During the pandemic lockdown, as couples have been
forced to spend days and weeks in one another’s company, some have found their
love renewed while others are on their way to divorce court. Oxytocin, a
peptide produced in the brain, is complicated in that way: a neuromodulator, it
may bring hearts together or it can help induce aggression. That conclusion
arises from unique research led by Weizmann Institute of Science researchers in
which mice living in semi-natural conditions had their oxytocin producing brain
cells manipulated in a highly precise manner. The findings, which were
published in Neuron, could shed new light on efforts to use
oxytocin to treat a variety of psychiatric conditions, from social anxiety and
autism to schizophrenia.
Much of what we know about the actions of
neuromodulators like oxytocin comes from behavioral studies of lab animals in
standard lab conditions. These conditions are strictly controlled and
artificial, in part so that researchers can limit the number of variables
affecting behavior. But a number of recent studies suggest that the actions of
a mouse in a semi-natural environment can teach us much more about natural
behavior, especially when we mean to apply those findings to humans.
Prof. Alon Chen’s lab group in the Institute’s
Neurobiology Department have created an experimental setup that enables them to
observe mice in something approaching their natural living conditions — an environment
enriched with stimuli they can explore — and their activity is monitored day
and night with cameras and analyzed computationally. The present study, which
has been ongoing for the past eight years, was led by research students Sergey
Anpilov and Noa Eren, and Staff Scientist Dr. Yair Shemesh in Prof. Chen’s lab
group. The innovation in this experiment, however, was to incorporate
optogenetics — a method that enables researchers to turn specific neurons in
the brain on or off using light. To create an optogenetic setup that would
enable the team to study mice that were behaving naturally, the group developed
a compact, lightweight, wireless device with which the scientists could
activate nerve cells by remote control. With the help of optogenetics expert
Prof. Ofer Yizhar of the same department, the group introduced a protein
previously developed by Yizhar into the oxytocin-producing brain cells in the
mice. When light from the wireless device touched those neurons, they became
more sensitized to input from the other brain cells in their network.
“Our first goal,” says Anpilov, “was to reach that
‘sweet spot’ of experimental setups in which we track behavior in a natural
environment, without relinquishing the ability to ask pointed scientific
questions about brain functions.”
Shemesh adds that, “the classical experimental setup
is not only lacking in stimuli, the measurements tend to span mere minutes,
while we had the capacity to track social dynamics in a group over the course
of days.”
Delving into the role of oxytocin was sort of a test
drive for the experimental system. It had been believed that this hormone
mediates pro-social behavior. But findings have been conflicting, and some have
proposed another hypothesis, termed “social salience” stating that oxytocin
might be involved in amplifying the perception of diverse social cues, which
could then result in pro-social or antagonistic behaviors, depending on such
factors as individual character and their environment.
To test the social salience hypothesis, the team used
mice in which they could gently activate the oxytocin-producing cells in the
hypothalamus, placing them first in the enriched, semi-natural lab
environments. To compare, they repeated the experiment with mice placed in the
standard, sterile lab setups.
In the semi-natural environment, the mice at first
displayed heightened interest in one another, but this was soon accompanied by
a rise in aggressive behavior. In contrast, increasing oxytocin production in
the mice in classical lab conditions resulted in reduced aggression. “In an
all-male, natural social setting, we would expect to see belligerent behavior
as they compete for territory or food,” says Anpilov. “That is, the social
conditions are conducive to competition and aggression. In the standard lab
setup, a different social situation leads to a different effect for the
oxytocin.”
If the “love hormone” is more likely a “social
hormone,” what does that mean for its pharmaceutical applications? “Oxytocin is
involved, as previous experiments have shown, in such social behaviors as
making eye contact or feelings of closeness,” says Eren, “but our work shows it
does not improve sociability across the board. Its effects depend on both
context and personality.” This implies that if oxytocin is to be used
therapeutically, a much more nuanced view is needed in research: “If we want to
understand the complexities of behavior, we need to study behavior in a complex
environment. Only then can we begin to translate our findings to human
behavior,” she says.
Source: https://myfusimotors.com/2020/06/23/what-does-the-love-hormone-do-its-complicated/
No comments:
Post a Comment