Objective:

2

To explore the underlying mechanism of inhibition by Jingui Shenqi Pills (JGSQP) on glucocorticoid-enhanced axial length elongation in experimental lens-induced myopia (LIM) guinea pigs.

Methods:

2

Sixty 2-week old male guinea pigs were randomly divided into 4 groups with 15 guinea pigs in each group

according to the random numbers generated by SPSS software: control

LIM

saline and JGSQP groups. The control group includes animals with no treatment

while the guinea pigs in the other 3 groups received lens-induced myopization on the right eyes throughout the experiment (for 8 weeks). The saline and JGSQP groups were given daily intraperitoneal injections of 10 mg/kg hydrocortisone for 2 consecutive weeks at the same time

and then orally administered either saline or JGSQP [13.5 g/(kg • d) for 6 consecutive weeks. Body weight

anal temperature and animal appearance were observed and recorded to evaluate the GC-associated symptoms. The ocular parameters

including refraction and axial length

were measured by streak retinoscopy and A-scan ultrasonography

respectively. The levels of plasma hormones associated with the hypothalamic-pituitary-adrenal axis (HPAA)

including free triiodothyronine

free thyroxine

estradiol and testosterone

were measured by radioimmunoassay

and cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate were measured by enzyme-linked immunosorbent assay. In addition

the mRNA and protein expressions of retinal amphiregulin (AREG) was measured by quantitative real-time polymerase chain reaction and Western blotting

respectively.

Results:

2

JGSQP effectively increased body weight and anal temperature

improved animal appearance and suppressed axial length elongation in glucocorticoid- enhanced myopic guinea pigs with normalization of 4 HPAA-associated plasma hormones (all

P

<

0.05). The plasma level of cAMP was significantly increased

whereas the plasma level of cGMP and the mRNA and protein expressions of retinal AREG were decreased after treatment with JGSQP (all

P

<

0.05).

Conclusion:

2

JGSQP exhibited a significant inhibitory effect on axial length elongation with decreased expression of AREG in the retina

and normalized 4 HPAA-associated plasma hormones and the expression of cAMP and cGMP in GC-enhanced myopic guinea pigs.