HW - Sexual Dimorphism III Flashcards
How can sexual dimorphism in rodent hypothalamus be detected?
Tyrosine Hydroxylase antibody stain for Anteroventral paraventricular nucleus
used for control of cyclic ovulation
- Is larger in females than in males and is responsible for the control of cyclic ovulation
What is the difference between a male and a female spotted hyena?
Spotted hyenas exhibit sexual differentiation, where females are
- Larger
- More aggressive
- Socially dominant
What happens in female spotted hyena fetuses exposed to androgens in the womb (utero)?
Androgen exposure causes some masculinization (larger urogenital opening) but limited feminization (smaller clitoris) in female spotted hyena fetuses. It doesn’t explain all their unique traits
How does blocking androgens in utero affect male spotted hyena fetuses?
Blocking androgens in the womb partially feminizes male spotted hyena fetuses, creating a clitoris-like penis and female-like reproductive structures
What brain region shows sexual dimorphism in the rodent brain?
Sexual dimorphism is shown in the ventromedial hypothalamus (VMH) and medial amygdala (MeA) of a rodent brain
How might sex hormones influence the size and cell number of the AVPV and BNST in rodents?
Sex hormones like estrogen and progesterone, more abundant in females, are likely responsible for the larger size and potentially more Calbindin-positive neurons in the AVPV and BNST observed in females.
Describe the neural connection between the accessory olfactory system, the hypothalamus, and the regulation of reproductive behavior in rodents.
The accessory olfactory system projects to the medial amygdala (MeA) and bed nucleus of the stria terminalis (BNST), which in turn send signals to the ventromedial hypothalamus (VMH).
The MPOA in the hypothalamus contains GnRH neurons that regulate reproduction.
- This neural pathway suggests that pheromones can influence reproductive behaviors.
Which areas of the rodent brain are present in pheromone perception and sexual behaviour?
Pheromone perception:
- MeA
- BNST
Sexual behaviour:
- MPOA
- VMH
How do TRPC2 and CNGA2 proteins influence sex-specific behaviors in rodents?
TRPC2 is required for male-specific courtship behavior and suppressing courtship in other males
- Suggesting a role in social interactions.
CNGA2 is essential for male mating behaviors, territorial aggression, and surprisingly, female maternal pup retrieval.
- This implies both sexes utilize this pathway for different behaviors.
What is the function of aromatase-expressing BNST neurons in male rodents?
These neurons appear to be important for distinguishing between males and females, potentially influencing mating behavior.
- They are more active towards females and activating them with light led to mounting behavior towards another male
How did the researchers demonstrate the role of aromatase+ BNST neurons in sex discrimination in male rodents?
They measured calcium activity in these neurons, which indicates firing, while the male encountered a female, another male, or an inanimate object.
- The neurons were most active around females.
Additionally, activating these neurons with light made males mount another male, a behavior usually seen towards females
What is the effect of stimulating the ventromedial hypothalamus (VMH) on lordosis behavior in female rats?
Stimulating the VMH with electrical current significantly increases lordosis scores, indicating it enhances this mating behavior
- Lordosis posture (arching the back and raising the hindquarters)
What are the effects of ablating progesterone receptor-expressing (PR+) neurons in the VMH on female mice and male mice? (2)
Female mice with ablated (destroyed) PR+ VMH neurons displayed:
- Rejection of courting males
- Lack of lordosis behavior (mating posture)
Male mice with ablated PR+ VMH neurons exhibited:
- Reduced mounting and intromission (sexual behaviors) towards females
- Decreased aggression towards intruder males
How does sexual experience affect the response of Esr1+ VMH neurons in male rodents>
Sexually naive males showed similar activity in these neurons to all intruders (male or female).
- This suggests prior sexual experience might be necessary for Esr1+ VMH neurons to distinguish between the sexes of intruder
How does pup retrieval behavior differ between lactating mothers and naive virgin female mice?
Lactating mothers retrieve pups placed outside the nest much faster than naive virgin females, who typically ignore the pups.
- This suggests hormonal changes and experience play a role in maternal motivation.
