Vol. 278, Issue 1, R44-R49, January 2000
Ontogeny of hypertonic preabsorptive inhibitory control of
intake in neonatal rats
Aron
Weller1,
Ludmila
Tsitolovskya1,
Iris H.
Gispan1, and
Gerard P.
Smith2
1 Developmental Psychobiology Laboratory,
Department of Psychology, Bar Ilan University, Ramat Gan 52900, Israel; and 2 Department of Psychiatry, Joan and
Sanford I. Weill Medical College of Cornell University and E. W. Bourne
Research Laboratory, New York-Presbyterian Hospital, Westchester
Division, White Plains, New York 10605
The ontogenetic
development of postingestive inhibitory control of ingestion by the
osmotic load of a preload was examined in rats. On postnatal days
6 (P6) and 12 (P12), pups were deprived for either 6 or 24 h. Gastric preloads (5% body wt) of water, mannitol (a sugar alcohol
that is not absorbed) in six concentrations [from 0.125 M
(hypotonic) to 1.0 M (hypertonic)], or sham preloads were
administered 5 min before a 30-min intake test. Compared with sham
treatment, isotonic mannitol (0.25 M), a probe of volumetric control,
significantly reduced intake on P12, but not on P6. Compared with
isotonic mannitol, the three highest hypertonic concentrations (0.5, 0.66, and 1.0 M) significantly decreased intake on P12, at both levels
of deprivation. On P6, 0.66 and 1.0 M mannitol reduced intake after 24 h, but not after 6 h, of deprivation. Thus, on P6, the hypertonic
control was detectable only after prolonged deprivation and the
volumetric control was not present. On P12, both controls were observed
and the hypertonic control was more potent than on P6.
mannitol; osmotic load; satiety; independent ingestion
