Document Detail


Evidence from catch-up growth and hoarding behavior of rats that exposure to hypobaric air lowers the body-mass set point.
MedLine Citation:
PMID:  16671587     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The depression of body growth rate and the reduction of body mass for chronological age and gender in growing experimental animals exposed to hypobaric air (simulated high altitude = SHA) have been associated with hypophagia because of reduced appetite. Catch-up growth during protein recovery after a short period of protein restriction only occurs if food intake becomes super-normal, which should not be possible under hypoxic conditions if the set-point for appetite is adjusted by the level of SHA. The present investigation was designed to test the hypothesis that growth retardation during exposure to SHA is due to an alteration of the neural mechanism for setting body mass size rather than a primary alteration of the central set-point for appetite. One group of female rats aged 35 d were exposed to SHA (5460m) in a SHA chamber for 27 d (HX rats). Other group was maintained under local barometric pressure conditions (NX rats). One half of both NX and HX rats were fed a protein-free diet for the initial 9 d of the experimental period. From this time on, they were fed a diet containing 20% protein, as were the remaining rats of both groups during the entire experimental period. The growth rates of both mass and length of the body were significantly depressed in well-nourished rats exposed to SHA during the entire observation period when compared to normoxic ones. At its end, body mass and body length were 24% and 21% less in HX than in NX rats. Growth rates were negatively affected by protein restriction in both NX and HX rats. During protein recovery, they reached supernormal values in response to supernormal levels of energy intake that allowed a complete catch-up of both body mass and length. The finding that energy intake during the period of protein rehabilitation in HX rats previously stunted by protein restriction was markedly higher than in HX control ones at equal levels of hypoxia demonstrates that the degree of hypoxia does not determine directly the degree of appetite and energy intake. Furthermore, the finding that catch-up growth in the stunted HX rats returns the animal only to the stunted size appropriate for the hypoxic animal supports the hypothesis that hypoxia lowers the set-point for body mass size, which is reached by inhibition of appetite. Confirmation of the hypothesis was done by assessment of the set-point of body mass by the behavioral method of the weight threshold to hoard food. It was lowered by 17.0% in HX rats.
Authors:
Carlos E Bozzini; Christian E Lezón; María F Norese; María I Conti; María P Martínez; María I Olivera; Rosa M Alippi
Related Documents :
970147 - The potassium concentration in cerebrospinal fluid in young and adult rats following co...
22323657 - Influence of housing conditions from weaning to adulthood on the ventilatory, thermoreg...
15261097 - Nitric oxide pathway in the nucleus raphe magnus modulates hypoxic ventilatory response...
3918867 - Respiratory and haemodynamic effects of lateral thoracotomy or sternotomy in mechanical...
1871157 - A comparison of plasma prolactin levels in young female long-evans and holtzman rats as...
15256707 - 3,5-nonadiyne isolated from the rhizome of cachrys ferulacea inhibits endogenous nitric...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Growth, development, and aging : GDA     Volume:  69     ISSN:  1041-1232     ISO Abbreviation:  Growth Dev Aging     Publication Date:  2005  
Date Detail:
Created Date:  2006-05-04     Completed Date:  2006-06-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8809704     Medline TA:  Growth Dev Aging     Country:  United States    
Other Details:
Languages:  eng     Pagination:  81-8     Citation Subset:  IM    
Affiliation:
Department of Physiology, Faculty of Odontology, University of Buenos Aires, Argentina. cebozi@fisio.odon.uba.ar
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Altitude
Animals
Anoxia / physiopathology*
Appetite Regulation / physiology
Atmospheric Pressure*
Body Size / physiology*
Diet, Protein-Restricted / adverse effects*
Feeding Behavior / physiology*
Female
Rats
Rats, Wistar

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Distribution of components of the insulin-like growth factor system in the temporomandibular joint o...
Next Document:  Catch-up in body weight of intrauterine growth retarded (IUGR) rats castrated and treated with growt...