In dian Journal of Experimental Biology Vol. 40, November 2002, pp. 1245- 1249 Mentha piperita (Linn) le af extract provides protection against radiation induced alterations in intestinal mucosa of Swis s albino mice R M Samarth , M R Saini , J Maharwal, A Dhaka & As hok Kumar* Rad iatio n & Cancer Bi ology Laboratory , Depa rt ment of Zoology, Univers ity of Rajasthan, Jaipur 302004, India Rece ived 23 April 2002: rev ised 13 AII g II s/ 2002 Intestin al prot ec tion in mice agai nst radiation injury by M. piperila (I g/kg body weight/day) wa s studied from da y I to da y 20 after whole body gamma irrad i at ion (8 Gy) . Villus height , goblet ce ll s/villus sec ti on, to tal ce ll s, milOtic ce ll s and dead ce ll s/crypt sec tion in th e jejunum arc good parameters for the assessme nt of rad i at ion damage. There was sig ni fi cant decrease in th e villus height , number of IOtal ce ll s and mito ti c ce ll s/crypt sec ti on, whereas goblet ce ll s and dead cell s showed sig nifi ca nt in crease after irradiatio n. Me lllha pretreatme nt resu lt ed in a significant in crease in villus heig ht , total cel ls and mit otic ce ll s, whereas go bl et ce ll s and dead ce ll s showed a signifi ca nt decrease fr om res pective irradiated co nt rols at eac h aut opsy day. The res ult s suggest th at Melllha pretrea tm e nt prov id es protec ti on against radiation induced alt e ration s in int es ti nal mu cosa of Swi ss albin o mi ce. Th e sma ll int es tin e represe nt s one of the major dose limitin g no rm al ti ss ues in rad io th erapy because of it s hi gh radiosensitivity. Reducing the damage to small intestine usin g chemical protectors, parti c ul arl y dur- in g rad ioth erapy of th e pelvic and ab do min al cancers, can increase th e patient 's tol erance to radiation . It is ge nerally accepted th at the cause of death after a dose of radia ti on less than 5 Gy that resu lt s in th e death of a nim als in 10-15 days is because of hematopoietic fai lure. However, it is an es tablished fact that th e gas- trointestinal sy ndrome after total body irradiati on also includes hematopo ietic compone nt s t - 3 . Thus, in addi - tion to stimul ation of hematopoi etic ce ll s, o th er path- ways may be required to achieve th erapeutic efficacy in radi oth erapy. The Mentha tr ea tm e nt protects th e hematological consti tu e nt s a nd ser um phosphatases ac tivity in Swiss albino mice agai nst ga mm a irr ad i a- ti on 4 .5. Th erefor e, th e prese nt stud y has been under- taken to determine the radioprotective effect of leaf extract of Mentha piperita Linn. on mouse jejunum by usin g parameters like vi llu s heig ht , goblet ce ll s/v illu s sec ti on, total ce ll s, mitot ic ce ll s a nd dead ce ll s/c rypt section as end point s. Materials and Methods An illl als-Ad ult male Swiss albino mice (6-8 weeks o ld , weighing 25±2 g) mainta in ed in th e animal *Corresponde nt author Phone: 09 1-1 4 1-7111 58 Fax: 09 1- 14 1 -7 01137 E-mail: mamsjpr@hotmail.com house as an inbred colony (proc ured fro m Hamdard Univers it y, De lhi ) were used. These were ma in tained on sta nd ard mice feed a nd water ad libitum . irradiation- The Cobalt teleth erapy unit (AT C- C9) at cancer trea tm e nt centre, Rad io th erapy Depart- ment, SMS Medical Co ll ege a nd Hospital, Jaip ur was use d fo r irrad i at ion. Unanaesthetised mice res trained in we ll- ve ntil ated Perspex boxes were exposed to whole-body gam ma radiation (8 Gy) at a di stance (SSD) of 77.5 cm from the source to deliver th e dose- rate of 1.5 9 Gy/min. Mentha extract (ME)-F resh leaves of Mentha piperita Linn. fRUBL-19443], co ll ected loca ll y were a ir dried, powdered and ex tr acted with double di s- tilled water (DDW) by refluxin g fo r 36 hI' ( 12 hr x3) at 80°C. The extract thus obta in ed was vac uum evaporated so as to make it in powder form. The ex- tract was red issolved in DOW just before oral ad mini - stration. Experim ental des ign-Mice selected from inbred colony were divided into two group s. Anima ls of on e group we re administered ME ora ll y ( I g/kg body we ight/d ay) fo r three consecutive days to serve as expe rim e nt al, whi le the oth er gro up received DOW (vo lume eq ual to ME) to serve as contro l. On 3rd da y, after 30 min of above treatments an imals of both the gro up s we re ex posed to 8 Gy gamma radiation. Mi ce from bo th th e gro up s were a ut opsi ed at I, 2, 5, 10 and 20 days of post-irradiation. A minimum of 5 animals from each gro up were sacr ifi ced and jejunum was fi xe d in Bouin 's fixative. Sections (5 1-lin thick )