Recent developments in the treatment of faecal incontinence

Effects of ovarian failure on submucosal collagen and blood vessels of the anal canal in postmenopausal women

BACKGROUND

Estrogen and progesterone receptors are expressed in the anal canal. Fecal control deteriorates after menopause. This phenomenon is related to decreased circulating levels of estrogen and progesterone due to ovarian failure at menopause.

AIM OF WORK

To study the effects of estrogen and progesterone on inflammatory cells, submucosal collagen fibers, and vascular plexus of the anal canal of postmenopausal women.

SUBJECTS AND METHODS

Experiments were performed on samples of anorectal tissue obtained from 40 women, 19 menstruating (group I), and 21 postmenopausal women (group II). Investigations included immunohistochemistry of estrogen and progesterone receptors and CD34.

RESULTS

In negative estrogen receptors (ER) and progesterone receptors (PR), inflammatory cells, submucosal blood vessels, collagen type I were nonsignificantly changed in postmenopausal women relative to menstruating women (P > 0.05) whereas, in positive ER and PR, inflammatory cells and collagen I were significantly increased and submucosal blood vessels were significantly decreased in postmenopausal women relative to menstruating women (P < 0.05).

CONCLUSION

Estrogen and progesterone, in menstruating women, produce beneficial effects by decreasing incidence of inflammation and increasing anal canal submucosal blood vessels number and collagen types I, thus both hormones have a positive effect on anal compliance and pressure.

Effects of ovariectomy and hormone replacement on submucosal collagen and blood vessels of the anal canal of rats

OBJECTIVE

To study the effects of oestrogen and progesterone on submucosal collagen fibres and vascular plexus of the anal canal.

MATERIALS AND METHODS

Experiments were performed on sections of the anal canal of ovariectomized rats following 28 daily subcutaneous injections of 17-beta oestradiol (n = 6, OVX + E, Group 1), medroxyprogesterone acetate (n = 6, OVX + P, Group 2), both drugs (n = 6, OVX + E + P, Group 3) or vehicle (n = 6, OVX) and after sham surgery without castration or injection (n = 6). Investigations included immunohistochemistry of oestrogen and progesterone receptors and collagen fibres, Western blot analysis of collagen types I and III and counting of perianal vessels by light microscopy.

RESULTS

There was positive immunostaining for oestrogen and progesterone receptors in the mucosa and for collagen types I and III in the submucosa in all samples. Type I collagen levels increased significantly with ovariectomy but were normalized with treatment with oestrogen and progesterone. Type III collagen levels decreased after ovariectomy. Administration of oestrogen and progesterone appeared to restore level to near sham values. Semi-quantitative measurement of Type I/III collagen ratios by signal intensity demonstrated a very high ratio after ovariectomy. This appeared to be restored by both oestrogen and progesterone administration either individually or in combination. Mean vessel count was significantly lower in sham animals compared to values in OVX animals (P = 0.006). However, while only oestrogen treatment increased significantly the number of vessels compared to sham animals (P = 0.04), replacement with progesterone did not affect and in combination with oestrogen reduced submucosal vessel number.

CONCLUSION

Oestrogen and progesterone have synergistic effects on collagen types I and III and probably antagonistic effects on the vascular plexus of the anal canal submucosa in adult female rats.