Hormones (Meaney)

Question 1

Introduction (Hormones are secreted by the body’s endocrine system…)

Answer 1

Hormones are secreted by the body’s endocrine system (glands that secret chemicals directly into the bloodstream).

Hormones are chemicals released in order to regulate medium & long term changes in the body (e.g. mood, attention, etc.)

Question 2

Role of the hormone glucocorticoid

Answer 2

A hormone that influences human behavior is glucocorticoids (plays a role in altering and stimulating a stress response).

Question 3

Meaney Aim

Answer 3

To determine the effect of glucocorticoids (stress hormones) on memory

Question 4

Meaney Procedure

Answer 4

1. Newborn rats handled daily by the researchers for three weeks - from the day of their birth until weaning.
2. During this time they were taken away from their mothers for 15 minutes and placed in a container.
3. They were brushed for an intense 15 minutes to simulate the grooming of the mother rat.
4. Control group: The rats in the control group were taken away from their mother but there was NO HANDLING by the researchers.
5. To test the effect of these elevated rates of stress hormones over their lifetime, two-year-old rats were put into a pool of milky water with a platform. Meaney tracked the route of the rats as they sought out the platform based on the rats’ memories of previous attempts to escape the water.

Question 5

Meaney findings

Answer 5

High levels of glucocorticoids (stress hormone) affected the rats until old age —> hippocampal neuron loss and cognitive impairments in aging (this was not present in rats that received the stroking) — the extra stroking “turns on” genes that can prevent stress in later life (epigenetics) which leads to a healthier rat

Question 6

Meaney link to role of hormones

Answer 6

The role of the stress hormone, cortisol, releases from the adrenal glands within the rats and heighten stress response - though we see that the 15-min grooming process that mimicked a high-nurturing mother allowed them to be better equipped to handle stress

Stress Circuit: Cortisol released from adrenal glands in response to stress signals -> hippocampus sends message to hypothalamus shuts down the “fight or flight” response