lecture 7 part II

Question 1

T or F: The hormonal events of gestation and birth play an important role in turning on maternal care behaviors

Answer 1

true

Question 2

hormones important for rat gestation

Answer 2

• progesterone
• estradiol
• prolactin
• placental lactogens

Question 3

progesterone

Answer 3

• Increases across gestation
• Important for development of the fetus and keeping the fetus inside the uterus
• Prevents an early expulsion of the fetus

Question 4

around the time of birth there’s this dramatic droop in what hormone

Answer 4

• progesterone

- If drop doesn’t happen, then the female can’t give birth

Question 5

estradiol

Answer 5

-very high during time of birth

Question 6

The hormonal changes that take place right before birth are the most critical to induce ______ and high levels of _____

Answer 6

caregiving behaviors; high levels of motivation

Question 7

In human moms the estradiol to progesterone ratio correlates with ______________ at 3 months

Answer 7

mother-infants attachment

Question 8

prolactin and placental lactogens

Answer 8

high at the time of birth

Question 9

oxytocin is both a _____ and a _____

Answer 9

hormone; neurotransmitter

Question 10

What determines whether something is a hormone or neurotransmitter?

Answer 10

The distance btw where is released and where it acts

Question 11

oxytocin role as a hormone

Answer 11

• oxytocin released into the blood is critical for labor
• Oxytocin is regulating the contractions necessary for labor and the milk reflex necessary for lactation
• Progesterone being really high actively antagonizes oxytocin preventing labor

Question 12

progesterone falls —> oxytocin rises = ?

Answer 12

labor

Question 13

oxytocin as a hormone pathway

Answer 13

• Progesterone being really high actively antagonizes oxytocin preventing labor
• Neurosecretory cells (located in the hypothalamus) —-> send this long axons that synapse on the capillary bed —> get oxytocin which is synthesize in the hypothalamus (two main areas: supraoptic nucleus & paraventricular nucleus )
• Oxytocin is synthesized here and can act on the uterus or can act on the milk congestion reflex during lactation

○ Oxytocin can’t affect infant-mother bonding through this mechanism b/c oxytocin doesn’t cross the blood brain barrier

But that’s not the oxytocin that’s playing a role in maternal behavior

Question 14

oxytocin role as a neurotransmitter

Answer 14

• Oxytocin is also released as a neurotransmitter at synapses directly in the brain
• Plays a role in the onset of maternal behavior

-there is a lot of oxytocin released in central regions of the brains
Impairment of oxytocin in these regions can interfere with the onset of maternal behavior and infant-mother bonding acting in the brain

Question 15

interference with oxytocin activity (lesion the primary area of the brain where oxytocin is synthesized = paraventricular nucleus of thee hypothalamus ) disrupts what ?

Answer 15

• the onset of maternal behavior
• f we inject an antagonist drug into the regions where we see oxytocin being upregulated or increased at the time of birth you can interfere with the onset of maternal behavior

Question 16

intracerebroventricular injections (into the brain) stimulate what ?

Answer 16

• maternal behaviors in the presence of estradiol
• If oxytocin is injected into the brains of animals who haven’t experienced birth you can increase maternal behavior (promote it)
• High Licking and grooming is correlated with higher expression of oxytocin in the brain

Question 17

natural variation in mothering behavior is correlated with what ?

Answer 17

• the distribution of oxytocin receptors in the MPOA at birth
• Distribution of oxytocin receptors in the MPOA at birth is correlated with motivation to interact with infants

Question 18

there is large evidence relating oxytocin and ________

Answer 18

maternal behavior / care

Question 19

where is oxytocin coming from?

Answer 19

• One of the main regulators of oxytocin receptor expression is estradiol
• Estradiol is a steroid hormone
• Is released in the periphery and can go all over the place and get into the brain easily
• One of the main ways it produces effects is by binding to receptors and functioning as a transcription factor
  
  • Is the ligand-receptor complex that becomes the transcription factor
  • One of the genes that gets turn on is oxytocin receptor

Question 20

medial preoptic area (MPOA)

Answer 20

• this region is critical for maternal behavior

- Disruption in this region will cause mothers to not care for infants ever again

Question 21

other behavioral responses types besides caring

Answer 21

• There are neural circuits that regulate attack and ignore
• these circuits actively antagonist caregiving circuits
• If a mother has damage to the brain that is involved in caregiving behavior the results could be killing their offspring

Question 22

The stimulus that seems to drive ignore or attack behavior ?

Answer 22

the odor of the infants

Question 23

periaqueductal gray

Answer 23

• general aversion system

- region involved in ignore and attacking

Question 24

The stimulus that seems to drive caregiving ?

Answer 24

• vocalization and physical cues
• Vocalizations/ physical cues —> ventral tegmental area (area involved with rewards) releases dopamine into—> nucleus accumbens (dopamine released here is correlated with how motivated an animal is to interact with their infants)

Question 25

damage to what area can lead to infanticide (killing of offspring )

Answer 25

medial peptic area (MPOA)

Question 26

T or F: mother rats show natural variation in licking and nursing behaviors

Answer 26

true -this naturally occurring variations a useful model with which to explore experience effects on the development of maternal care

Question 27

variation in maternal care affects offspring stress responsitivity in adulthood how ? -If rat is reared in a low LG environment then their BEHAVIORAL response to stress is ?

Answer 27

- behavioral inhibition - reduced exploration of novel environment - Enhanced novelty induced suppression of feeding - Being reared in a low LG environment enhances the fear of novel situations -increased vulnerability for stress-induced learned helplessness

Question 28

variation in maternal care affects offspring stress responsitivity in adulthood how ? -If rat is reared in a low LG environment then their PHYSIOLOGICAL response to stress is ?

Answer 28

- increased ACTH - increased corticosterone - increased corticotropin releasing factor - reduced hippocampal glucocorticoid receptor expression (gene and protein ) -All the the segments of the axis are enhanced and the ability to shut down the axis is reduced b/c there are fewer glucocorticoid receptors in the hippocampus

Question 29

How does this experience of early life licking and grooming end up impacting something like the glucocorticoid receptor long term ?

Answer 29

-Experiences of LG are occurring when offspring are pups HOWEVER the behavioral responses and the physiological responses are occurring when the offspring are adults

Question 30

The changes are initiated as mom is licking and the changes are regulated through signaling pathways. How?

Answer 30

Environmental stimuli induce changes at the level of the chromatin very often through activation of the intracellular signaling cascades which ultimately regulates how transcription factors can bind to regulatory elements to drive gene expression

Question 31

5HT agonists increase ______ expression, and this effect is correlated with _____ formation

Answer 31

GR; cAMP

Question 32

5HT7 receptor ______ block the ____ induced increase in GR expression

Answer 32

antagonists; 5HT

Question 33

____________ block the 5HT-induced increase in GR expression

Answer 33

protein kinase A inhibitors