receptor antagonist pyrilamine decreased thermal response to picrotoxin and enticement and completely blunted motor response to enticement. Motor and temperature responses to enticement were also completely abolished by infralimbic cortex inhibition with muscimol. To assess if this histamine dependent temperature increase was produced by an active sympathetic mediated thermogenic mechanism or was just a consequence of increased locomotor activity, we injected propranolol (i.p.), a β adrenergic receptor blocker, before picrotoxin injection into the infralimbic cortex. Propranolol reduced the temperature increase without affecting locomotor activity. Altogether, these results suggest that infralimbic activation is necessary for appetitive behavior by inducing a motor and a vegetative arousal increase mediated by central histamine.
Departamento de Fisiologia, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Chile. Electronic address: meriverouccl@gmail.com.
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Riveros
Departamento de Fisiologia, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Chile. Electronic address: guayec@gmail.com.
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Perdomo
Departamento de Fisiologia, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Chile. Electronic address: ftorrealba@bio.puc.cl.
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Torrealba
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D005625:Frontal Lobe / Q000187:drug effects / Q000502:physiology*; D006632:Histamine / Q000502:physiology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D010852:Picrotoxin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000319:Adrenergic beta-Antagonists; D006632:Histamine; D006634:Histamine H1 Antagonists; D010852:Picrotoxin; D011433:Propranolol; D011738:Pyrilamine
Body temperature; H1 receptors; Histamine; Infralimbic cortex