Mind your Hormones!
Of all human emotions and behaviors, compassion may be the most hormonal, at least if you believe the
scientific literature. Or to put it more precisely, many scientific studies find strong evidence that compassion
and its constituent components, such as empathy, are both influenced by endocrine factors and influence
them in turn. It is these bi-directional relationships between the human endocrine system and compassion that
are the focus of this chapter.
Defining Terms
Endocrinology
is the field of medical science that focuses on all things related to the production, release,
uptake and physical effects of hormones.
Hormones
, in turn, are substances, usually peptides or steroids,
which are produced by one tissue and conveyed by the bloodstream to another tissue to effect physiological
activity, such as growth or metabolism within that second tissue. Classically, hormones were understood to be
produced by specialized glands in the body from whence they floated through the blood to impact any number
of other bodily tissues.
But as with many things in science, ongoing discoveries have complicated this simple picture in ways that are
directly relevant to our current discussion. For example, substances that are hormones in the body often
function as neurotransmitters in the central nervous system (CNS). A classic example of this is the peptide
hormone oxcytocin, of which we’ll have much to say in this chapter. Oxytocin is produced primarily in the
hypothalamus, an ancient area at the bottom of the brain that produces many other hormone-like substances
that have profound behavioral effects. For many years, oxytocin was known to medicine primarily for its roles
in promoting childbirth and nursing. In this role, oxytocin is a classic hormone. It is produced in one tissue (the
brain) and floats through the blood to other tissues (the uterus and breast) where it has its effects. But
discoveries over the last ten years or so have demonstrated that oxytocin also has profound effects on the
brain directly related to social behavior, including empathy, in humans and other mammals
,
. In
this role oxytocin behaves more like a neurotransmitter than a classic hormone. Oxytocin is far from alone in
being a hormone with multiple other talents. For example, another classic hormone that we’ll discuss in this
chapter, cortisol, has so many effects on the immune system that one could almost consider it to be an
immune molecule as much as an endocrine one.
The Endocrine System from 30,000 Feet
The intricacies of the body’s vast and complex endocrine pathways are far beyond our purview in this brief
chapter. So we’ll have to make do with a simplified view that merely touches upon major aspects of hormonal
organization and function – a 30,000-foot view of the major landmarks of endocrine geography.
All areas of the brain are likely to impact hormonal functioning one way or another. But the
hypothalamus
is
especially relevant to endocrinology because it serves as the headgate for most of the body’s major hormonal
pathways. It is also the area of the brain most intimately connected, both functionally and physically, with the
body’s prime endocrine organ, the
pituitary gland (
. In response to signals from other brain areas, as
well as from the body, the hypothalamus secretes a number of hormones that float down a small and
specialized bloodstream connection to the anterior (or forward) part of the pituitary gland. These hormones
stimulate the production and release of a wide range of other hormones by the
anterior pituitary, or
adenohypophysis
, which, in turn, influence many other bodily glands and organs, including the thyroid gland,
the adrenal glands and the sexual organs. The second prime endocrine role of the hypothalamus is to
produce
oxytocin
and the closely related hormone
vasopressin
. These two hormones are transported down
nerve axons into the posterior pituitary gland, also known as the
neurohypophysis
, from which they are
released.
Because this chapter focuses on the endocrinology of compassion, rather than endocrinology in general, we
can only make passing reference to many of the important hormones secreted by the anterior pituitary,
including
thyroid-stimulating hormone (TSH)
, which regulates the thyroid gland, and
follicle-stimulating
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