Lactase persistence versus decline in human adults: multifactorial events are involved in down-regulation after weaning.
Gastroenterology
; 112(5): 1506-14, 1997 May.
Article
en En
| MEDLINE
| ID: mdl-9136828
BACKGROUND & AIMS: In nonhuman mammals, lactase activity declines during or after weaning. In contrast, about one half of the human species maintains high lactase activity even in adulthood. To clarify this difference, this study examined some parameters for which contrasting observations have been reported in connection with lactase decline. METHODS: Lactase activity, lactase messenger RNA (mRNA) levels, and in vitro lactase biosynthesis were determined in normal jejunal samples from a large group of white adults, all born in or near Naples. RESULTS: Of 44 individuals, 10 were lactase persistent and 34 were hypolactasic. Biosynthesis of prolactase correlated well with lactase mRNA levels, indicating transcriptional control; it did less so with steady-state lactase activity. Examination of lactase mRNA levels and lactase activity/lactase mRNA ratios revealed a heterogeneous pattern of lactase mRNA level, lactase synthesis, and activity in both lactase persistent and hypolactasic subjects. CONCLUSIONS: Both transcriptional and posttranscriptional factors cause the decline of intestinal lactase. This probably explains the multifarious observations that most studies on adult-type hypolactasia have reported. The single overriding factor distinguishing lactase-persistent subjects from hypolactasic subjects is the high rate of lactase biosynthesis.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Beta-Galactosidasa
Límite:
Adult
/
Aged
/
Female
/
Humans
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Male
/
Middle aged
Idioma:
En
Revista:
Gastroenterology
Año:
1997
Tipo del documento:
Article
País de afiliación:
Italia
Pais de publicación:
Estados Unidos