ISSN 1062-3604, Russian Journal of Developmental Biology, 2006, Vol. 37, No. 5, pp. 330–333. © Pleiades Publishing, Inc., 2006.
Original Russian Text © A.V. Akhmadeev, 2006, published in Ontogenez, 2006, Vol. 37, No. 5, pp. 394–397.
The organizing inﬂuence of sex steroids is realized
at a certain developmental stage, which is called the
period of brain sexual differentiation. During this
period, speciﬁc features of neuroendocrine regulation
of gonadotropin secretion and steroid metabolism are
expressed (Reznikov, 1982). It is believed that the main
event of this period is the formation in the hypothala-
mus of two centers of regulation of gonadotropin secre-
tion: cyclic center located in the preoptic area and tonic
center located in the mediobasal part. Androgens
released by the testes during the period of brain sexual
differentiation determine the formation of “male
regime” of gonadotropin secretion. It was proposed that
the determining inﬂuence of an androgen or its metab-
olites can be realized in the amygdaloid complex to
form neuroendocrine centers in this complex, which are
capable of modulating the hypothalamus activity
(Akmaev and Kalimullina, 1993).
The dorsomedial nucleus is one of the main zones of
sexual dimorphism of the amygdaloid complex and is a
part of paleoamygdala (Akhmadeev and Kalimullina,
2004). Sex-related morphometrical, histophysiological,
and biochemical differences have already been
described in this nucleus (Akmaev and Kalimullina,
1982, 1993). However, it is still unclear whether test-
osterone administered during the period of brain sexual
differentiation may cause changes in neuronal organi-
zation of this nucleus.
The aim of this work was to study the effects of neo-
natal androgenization of female rats on characteristics
of the dorsomedial nucleus neurons.
MATERIALS AND METHODS
Studies were carried out on 30 sexually mature
Wistar rats, which were kept under identical conditions
of animal rooms with food and water
osterone propionate (a single dose of 1250
administered to 10 females on day 5 after birth. All ani-
mals (20 control and 10 neoandrogenized females)
were sacriﬁced at the age of 9 months observing all
rules of work with laboratory animals. Frontal sections,
m thick, were processed using the Golgi method
and embedded in Canada balsam. Neurons were identi-
ﬁed on the basis of classiﬁcation of Leontovich (1978).
The numbers of primary dendrites (d), free ends of neu-
ron dendrites (Bd), and all points of branching of the
neuron dendrites (Gd) were counted, the total length of
neuron dendrites (Ld), area of dendritic ﬁeld (Sda), and
length of the longest dendrites (C) were measured, and
the numbers of free ends and points of branching on
this dendrites were counted (Bdc, Gc). Also, we mea-
sured the length of the most branched dendrite (Cr) and
counted the numbers of its free ends and sites of
branching (Bdr, Cr). In neurons, we determined the
total length of all terminal branches of dendrites (Ldt).
We also used one arbitrary parameter: ratio of the num-
ber of free ends of the neuron dendrites to that of pri-
mary dendrites (Bd/d). The values were expressed in
arbitrary units obtained when using curvimeter and
planimeter. The results were statistically processed
using Statistica 5.5 software.
Analysis of presentation of the long-axonic rarely
branching neurons in the dorsomedial nucleus of con-
trol and neoandrogenized female rats has shown that all
main cell types were present: neuroblastoformal, short-
dendritic, and reticular.
Neuroblastoformal neurons of female rats are dis-
tinctly visualized when the materials were taken at the
estrus stage. In this case, groups of ﬁve to six cells were
often found. Neurons with rounded or oval bodies had
one or two dendrites of unequal length running from the
body in the opposite directions. In one cell only, could
Morphogenetic Effects of Neonatal Androgenization on Neuron
Dendroarchitectonics in Amygdala Dorsomedial Nucleus
A. V. Akhmadeev
Bashkir State University, ul. Frunze 32, Ufa, 450074 Russia
Received February 3, 2006; in ﬁnal form, May 2, 2006
—Speciﬁc features of neuron dendroarchitectonics in the amygdale dorsomedial nucleus were
described using the Golgi method after the injection of testosterone propionate at 1250
to females on the ﬁfth
day after birth.
: sex steroids, sexual differentiation of brain, neuronal organization, amygdaloid complex.