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



hormones important for rat gestation

-placental lactogens



-Increases across gestation

-Important for development of the fetus and keeping the fetus inside the uterus

-Prevents an early expulsion of the fetus


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


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



-very high during time of birth


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

caregiving behaviors; high levels of motivation


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

mother-infants attachment


prolactin and placental lactogens

high at the time of birth


oxytocin is both a _____ and a _____

hormone; neurotransmitter


What determines whether something is a hormone or neurotransmitter?

The distance btw where is released and where it acts


oxytocin role as a hormone

- 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


progesterone falls ---> oxytocin rises = ?



oxytocin as a hormone pathway

-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


oxytocin role as a neurotransmitter

- 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


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

-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


intracerebroventricular injections (into the brain) stimulate what ?

-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


natural variation in mothering behavior is correlated with what ?

-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


there is large evidence relating oxytocin and ________

maternal behavior / care


where is oxytocin coming from?

-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


medial preoptic area (MPOA)

-this region is critical for maternal behavior

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


other behavioral responses types besides caring

-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


The stimulus that seems to drive ignore or attack behavior ?

the odor of the infants


periaqueductal gray

-general aversion system

-region involved in ignore and attacking


The stimulus that seems to drive caregiving ?

- 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)


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

medial peptic area (MPOA)


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


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


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 ?

-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


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 ?

-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


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

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


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

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