Lecture 12 Sexual Behaviors

Organizational

Steroid hormone promotes a particular developmental pattern or ensemble of changes but only during a certain window of development

Activational

Steroid hormone transiently is able to alter behavioral and physiological measures

What did Berthold's experiment find?

The testes release testosterone which plays an important role in male behavioral and physiological development.

Activational effect example

Increases or decreases in testosterone do not alter or dramatically reorganize physical characteristics but can affect behavior

Organizational effect example

Removing but reimplanting the testes elsewhere in the body will promote the develop of male features and behaviors

What does the Sex Determining Region (SRY) promote?

The development of the testes which produce testosterone

Sex Determining Region (SRY)

Contained on the Y chromosome, determines the sex by chromosomal identity

DHT

External sex organ development is regulated by this steroid such as the penis

Aromatase

Enzyme expressed in neurons in the brain, and highly expressed in the hypothalamus

Aromatization

Aromatase converts testosterone into estradiol

The aromatization hypothesis

During development testosterone is high, it enters the rodents brain and is converted to estradiol which acts to masculinize the developing nervous system

What is the SDN-POA?

Involved in the production of male sexual behavior. The male is 3-5x larger than female rats.

What happens if you inject female rats with testosterone or estradiol right after birth?

Causes their SDN-POA to become as large as a typical male

What happens if castration or hormone receptors are blocked in male finches?

Neither prevent nuclei from developing a masculine phenotype in genetic males

Where does the male hormone come from in finches?

The male genotype produces steroid hormones, independent of gonads

Gonadromorph

Each half of the body has a different sex chromosome compliment, half female chromosomes and half male

Gonadal effects (4)

Sex behavior, LH secretion, aggression, nociception

Sex chromosome effects (4)

Habit formation, alcohol preference, aggression, nociception

In response to ovarian hormones what happens in the hippocampus?

Neurons in the CA1 subregion exhibit rapid and reversible changes in synaptogenesis.

By increasing the expression of vasopressin V1A receptor in the ventral pallidum does what to promiscuous male voles?

It pair bonds

In a male prairie vole, what happens when you block the V1A receptor in the ventral pallidum?

It prevents pair bonding

In female voles more time spent being an active parent was directly linked to what?

The more oxytocin in the nucleus accumbens

If you block oxytocin receptors in the nucleus accumbens of a female pairie vole what happens?

It prevents pair bonding

If amphetamine is introduced to pair-bonded and naive voles what happens to each group?

Pair bonded prairie voles don't show a preference but naive voles do.

If a prairie vole experiences a stressful event and the oxytocin receptor signals are blocked what happens?

The vole does not directly consol or groom the mate

What is the expression of the vasopressin V1A receptor in male meadow voles?

Low expression

What is the expression of the vasopressin V1A receptor in male prairie voles?

High expression