INTEGRIDADE E FUNCIONALIDADE DOS ... - Ainfo - Embrapa

Abstract 195
_____________________________________________________________________
ABSTRACT
AZEVEDO, H. C. Spermatic integrity and function in ram cryopreserved semen
after incorporation of cholesterol, desmosterol, oleic-linoleic acid and αlactalbumin.
Botucatu, 2006. 195p. Thesis (PhD) – College of Veterinary
Medicine and Animal Science, Sao Paulo State University.
In order to evaluate the protecting action of some substances on ram
spermatozoa, semen samples of 25 rams were collected and submitted to
cryopreservation after treatment with cholesterol, desmosterol, oleic-linoleic
acid or α-lactalbumin. Before the processing and after the procedures of
cooling, freezing-thawing and incubation, semen was evaluated as to kinetics
by subjective and computerized analyses (CASA), morphology, simultaneously
to plasma membrane integrity (PMI), acrosome integrity (ACI) and mitochondrial
membrane potential (MMP) by isothiocyanate-conjugated Pisum sativum (FITC-
PSA), propidium iodide (PI) and JC-1 combination and as to sperm capacitation
and acrosome reaction determined by chlortetracycline (CTC) assay. The
influence resulted from the additives in a few parameters was not enough to
suggest the superiority of any treatments. The cryopreservation process,
especially the freezing-thawing, promotes damages to kinetics, PMI, ACI, MMP
and induces accelerated capacitation and acrosome reaction in spermatozoa.
Differences among groups of rams were observed regarding capacitation status
in fresh semen as well as the sensibility of their semen to cryoinjury and
cryocapacitation. Higher and more accelerated capacitation-like changes were
observed in groups of rams presenting lower plasmatic membrane
cryoresistance after thawing. The segregation of rams in different levels of PMI
influenced the behavior of several other parameters. It was concluded that
cholesterol, desmosterol, oleic-linoleic acid and α-lactalbumin do not protect the
ram semen against the cryoinjuries as well as freezing-thawing is more harmful
than cooling. Important differences among groups of individuals were noticed as
for the spermatozoa resistance to the damages provoked by cryopreservation
such as the cryocapacitation susceptibility.
Key Words: semen, ram, cryopreservation, cholesterol, desmosterol, oleic-
linoleic acid, α-lactalbumin, sperm capacitation, acrosome reaction and
spermatic membranes integrity.