MODULATION OF PROSTAGLANDIN E2 (PGE2) MEDIATED PATHWAY IN THE ECLOSION BLOCKING EFFECT OF TERPENOID FRACTION OF ARTEMISIA NILAGIRICA IN RHIPICEPHALUS (BOOPHILUS) ANNULATUS
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Date
2018
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Prostaglandins are a group of important cell signaling molecules
involved in the the regulation of ovarian maturation, oocyte development,
egg laying and associated behaviours in invertebrates. However, the
presence of prostaglandin E2 (PGE2), the key enzymes for biosynthesis and
its interference by drugs have not been investigated in the ovary of ticks.
The present study was undertaken to assess the modulation of PGE2
mediated pathway in the eclosion blocking effect of terpenoid fraction
isolated from Artemisia nilagirica in Rhipicephalus (Boophilus) annulatus
ticks. The dried hexane fraction of ethanolic extract of aerial parts of A.
nilagirica was used for isolation of terpenoid fraction by Herz-Hogenauer
method. The acaricidal activity of the terpenoid fraction was evaluated by
adult immersion test. The chemical profiling of the extract/fraction was
done by HPTLC and GCMS analysis. Localization of the cyclooxygenase1
and prostaglandin E synthase enzymes in the ovaries of control and treated
ticks were done by immunohistochemistry. The vitellogenin concentration
in hemolymph also was assayed by indirect ELISA. The terpenoid fraction
of A.nilagirica elicited a concentration dependent percentage inhibition of
fecundity and hatching rate in the laid eggs of R (B.) annulatus. The HPTLC
fingerprint profiling of terpenoid fraction revealed the presence of nine
polyvalent compounds. Twenty two terpenoid compounds were identified
in the terpenoid fraction based on mass spectral matching with commercial
libraries (NIST, Wiley). Presence of PGES in stage III oocytes in control
ticks was confirmed by immunohistochemistry whereas immunereactivities
were absent in the vitellogenic oocytes of flumethrin and terpenoid fraction
treated ticks. The intensity of immunoreactivities were too low to be
detected in vitellogenic oocytes of both control and treated ticks. The levels
of PGE2 were below detection limit in in the ovaries of flumethrin treated
ticks. The levels were significantly lower in ovaries of terpenoid fraction
than control ovaries. No significant difference in the concentration of Vg
was observed in the hemolymph of treated and control ticks.
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