Jess - Hormone Monster

What is the primary objective of the study regarding gonadal steroid hormones?

To investigate how gonadal steroid hormones affect perineuronal net (PNN) development in the medial prefrontal cortex (mPFC) of male and female mice.

What age groups (3) were examined for their sensitivity to hormone exposure in relation to PNNs?

1. Juvenile (PD 23)

2. Adolescent (PD 40)

3. Adult (PD 63)

Generally, how does age affect PNN density according to the study?

PNN density increases from juvenile to adolescent to adult.

What is the significance of the medial prefrontal cortex (mPFC) during adolescence?

It undergoes significant development during adolescence, affecting emotional regulation and decision-making.

What hormone treatments were used in the study for male and female mice?

17β-estradiol for females and testosterone for males.

In the PL/A32 region, how does PNN density in females change with age?

PNN density increases from juvenile to adolescent/adult, with juvenile estradiol treatment resulting in decreased density.

What trends were observed in PNN density for males in the PL/A32 region?

Juvenile males had lower PNN density than adolescents and adults, with testosterone treatment leading to higher density.

What were the findings regarding hormone effects on PNN density in the IL/A25 region for females?

There were no significant effects of age or hormone treatment in females; sham females displayed a gradual increase in PNN density.

What does the discussion suggest about sensitive periods for PNN development?

There are sensitive periods influenced by hormone timing, with females being sensitive during the juvenile phase and males during adulthood.

What relationship does the study suggest exists between PNNs and synaptic pruning?

A decrease in PNNs in juvenile females may relate to an increase in synaptic pruning occurring in early adolescence.

Adolescence

A key developmental period where brain and behavioral changes coincide with pubertal onset and the secretion of gonadal steroid hormones.

Neuroplasticity

The brain's ability to reorganize neural circuitry, create new memories, learn, etc.

Perineuronal Nets (PNNs)

An extracellular matrix structure that develops around inhibitory parvalbumin (PV) interneurons, stabilizing a PV cell’s synaptic connections and protecting its structural integrity.

PL/A32: Homologous structure/name, location, and function

• Rodent Prelimbic area / Primate Broadmann’s Area (BA) 32

• Located in the anterior cingulate cortex

• balances emotion and reason, maintaining emotional equilibrium by facilitating communication between cognitive and emotional brain regions

IL/A25: Homologous structure/name, location, and function

• Rodent infralimbic cortex / Brodmann’s Area 25 in primates

• Located in the subgenual cingulate cortex (ventromedial prefrontal cortex)

• implicated in the regulation of autonomic and endocrine functions and maybe processing emotional information

How were hormones delivered to rats?

Silastic capsules were implanted between the shoulder blades to administer gonadal sex hormones for one week

What is the Sensitive Period for Visual Perception?

A period in the first few months of life where visual stimuli is required for the normative development of the visual cortex

What is the relevance of Estrogen Receptor beta (ER-ß)?

Activation of these receptors may be one of the mechanisms of how gonadal steroid hormones affect PNNs.

Why does this study investigate PNN development?

Disruption or variation in PNN development is linked to mental health disorders (e.g., schizophrenia, bipolar disorder).

What do PNNs mark, and what do they do?

• PNNs increase during adolescence

• May signal the closure of sensitive periods in brain development.

• Net development crystallizes learning & neural circuits

Why does the study investigate PNN development in the mPFC before/during/after puberty?

• PNNs increase during adolescence.

• Abnormalities in pubertal timing increase the risk of developing a mental health disorder

• The mPFC undergoes significant development during adolescence and contributes to changes in emotional regulation and decision making.

Describe the study design/variables.

• Sex (male, female)

• Age (juvenile, adolescent, adult)

• Treatment (GDX + blank, GDX + T/E)

• sham = baseline comparison

When were brains collected?

• Brains collected 1 week after silastic capsule implantation

• Juvenile PD 30

• Adolescent PD 47

• Adult PD 70