Lecture 9 - Reading Flashcards
Stress hormone affects on fetus
Hypothesis by Nathanielsz
Stress hormones impacting a fetus can directly alter stress responses later in life
Hypothesis by Nathanielsz: set-points in the HPA axis would have been altered by neonatal stress hormone elevation altering the animal’s stress responses even throughout adulthood
Early exposure to glucocorticoids contributes to temperament and affects likelihood of depression and other mood disorders
What happens of you inject test into a newborne female mammal?
2 things
One menstrual and one behavioural
Won’t ovulate
Won’t display female-typical sexual behaviors
If newborn male is deprived of testosterone (castration)
2 things
Increase LH levels following estrogen and progesterone exposure
Will display female-typical sexual behaviors
If testosterobe is injected into a female in the critical period for sexual development (3 things)
Hypothalamus
LH secretion pattern
What type of sex-specific sexual behaviours
Low number of hypothalamic preoptic area spine synapses
Acyclic LH secretion
Low female-typical and high male-typical sexual behaviors
Effects of early sex hormones If test is injected into a female after the critical period (1 thing)
No effect
Critical period in humans vs. rats
Critical period for humans occurs in utero, but for rats it occurs after birth
What happens when you have elevated stress hormones prenatally
HPA axis is sensitive to high maternal glucocorticoid levels
Elevated adrenal hormone levels in the prenatal period → greater stress sensitivity in sympathetic NS, altered learning capacities
Prenatal stress hormone may increase neuronal vulnerability to oxidative stress
Basics of CAH
Congenital adrenal hyperplasia (CAH): genetically based deficiencies in enzymes involved in glucocorticoid synthesis leads to a decrease of steroid precursors into androgenic pathways
Excess in utero testosterone can cause pseudohermaphroditism, abnormal external genitalia development
Androgen insensitivity basics
Androgen insensitivity: have external female genitalia, have testes that secrete testosterone, are sterile
Females (vs. males) are usually (6 things)
1) More interested in parenting
2) Better overall verbal ability
3) Speech production
4) Verbal fluency
5) Math problem solving ability better in childhood
6) Better perceptual speed and accuracy
Males vs. females are usually (6 things)
1) More likely to be left-handed
2) More aggressive
3) More likely to have language left-lateralized in the brain
4) Better at analogies
5) Problem solving ability better in adulthood
6) Better and faster at mental rotation
XY individuals with complete androgen insensitivity have
female phenotypic sex, sex of rearing, and gender identity
So concurence between phenotypic sex and gender
Not definitely genotypic
XX individuals with CAH have
What genitals at birth
Will this be treated?
Often have what sex-typical behaviours
masculinized external genitalia at birth
but it’s usually treated surgically
tend to have more male-typical behaviors
How does stress hormones early in development change things?
What brain regions are altered (2)
How do neurons here tell the rest of the brain what to do?
High levels of stress hormones during early development may cause alterations in the:
lower brainstem
locus ceruleus
Neurons in this region respond strongly to salient stimuli (including stress) and tell the rest of the brain about them through long-ranging adrenergic projections
Prenatal stress hormone injection in rats caused… (4 things)
1) Reduced ACTH production in the periventricular nucleus of hypothalamus
2) Reduced expression of CRF/CRH, the neuropeptide that causes ACTH release
3) Reduced expression of glucocorticoid receptors
4) Reduced vasopressin production
Chronic maternal stress during pregnancy caused…
What does it do to BDNF
reduced gene expression of brain-derived neurotrophic factor (BDNF) in the PF
Postnatal stress caused…
Same, gene expression in BDNF
reduced BDNF expression in hippocampus
Insufficient circulation of thyroid hormones during development →
What does it do to morphology?
What does it do to cognitive ability?
abnormalities in morphological brain development → severe cognitive disability
Subtle changes in thyroxine in pregnant women can…
(in terms of neurological development)
negatively impact their child’s neurological development
Behavioral deficits depend on time of thyroid hormone loss (early and late in pregnancy + after birth)
Early in pregnancy: visual attention and processing problems
Later in pregnancy: decreased visuospatial skills, slower motor responses
After birth: impaired language and memory
Testosterone may act as a pre-hormone in specific areas, converted by…
(what makes it DHT)
5𝛼-reductase to 5𝛼-dihydrotestosterone
In the study with male pseudohermaphrodites, they have (5 things)
1) Ambiguous external genitalia
2) Raised as girls
3) Voice deepens during puberty
4) No breast development
5) Phallus enlarges to become a functional penis
How were test and DHT levels in the subjects
1) Testosterone levels were normal
2) 5𝛼-dihydrotestosterone levels were low
Defect in 5𝛼 reduction results in what?
Do we know why the enzyme is not working?
Decreased conversion of testosterone to dihydrotestosterone
Unknown whether the error is due to synthesis, structure, or metabolism of the enzyme
What hormones are needed during embryogenesis and puberty for complete male external genital development?
During embryogenesis and puberty, both testosterone and dihydrotestosterone are necessary for complete male external differentiation and development
What hormone acts on the Wolffian system
What does it cause to develop
(think what the Wolffian system is)
Testosterone secreted in utero acts on the Wolffian system (development of internal sex organs)
What does testosterone converted to DHT cause to develop?
Testosterone’s conversion to dihydrotestosterone results in differentiation of external genitalia and prostate
What hormone relates to male sex drive?
Male sex drive appears to be related to testosterone only
How is 5𝛼 reductase deficiency inherited
Disorder is genetic, inheritance is autosomal recessive
