Fish study shows role of estrogens in sense of smell

Date:
January 19, 2022
Source:
University of Exeter
Summary:
Steroid estrogens play an important role as embryos develop a sense
of smell, new research shows. The study, which examined zebrafish
embryos, discovered a type of astrocyte glial cell that is new to
science, and have been named estrogen responsive olfactory bulb
(EROB) cells.



FULL STORY ========================================================================== Steroid estrogens play an important role as embryos develop a sense of
smell, new research shows.


==========================================================================
The study, which examined zebrafish embryos, discovered a type of
astrocyte glial cell that is new to science, and have been named estrogen responsive olfactory bulb (EROB) cells.

estrogens are known for their roles as signalling hormones in
the development of sex, but the study shows that prior to sexual differentiation (when the sex of an individual becomes fixed), a small
group of cells in the region of the brain where the sense of smell
develops, the olfactory bulb, are responsive to estrogen.

The research, led by Dr Aya Takesono of the University of Exeter,
employed a genetically engineered (transgenic) zebrafish, developed in
the laboratories of Professor Tyler and Dr Kudoh at Exeter, that enables
cells and tissues responding to estrogen to be seen via microscopy
imaging for this work.

Using this transgenic zebrafish, together with chemical and genetic
methods to manipulate these estrogen responding cells, has revealed a
new function of estrogens during embryonic brain development.

Dr Takesono said: "Previous studies in mice have shown that estrogen is important for development of the somatosensory cortex of the brain and
for establishing sexual dimorphic brain tissues that mediate reproductive functions and behaviour in later life.



==========================================================================
"In this study, however, we show that the olfactory bulb is the one of
earliest parts of the developing brain that is responsive to estrogens
in the zebrafish embryo.

"We further show that our newly discovered EROB cells mediate the
estrogen driven instruction for development of olfactory sensory system
in the embryonic brain." Tracing the development of these EROBs using
various cellular and imaging methods showed they interact with olfactory sensory neurons and their loss - - or disturbance of their interactions
with the surrounding neurons -- disrupts establishing inhibitory neural connections in the olfactory glomeruli.

Using another transgenic zebrafish, this time one that detects both neural activity (via the detection of calcium produced when nerve cells fire)
and estrogen responses, the study shows that estrogen signalling alters neuronal activity in the olfactory bulb through these newly identified
EROBs which in turn affects odorant-response behaviour.

This study provides evidence that estrogens act on EROB glia to regulate olfactory circuits with important consequences for the sense of smell
in later life.

Professor Tyler, senior author in the work, said: "This work identifying
new embryonic brain cells involved in the development of the sense of
smell in fish opens up a major new research area for us.

"Surface waters receive many human-made chemicals that mimic estrogens and
an intriguing question we wish to now address is whether these chemicals
affect the function of the EROB glia in embryogenesis and thus alter the
sense of smell, as this could have major fitness consequences for fish." special promotion Explore the latest scientific research on sleep and
dreams in this free online course from New Scientist -- Sign_up_now_>>> academy.newscientist.com/courses/science-of-sleep-and-dreams ========================================================================== Story Source: Materials provided by University_of_Exeter. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Aya Takesono, Paula Schirrmacher, Aaron Scott, Jon M. Green,
Okhyun Lee,
Matthew J. Winter, Tetsuhiro Kudoh, Charles R. Tyler. Estrogens
regulate early embryonic development of the olfactory sensory
system via estrogen- responsive glia. Development, 2022; 149 (1)
DOI: 10.1242/dev.199860 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220119121358.htm

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