ISSN 10623604, Russian Journal of Developmental Biology, 2012, Vol. 43, No. 6, pp. 335–341. © Pleiades Publishing, Inc., 2012.
Original Russian Text © V.V. Porseva, A.A. Strelkov, V.V. Shilkin, P.M. Maslyukov, 2012, published in Ontogenez, 2012, Vol. 43, No. 6, pp. 405–412.
Over many decades, researchers in various fields
have studied the mechanisms of pain sensitivity. These
studies have demonstrated that pain sensitivity is medi
ated by several types of nociceptors such as mechano
salient, polymodal, and specific thermal and cold
receptors. Neuroscientists have yet to reveal specific
features of pain sensation that may be related to opening
of ion channels of the family of transitory receptor
potential (TRP)channels. The most wellknown
members of this group are TRPV1 vanilloid channels,
which are sensitive to capsaicin, heat, and low pH value.
Capsaicin receptors were found in Cfibers and their
branches formed by neurons of the sensory ganglia,
which transmit pain signals (Piper et al., 2000; Ma,
2002). Activation of capsaicinsensitive terminals
results in an increase in conductance of nonselective
cationic channels (Szolcszamyi, 2004; Bucelli et al.,
2008; Spiridonov et al., 2010) that enhances release of
substance P and calcitonin genrelated peptide.
In the present study, we examined agerelated
changes in the features of neurons containing calcitonin
generelated peptide in the sensory ganglia of the vagus
and thoracic nerves under conditions of capsaicin
induced afferentation deficit.
MATERIALS AND METHODS
Seventy 3, 10, 20, 30, 60, 90, and 180dayold
white female Wistar rats were used in the study. All
experiments were performed in accordance with the
“Rules for Studies Using Experimental Animals”
(order no. 775 from December 8, 1977, MZ USSR).
The animals were divided into two groups, control and
= 35. Two days after birth, the rats
of the experimental group were subjected to deafferen
tation using a single subcutaneous injection of capsaicin
(Nvanillylonanamide, Sigma) at a dose of 150 mg/kg
in a solution consisting of 96% ethyl alcohol : Twin80 :
0.9% NaCl at a ratio of 1 : 1 : 8. Neurons containing cal
citonin generelated peptide (CGRP) were morpho
metrically estimated in the caudal ganglion (low gan
glion) of the vagus nerve (CGVN) and the sensory gan
glion of the second thoracic nerve (SGTN). The
animals were euthanized using intraperitoneal urethan
injection at a dose of 3 g/kg followed by transcardial
perfusion with heparinized (5 U/L) saline and 4%
paraformaldehyde solution in 0.1 M phosphate buffer.
The ganglia were dissected and postfixed in the same
fixative for 2 h. Then, they were trice washed in phos
phate buffered saline (PBS) for 30 min and stored in
30% sucrose for 24 h. Twenty
mthick sections were
prepared from the fixed samples using a cryostat.
Neurons containing CGRP were detected using
labeled rabbit antibodies (Abcam, Great Britain) at a
dilution of 1 : 1000 according to the previously
described method (Masliukov et al., 2004; 2009). Sec
ondary antibodies conjugated with FITC fluorochrome
(Jackson, United States) emitted green fluorescence.
Immunohistochemical staining was performed in the
AgeRelated Changes in Sensory Neurons Containing Calcitonin
GeneRelated Peptide under Conditions
of Afferentation Deficit in Rats
V. V. Porseva, A. A. Strelkov, V. V. Shilkin, and P. M. Maslyukov
Yaroslavl State Medical Academy, Ministry of Health and Social Development of the Russian Federation,
ul. Revolyutsionnaya 5, Yaroslavl, 150000 Russia
Received June 24, 2011; in final form, December 2, 2011
—Morphological features of calcitonin generelated peptide (CGRP)immunoreactive neurons
were studied in the sensory ganglia of the vagus and thoracic nerves in 3, 10, 20, 30, 60, 90, and
180dayold rats under conditions of chemicallyinduced deafferentation. We found that, in rats, CGRP
containing neurons appeared in both ganglia immediately after they were born and their number decreased
with aging. Most of CGRPimmunoreactive neurons were small in size, i.e., up to 600
of capsaicin modified agerelated changes in the number of CGRPimmunopositive neurons. In the thoracic
nerve ganglion, the mean square of these cells and their number substantially decreased, whereas, in the vagus
nerve ganglion, positive cells were not observed.
: neuron, caudal ganglion, dorsal root ganglion, calcitonin genrelated peptide, capsaicin, ontog