Lonidamine (LND) or [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid] is an
anticancer and antispermatogenic drug that exerts a large number of effects on
tumor cells and germ cells. Sexually mature male Sprague-Dawley rats were housed
at 22 degrees C on a 12-h light/12-h dark cycle 1 week before the experiments,
with free access to food and water. LND was suspended in 0.5% methylcellulose at
a concentration of 10 mg/mL and administered orally at the dose of 10 mL/kg
(b.w.) as a single dose. Control rats received an equal amount of vehicle. Testes
were removed, fixed for 24 h in 2% glutaraldehyde and 2% paraformaldehyde in 0.1
M sodium phosphate (pH 7.2 at 22 degrees C), rinsed with the same buffer, and
stored at room temperature. From each sample, a block of tissue was removed by
sectioning through the organ. After dehydration in ethanol at increasing
concentrations (70-100%), each block was embedded in paraffin and serial 5 mm
thick sections were cut using a rotatory microtome. The immunoreactivity for NTs
has been observed in spermatogonia of untreated rats, while the rats treated with
LND showed an immunohistochemical localization in all the stages of germinal
cells. The generally well-expressed immunoreactivity for the neurotrophins
receptors in treated rats observed in our study is presumably attributable to
alterations of the receptors' structure and/or expression leading to changes of
the activity, affinity, localization or protein interactions that may depend on
sensitization of ion channels (induced by LND). Neurotrophins (NTs) appear to be
interesting proteins for the modulation of sperm maturation and motility with a
prominent role for the nerve growth factor (NGF), that may exert an autocrine or
paracrine role. We therefore investigated the location and distribution of
immunoreactivity for some neurotransmitters (SP, VIP, CGRP, nNOS, Chat),
neurotrophins (NGF, BDNF, NT-3) and their own receptors (TrKA, TrKB, TrKC, p75)
in the seminiferous tubules of male rats treated by LND in the light of the
literature on this topic.
