ABSTRACT
Senna siamea is a medicinal plant native to Asia. It is widely distributed in different parts of Nigeria, where it is employed in traditional ethno-medicinal and ethno-veterinary practices for a variety of ailments. In this study, the effect of S. siamea on smooth muscle contractility of the ileum in an organ-bath was demonstrated as well as evaluating the histology and histochemistry of the colon in opioid-induced constipation in Wistar rats. Thirty (30) female Wistar rats with mean weight of 126.7g were used in this work. They were randomly grouped into five groups (IV) of six rats each and treated as follows; Group I received Normal saline, Group II received Loperamide(3mg/kg), Group III received S. siamea(300mg/kg) and Loperamide(3mg/kg), Group IV received Loperamide and S. siamea, Group V received Bisacodyl 5mg/kg (Standard laxative). Constipation was induced in Group II for 6-days using loperamide at 3mg/kg. There was a significant improvement in the nature of stool (size and texture) of animals treated with extract (S. siamea) after induction with loperamide. Results obtained at the in vitro phase (contractility experiment) of this work showed that S. siamea possess laxative effect by relaxing the rapid contraction of the ileum of wistar rats. In this study, S. siamea was observed to relax the contractility of ileum in organ-bath (tyrode solution) which was similar to what was observed when loperamide was administered. Senna siamea was effective in treating opiate-induced constipation at the in-vitro and in-vivo phase as it ameliorate the constipative effects of loperamide. In addition, Senna siamea improved evacuation of stool by reducing the muscle tone of the Gastro-intestinal tract. There was no statistical significant difference in stool weight, organbody weight ratio, and change in body weight of experimental animals at P≤0.05. Histological analysis using Heamatoxylin and Eosin stain revealed several enlarged and numerous goblet cells around the crypt of Lieuberkuen in the loperamide treated group (loperamide 3mg/kg) while goblet cells of extract treated groups(S.siamea 300mg/kg) were fewer and reduced in size which could be attributed to the laxative effect of the extract on the mucosa of the GIT. Goblet cells of bisacodyl (standard laxative) 5mg/kg treated group appeared fewer and enlarged. PAS was used to specifically stain neutral mucin. Mucous cells in loperamide treated group stained PAS positive with numerous and enlarged goblet cells. This is in sharp contrast with results obtained in extract treated group as fewer stained mucous cells were observed. Based on our observations, we therefore conclude that Senna siamea had laxative effect on the colon of constipated wistar rats by suppressing goblet cell production of mucous, improvement of faecal evacuation as well as its relaxing effect on the ileum.