Objective:

2

To investigate the effect of

Heliotropium indicum

L. (

H. indicum

L.) on uterine involution and its underlying mechanisms in both

in vivo

and

in vitro

study.

Methods:

2

For

in vivo

studies

postpartum rats were randomly divided into 2 groups (n=24 for each): control group and treated group which were orally and daily administered with ethanolic extract of

H. indicum

L. (250 mg/kg body weight) until day 5 of postpartum. Uteri were collected for analysis of weight

cross-sectional area

collagen cross-sectional area

and collagen content on postpartum day 1

3

and 5 (n=8 for each) from both groups. Blood samples were collected for hepatotoxicity and 17ß-estradiol (E

2

) measurement. For

in vitro

studies

the extract effects on uterine contraction at half maximum effective concentration of 2.50 mg/mL were studied in organ bath system for at least 20 min.

Results:

2

Uterine parameters were significantly decreased after treated with extract of

H. indicum

L. (

P

<

0.05).

H. indicum

L. extract significantly accelerated the reduction of those parameters and significantly decreased E

2

(

P

<

0.05). The extract facilitated uterine involution with no hepatotoxicity.

H. indicum

L. extract significantly stimulated uterine contraction (

P

<

0.05) and synergized with oxytocin

prostaglandin and its precursor

linoleic acid. By investigating the different sequencing of the extract with the additional stimulants (added before or after)

the two showed antagonistic effects

but still showed potentiated force when compared with control (without the stimulants).

Conclusions:

2

The underlying mechanisms by which

H. indicum

L. facilitated uterine involution might be due to reducing E

2

which induces collagenase activity

leading to decreases in uterine weight and size and stimulating uterine contraction. Our study provides new findings for future drug development for facilitating uterine involution with

H. indicum

L.