Inhibitory effect of neurotensin on proline

The effect of neurotensin (NT) on proline absorption across rat jejunum was investigated using the single-pass perfusion technique. This study showed that intravenous administration of NT produced a dose-dependent inhibition of proline absorption. Thus, NT at a 0.16 pmol/kg/min concentration gave 10% decrease in proline absorption while 0.32 and 1.6 pmol/kg/min concentration gave 31% and 45% decrease, respectively. In the absence of Na, proline absorption decreased to 77% from control values. No change in proline absorption was noticed when NT at a concentration of 0.32 pmol/kg/min was intravenously injected in the absence of sodium from the perfusion solution. Water absorption did not show significant changes (P > 0.05) in presence or absence of NT. Moreover, NT did not produce a significant change (P > 0.2) in intracellular proline accumulation. NT inhibited proline absorption through an indirect mechanism that is Na-dependent and independent of changes in water absorption.