Testosterone, Cortisol, Oxytocin, HPA and HPG axis.

INTRODUCTION• Cortisol is released from adrenal cortex and plays a role in stress.• Testosterone is released from gonads and is related to aggression.

• Testosterone and cortisol have their parts to play in the Dual Hormone Hypothesis.

• Oxytocin is released from the posterior pituitary gland and is famously called the love hormone.

TESTOSTERONE

• It is a steroid hormone from the androgen group.

• Key role- in the development of male reproductive tissues (testis, prostate) as well as promoting secondary sexual characteristics –increased muscle, bone mass etc .

• Plays a role in aggression and dominance.• Helps to spark competitiveness and boost self-

esteem.

Dual Hormone Hypothesis• The dual hormone hypothesis posits that basal cortisol and testosterone have

a joint effect on motivational and behavioral systems implicated in dominance and aggression, such that traits generally associated with high testosterone manifest more in individuals with low basal cortisol levels.

• Because dominance is related to gaining and maintaining high status positions in social hierarchies, the findings suggest that only when cortisol is low should higher testosterone encourage higher status. When cortisol is high, higher testosterone may actually decrease dominance and in turn motivate lower status.

CORTISOL• Cortisol is a glucocorticoid hormone synthesized from the middle

area of the adrenal cortex within the adrenal gland. • It is released in response to stress and low blood glucose• While cortisol’s primary targets are metabolic, it also affects ion

transport, the immune response, increase blood sugar through glucogenesis.

• Sleep deprivation can cause cortisol levels to increase by over 50%. It causes the depletion of neurotransmitters, mood regulating hormones, and this has the effect of making people more vulnerable to becoming easily depressed. Impaired cognitive ability, out of check emotions, and poor judgment or poor logic also results from sleep deprivation.

CERTAIN FACTS ON CORTISOL• Prolonged exposure to high cortisol levels can lead to break down of muscle,

excessive epinephrine release, hyperglycemia, weakening of bone, destruction of the immune system, inhibition of reproductive function, and other complications.

• Expressed at the highest levels in the early morning, cortisol’s main function is to restore homeostasis following exposure to stress The effects of cortisol are felt over virtually the entire body and impact several homeostatic mechanisms.

• Cortisol works with epinephrine (adrenaline) to create memories of short-term emotional events; The hippocampus, the region of the brain where memories are processed and stored, contains many cortisol receptors. While normal cortisol levels have no adverse effects on the hippocampus, excess cortisol overwhelms the hippocampus and actually causes atrophy However, long-term exposure to cortisol damages cells in the hippocampus this damage results in impaired learning. Furthermore, it has been shown that cortisol inhibits memory retrieval of already stored information.

OXYTOCIN• It is a neuromodulator.• It is produced in supraoptic and paraventricular

nuclei of the hypothalamus by the nerve axons and stored in the posterior pituitary gland.

• It is a peptide of nine amino acids.

Functions:• The letdown reflex• Uterine contraction

• Social behaviour and wound healing• Modulation of HPA axis activity

• Interaction of vasopressin.

Facts Emphasizing Oxytocin

• Dopamine and oxytocin receptors produce a euphoria like state that may account for “love at first sight” phenomenon.

• Oxytocin have been found to be related to trust (not alone romantic but also business and occupational)

• Holding grudge produces cortisol and diminishes oxytocin

• After being called the love hormone, the trust hormone, the cuddle hormone, a 2009 study finds oxytocin associated to envy and jealousy

WHAT IS HPA AXIS?

• HPA is also known as Limbic-Hypothalamic-Pituitary-Adrenal-Axis.

• HPA Axis is a complex set of direct influences and feedback among the hypothalamus, the pituitary and the adrenal glands.

•The A stands for the adrenal glands. We each have two of them located just above the kidneys. Although physically separate from the hypothalamus and pituitary glands, they are deeply connected. •Function-The adrenals produce even more hormones than the pituitary gland does – steroid hormones like cortisol, sex hormones like DHEA (Dehydroepiandrostenedione),&stress hormones like adrenaline and dopamine. The hormones produced by the adrenals control chemical reactions over large parts of our bodies, (‘fight-or-flight’ response).

•The H in HPA stands for Hypothalamus, a small part of the brain that has important roles.•Function-is to send messages from the brain to the adrenals,the pituitary and other organs, so it is usually considered to be the starting point in the HPA axis. •It is ultimately responsible for things like your circadian rhythm, your body temperature and your energy levels.

•The P stands for the pituitary gland is a pea sized gland but it produces an extraordinary number of hormones that our bodies need. •Function-produces vital hormones like Growth Hormone, Anti-Diuretic Hormone and Luteinizing Hormone. It is physically connected to the hypothalamus and is located at the base of the brain.

HPA Axis

HPA AXIS

What is HPG Axis?

The Hypothalamic–Pituitary–Gonadal axis (HPG axis) refers to the effects of the Hypothalamus, Pituitary glands and Gonads.

The HPG axis comprises of the interaction between the hypothalamus, pituitary gland and the gonads. The system works together to regulate development, reproduction, ageing and many other body processes. It’s regulation relies upon a number of complex negative feedback loops which when lost result in disease.

HPG Axis

HYPOTHALAMUS

Gonadotropin-releasing hormone (GnRH) is secreted by GnRH-expressing neurons.

Gonads

estrogen and testosterone.

Anterior portion of the PITUITARY

luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

HYPOTHALAMUS

Gonadotropin-releasing hormone (GnRH) is secreted by GnRH-expressing neurons.

Anterior portion of the PITUITARY

luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

MALE HPG AXIS

FEMALE HPG AXIS

Interaction between HPG &HPA axes

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