T. Rhen et D. Crews, Distribution of androgen and estrogen receptor mRNA in the brain and reproductive tissues of the leopard gecko, Eublepharis macularius, J COMP NEUR, 437(4), 2001, pp. 385-397
Incubation temperature during embryonic development determines gonadal sex
in the leopard gecko, Eublepharis macularius. In addition, both incubation
temperature and gonadal sex influence behavioral responses to androgen and
estrogen treatments in adulthood. Although these findings suggest that temp
erature and sex steroids act upon a common neural substrate to influence be
havior, it is unclear where temperature and hormone effects are integrated.
To bogie to address this question, we identified areas of the leopard geck
o brain that express androgen receptor {AR) and estrogen receptor {ER) mRNA
. We gonadectomized adult female and male geckos from an incubation tempera
ture that produces a female-biased sex ratio and another temperature that p
roduces a male-biased sex ratio. Females and males from both temperatures w
ere then treated with equivalent levels of various sex steroids. Region-spe
cific patterns of AR mRNA expression and ER mRNA expression were observed u
pon hybridization of radiolabeled (S-35) cRNA probes to thin sections of re
productive tissues (male hemipenes and female oviduct) and brain. Labeling
for AR mRNA was very intense in the epithelium, but not within the body, of
the male hemipenes. In contrast, expression of ER mRNA was prominent in mo
st of the oviduct but not in the luminal epithelium. Within the brain, labe
ling for AR mRNA was conspicuous in the anterior olfactory nucleus, the lat
eral septum, the medial preoptic area, the periventricular preoptic area, t
he external nucleus of the amygdala, the anterior hypothalamus, the ventrom
edial hypothalamus, the premammillary nucleus, and the caudal portion of th
e periventricular nucleus of the hypothalamus. Expression of ER mRNA was sp
arse in the septum and was prominent in the ventromedial hypothalamus, the
caudal portion of the periventricular nucleus of the hypothalamus, and a gr
oup of cells near the torus semicircularis. Many of these brain regions hav
e been implicated in the regulation of hormone-dependent, sex-typical repro
ductive and agonistic behaviors in other vertebrates. Consequently, these n
uclei are likely to control such behaviors in the leopard gecko and also ar
e candidate neural substrates for mediating temperature effects on behavior
. J. Comp. Neurol. 437:385-397, 2001 (C). 2001 Wiley-Liss, Inc.