Research Journal of Recent Sciences ______ ______________________________ ______ ____ ___ ISSN 2277 - 2502 Vol. 2 ( ISC - 2012 ), 7 - 9 (201 3 ) Res.J. Recent .Sci. International Science Congress Association 7 Plasma Progesterone Levels of Corpus Luteum during Pregnancy in Microchiropteran Bat Hipposideros Speoris (Schneider) Watkar A. M. and Barbate M. P. D epartment of Zoology, Bhalerao Science College, Saoner, Dist. Nagpur, Maharashtra, INDIA Available online at: www.isca.in Received 30 th September 2012, revised 24 th December 2012, accepted 24 th Jan uary 201 3 Abstract The peripheral plasma progesterone concentrations were measured by radio immunoassay during the complete life span of corpus luteum in the Microchiropteran bat, Hipposideros speoris (Schneider). Soon after the ovulation during mid December all the females in the colony become pregnant irrespective of their age. Hence the corpus luteum formed during estrus period itself forms corpus luteum of pregnancy. Due to sinistral dominance the ovulation was restricted exclusively to the left side of the ovary and consequently the corpus luteum was formed in the same ovary every time and the progesterone concentration found t o be 16.8 ng/ml. Two types of corpus luteum intra - ovarian and extrovert have been observed. Some of the specimens collected during December and January showed an intra - ovarian large corpus luteum occupying major part of the ovary whereas in the other it wa s extrovert appearing as an umbrella during late December and the progesterone valus was elevated to 20.2ng/ml. During early January it reaches its maximum size just prior to implantation of the blastocyst, when it mushrooms out into a nearly spherical bal l, with its main bulk projecting out from the ovarian surface and the progesterone level was 28.8ng/ml. It develops maximally by the time the blastocyst reaches the uterus (mid - January) and was nearly as large as rest of the ovary attached to it by small p edicle, the progesterone level was rose and remained high till the regression (30.3 ng/ml). The commencement of regression of the corpus luteum was synchronised with the formation of the early trophoblastic placenta with shrinkage in its size was noticed u ntil it occurred as a small stump projecting from the surface of the ovary at the time when the chorio - vitelline placenta was well established during early and mid - February and a fall in the mean progesterone level was noted (3.1 ng/ml). The progesterone c oncentration rose steeply (30.1 ng/ml) and reached a plateau till March and April. Soon after the establishment of the chorio - allantoic placenta the corpus luteum became fibrous and was restricted to a corner. It was reabsorbed during mid - pregnancy (late M arch) and by late gestation (late April) it was completely lost in the stroma. Key words: Plasma progesterone, Hipposideros , corpus luteum, pregnancy . Introduction The order chiroptera is one of the most diverse taxa of the class Mammalia and as such e xhibits numerous specializations in female reproductive morphology and cyclocity. It is divided into two suborders, the Megachiroptera and the Microchiroptera. The bat, Hipposideros speoris belongs to the suborder Microchiroptera. Corpus luteum, is a dyna mic gland showing variations in size, structure and physiological activities in different stages of the pregnancy. This dynamic entity secretes progesterone as a principal hormone and estrogen, relaxin, oxytocin, neurophysin - 1, inhibin and vasopressin in l esser amount. The hormone progesterone influences secondary sex organs and is concerned with the progestational changes in the uterus. A perusal of available literature on the corpus luteum of bats reveals that no information on cellular components are ava ilable. The development of corpus luteum in bats belonging to the genera Vesperugu, Vespertilio and Plecotus was given by Vander Stricht et al 1 and followed by many others including 2 . Circulating levels of sex steroids reflect gonadal activity; their chan ges during the reproductive cycle have been studied extensively in several mammalian species 3 . In contrast, there are only a few reports concerning plasma steroids in bats; until the advent of sensitive radioimmunoassay techniques 4 , accurate measurement of steroids in the small blood samples obtainable from bats 5 was not feasible. In recent years, plasma progesterone levels during pregnancy have been measured in other bats also 6 . The original aim of this study was to evaluate the different levels of plasma progesterone in Hipposideros speoris (Schneider) so as to know what the changes occurs specially during pregnancy. As in other mammals the level of plasma progesterone is low during estrus period and it increases at term and rapidly decreases while the co rpus luteum regresses. Relatively low peripheral plasma progesterone level is an important prerequisite for initiation of labour and corpora lutea are the main sites of progesterone production during pregnancy 7 . Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ________ ISSN 2277 - 2502 Vol. 2 ( ISC - 2012 ), 7 - 9 (201 3 ) Res.J.Recent.Sci . International Science Congress Association 8 Material and Methods Hipposideros speoris is a common bat, which occurs, “throughout the greater part of India, specimens have been obtained from the Dehradun, from Chanda (Chandrapur) and other localities in the Deccan and from several places in Southern India” 8 , while Honacki J.H. ei al 9 mentio ned that this species was found in peninsular India and Srilanka. The leaf - nosed bat, Hipposideros speoris (Schneider) is selected for the present study because of its easy availability in the vicinity of Nagpur city , India . The specimens of Hipposideros were collected corresponding to its breeding habits i.e. from mid - December till full term pregnancy (April/May) with the help of a mist net from the natural population inhabiting abandoned mines in Khapa, Nagpur, Maharashtra. A field diary giving the sali ent features of each specimen was maintained and is appended (Table - 1). The animals were weighed and their crown - rump lengths were recorded after sacrificing by decapitation or with chloroform. The reproductive organs were dissected out and fixed in Bouin’ s fluid and 10% Neutral formalin and buffered formalin. For the determination of progesterone level in blood the bats would be anaesthetized by ether and 2 ml of blood would be drawn by cardiac puncture with 2 ml sterile syringe. The blood would be allowe d to clot at room temperature for half an hour and it would be used for RIA. Result s and Discussion The concenterations of plasma progesterone during pregnancy in Hipposideros speoris are shown in table 1. The data shows the various stages of pregnancy. D uring mid February when female is in estrus the plasma progesterone level is found to be 3.4 - 4.2ng/ml. The level increases late January i.e. formation of implanted bilaminar blastocyst takes place and the value of Plasma progesterone is now 26.3 - 29.6 ng/ml . During mid February the level declines to 14.8 - 17.0 ng/ml and so on up to 7.0 - 9.8 ng/ml till mid February during limb bud stage. From late February i.e. from limb bud stage till the full term pregnancy the plasma progesterone level inclines upto 43.8 - 44. 6 ng/ml. Transient peaks in plasma progesterone, such as we found in H. speoris at ovulation, and blastocyst formation have not been reported in Antrozous pallidus 10 , Tadarida brasiliensis Mexicana 11 or Macrotus californicus 12 ; in all of these bats, proge sterone levels are reported to rise subsequently. From the study it seems that the periovulatory rise in progesterone is due to the ovulatory surge of the pituitary Luteinizing Hormone, since similar LH - induced progesterone peaks occur in the rats 13 , mice 14,15 , hamsters 16 and guinea pigs 17 . The presence of discrete peak in plasma progesterone correlated with the beginning of blastocyst formation is strange; so far as we are aware, similar progesterone peaks have not been noted in other mammals. In fact, p rogesterone peaks do not occur when blastocysts are forming in rats, mice and guinea pigs; however, in these species, blastocyst form 24 hour or less before implantation, and the rise in the progesterone appears intuitively to be related to nidation. On th e other hand, transient peaks in plasma progesterone are not seen in carnivores 18 or in ungulates, although both have long preimplantation periods, and blastocysts formation and implantation are clearly separated. Table - 1 Values of the progesterone in H ipposideros speoris during pregnancy Sr. No. Status of Bats Date of Collection Values of Progesterone 1. Female in estrus 16.12.2010 3.4 - 4.2 ng/ml 2. Pre - implantation stage 28.12.2010 10.6 - 12.3 ng/ml 3. Pre - implantation stage 05.01.2011 15.3 - 16.1 ng/m l 4. Implanted bilaminar blastocyst 16.01.2011 28.2 - 33.5 ng/ml 5. Implanted bilaminar blastocyst 25.01.2011 26.3 - 29.6 ng/ml 6. Implanted bilaminar blastocyst 02.02.2011 14.8 - 17.0 ng/ml 7. Neural groove stage 12.02.2011 8.9 - 10.2ng/ml 8. Limb Bud Stage 20.02.2011 7.0 - 9.8 ng/ml 9. Limb Bud stage 26.02.2011 8.0 - 9.2 ng/ml 10. Limb Bud Stage 06.03.2011 11.3 - 12.8 ng/ml 11. Mid pregnancy 15.03.2011 15.6 - 19.4 ng/ml 12. Advanced Pregnancy 28.03.2011 23.6 - 25.8 ng/ml 13. Advanced Pregnancy 08.04.2011 33.5 - 34. 9 ng/ml 14. Advanced Pregnancy 18.04.2011 38.7 - 41.2 ng/ml 15. Advanced Pregnancy 30.04.2011 43.8 - 44.6 ng/ml Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ________ ISSN 2277 - 2502 Vol. 2 ( ISC - 2012 ), 7 - 9 (201 3 ) Res.J.Recent.Sci . International Science Congress Association 9 In both groups, the corpus luteum is the paramount source of progesterone, and plasma levels, which are quiet low at ovulation, rise steeply an d continuously during early pregnancy . A recent study showed that ovarian progesterone content did not differ between ovaries with or without corpora lutea during earlier stages of pregnancy 19 . Plasma progesterone levels rose very rapidly after implantati on and reached peak values in the final two weeks of pregnancy, inspite of the decrease in the levels during neural groove stage and limb bud stage. A significant decrease in plasma progesterone in A. pallidus during the middle third of pregnancy show a si milar but not statistically significant decline just after midpregnancy in P. pipistrellus 20 . Conclusion We saw no evidence of a prepartum decline in plasma progesterone, although such a decline has been reported in all other bats studied. 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