An inherent acceleratory effect of insulin on small intestinal transit and its pharmacological characterization in normal mice

Table 1 Effect of insulin administration on small intestinal transit and blood glucose levels in normal mice

Treatment Insulin (U/kg sc)	% SIT1	Blood glucose (%)2
Vehicle	52.06 ± 1.48	103.73 ± 4.19
2 μ	70.77 ± 0.62a	99.47 ± 1.59
2 m	73.53 ± 0.63a	94.54 ± 4.62
2	80.10 ± 1.93a	42.09 ± 1.78a

Each value represents the mean ± SE (n = 6) sc: subcutaneous; SIT: small intestinal transit;

^aP < 0.01 vs vehicle treated group;

¹Values are % SIT considering the total length of the intestine as 100, SIT was determined 40 min after insulin administration;

²Blood glucose was estimated 2 min before insulin/vehicle administration and 2 min before sacrificing the animals for the measurement of small intestinal transit (SIT), final blood glucose expressed as % considering the initial blood glucose of each animal as 100.

Table 2 Influence of various systems / mechanisms on insulin-induced acceleration of small intestinal transit in normal mice

PretreatmentAgent/vehicle(mg/kg iv)1	TreatmentInsulin(2 µU/kg sc)2	% SITmean ± SE	%Acceleration	%Inhibition
Vehicle	Vehicle	55.10 ± 1.46	--	--
Vehicle	Insulin	74.76 ± 1.40a	35.683	--
Atropine (1)	Vehicle	29.19 ± 3.28a	--	47.023
Atropine (1)	Insulin	37.32 ± 3.58b	--	50.084
Clonidine (0.1)	Vehicle	15.50 ± 1.46a	--	71.863
Clonidine (0.1)	Insulin	27.71 ± 4.78b	--	62.934
Ondansetron (1)	Vehicle	51.69 ± 1.13	--	6.183
Ondansetron (1)	Insulin	63.84 ± 5.88	--	14.604
Naloxone (5)	Vehicle	32.39 ± 2.56a	--	41.213
Naloxone (5)	Insulin	53.90 ± 2.95b	--	27.904
Verapamil (8)	Vehicle	40.72 ± 1.72a	--	26.093
Verapamil (8)	Insulin	48.61 ± 3.27b	--	34.974
Glibenclamide(10)	Vehicle	79.23 ± 1.52a	43.793	--
Glibenclamide(10)	Insulin	88.88 ± 3.52	18.884	--
Glibenclamide(10)	Insulin	88.88 ± 3.52	61.303	--

Each value represents the mean ± SE (n = 6) or %. ^aP < 0.01 vs vehicle + vehicle group. ^bP < 0.01 vs vehicle + insulin group. ¹Agent/vehicle administered 50 min before SIT measurement. ²Insulin/vehicle administered 40 min before SIT measurement. ³compared with vehicle + vehicle group. ⁴compared with vehicle + insulin group.