Affiliative and Reproductive behaviour Flashcards
Reproduction and affiliative behaviour meaning
reproduction- activity animals do to produce more of them. mate → exchange dna info in order to produce offspring
Display different behaviours, attract attention of other sex to try increase the chances of mating.
affiliative behaviour- relationship with other animals that are not intended to reproduce the species (shaking hands, birds flying together)
social interactions are classified as affiliative behaviours
The experimental wedding
Explain the study
- Linda and Nic, both science writers.
- Studied their ‘love hormones’ during their wedding in Devon (see how these hormones are affected by this experience)
- Blood taken before and after ceremony
- Measured oxytocin, vasopressin, cortisol, and testosterone, before and after the ceremony.
The experimental wedding
Results
- Oxytocin (the ‘love hormone’) levels were up.
— Bride Linda has the highest change- much more oxytocin immediately after the ceremony compared to before.
— Then mother, father and groom had the highest changes - Vassopressin (the “possession hormone”) went down in Nic. (they argued maybe because he was already married to Linda he didn’t feel possession anymore)
- Cortisol (the ”stress hormone”) was up in Linda before and even higher after the wedding, whereas in Nic cortisol levels went down after the ceremony.
- Testosterone (hormone related to sexual behaviour in males) levels doubled in Nic.
Castration and hormone replacement: Arnold Berthold
Study and results
- Looking at the maturation of chickens into roosters
- Looking at castration in these animals- removing testis and see what was the effect on development
Findings:
Group 1: when animal is castrated, development is altered so the animals don’t develop these characteristics (long tail and neck) of the rooster
Group 2: castration and reimplantation of testis- this animal developed normally
Group 3: castration and transplantation of testis (removed testis in chicken 1 and implanted in chicken 2 that was already castrated). Testis transplantation restores normal development in roosters. Transplanted testis were not connected to blood supply or neuronal networks.
Their effect was mediate by chemicals released to the blood stream:
HORMONES!!
What are hormones:
- definition of hormone
- definition of neurohormone
- definition of target
Hormone: signalling molecular that can carry messages to distant targets through the blood stream (eg testosterone)
Neurohormone: an hormone released by neurons. Targets neighbouring or distant cells (eg. oxytocin)
Target: organs/cells that can detect hormone/s and it is affected by it/them.
What did Dr John Brinkley investigate in relation to testis transplant in humans with “weak sexuality”
Someone was suffering from weak sexuality and they received implant from the testis of goats (in the belly)
The sexual activity of these people became better
Brinkley’s surgeries were a success for some time, but ethical, methodological, and safety aspects made this enterprise unsustainable → which lead to it being stopped
Note: Viagra, introduced in 1998, produced $1B sales that year, highlighting the market for sexual enhancers.
What are the hormone classes
Steroid hormones: derived from cholesterol, they can easily travel across cell membranes. e.g., cortisol and progesterone.
Amine hormones: derived from the amino acid tyrosine. Cannot easily cross the cell membrane, so the receptor for this hormone has to be outside expressing in the membrane of the cells. e.g., thyroid hormone (TH). (so the receptor for this hormone has to be outside)
Peptide and protein hormones: amino acid chains (short chain= peptide, long chain= protein hormone). Cannot travel through cell membrane = activate membrane receptors. E.g., oxytocin, vasopressin (peptides), prolactin, insulin (protein).
Where are hormones produced?
Sex hormones → female (overies) Estrogen Progesterone, male (testes) Testosterone
Non sex hormones (both in females and males) →
- Growth hormone (GH) from pituitary gland (in brain)
- Thyroxine (TH) from thyroid gland
- Insulin from pancreas
- Adrenaline (ADH) from adrenal gland
Genetic sex and meiosis
Defined by the combination of chromosomes we receive from our parents
Offspring genetic sex depends on the sex chromosome carried by the sperm and egg
(ovum) that generates them.
Meiosis- splitting in half the chromosomal content of the cells of these people. Each one of the cells produced by meiosis has half the content of chromosomes. When these combine together and over with the sperm of the other male, they can produce different individuals of different sex
- X copy of chromosome from mother and X from father → they will become genetic females
- X copy of chromosome from mother and Y from father → they will become genetic males
- So…Genetic sex depends on the father sperm cells, which carry X or Y sex chromosomes.
Development of sex organs:
1- info present?
2- what is exposure to sex hormones responsible for
3- what does the Y chromosome control?
4- list sex hormones
1- All the information to develop bodies of either sex is present in the 22 nonsex and the X chromosomes.
2- Exposure to sex hormones, both before and after birth, is responsible for sexual dimorphism.
3- The Y chromosome controls the development of the glands that produce the male sex hormones (testosterone).
4- Sex organs: gonads (ovaries and testes), internal sex organs, and external genitalia.
Gonads:
- what are they in terms of development
- ______ gene expresses _______ protein which differentiates ______ into _______
- lack of _____ results in ______
Gonads (testes or ovaries) are the first to develop: produce ova or sperm, and hormones.
Sex-determining region Y (SRY) gene (from Y chromosome) express SRY protein that differentiates gonads into testes.
Lack of SRY results in ovaries development (become female version)
Internal sex organs:
- what happens at 2 months of gestation?
- what happens at month 3?
- what do female internal organs not need?
- During the first two months of gestation, fetus can develop into either male or female.
- At month three, if testes are present and producing hormones (anti-Müllerian hormone and androgens), the internal sex organs develop into male ones.
- Female internal organs do not need the presence of any other hormone to develop.
2 hormones linked to internal sex organs
anti-müllerian:
- Precursor of female internal sex organs is called the Müllerian system
- This hormone that is produced by the testicles will stop that system from developing- will stop that organ from becoming ovaries
Androgens also influence the development of the testicles
External genitalia:
- what do they not need to develop into female organs
- what develops external genitalia into male version?
- As with internal sex organs, external genitalia do not need hormonal influence to develop into female organs.
- Dihydrotestosterone (androgen produce by testes) develops external genitalia into male version
Sexual maturation:
1- what characteristics are concerned with this section + development and influence
2- what does the hypothalamus release and implication
3- what do testes and ovaries release
4- what are responsible for development of secondary sexual characteristics in males and females?
1- Secondary sex characteristics develop during puberty and are influenced by hormones. (Addams apple, facial/ pubic hair, wide hips in females)
2- The hypothalamus release gonadotropin-releasing hormone (GnRH), which ultimately stimulates hormone release by testes or ovaries.
3-
- Testes release testosterone (androgen)
- Ovaries release estradiol (estrogen)
4- Gonadotrophins (testosterone and estradiol) are responsible for development of secondary sexual characteristics in males and females, respectively.
Hormonal control of sexual behaviour:
1- what do hormones do?
2- example
3- sexual behaviour in non-primates / primates
1- Hormones not only control sexual development, but also interact directly with the nervous system to affect sexual behaviour.
2- E.g., hormones control the female reproductive cycle: the menstrual cycle (estrous cycle in non-primate mammals)
3-
- In non-primate females, sexual behaviour is linked to ovulation (sexual behaviour is only present when the female receptive- it can be fertilised)
- Primate females mate at any time during their menstrual cycle.
Hormonal cycle
What we know is that there are different hormones produced by different sections of the body and that these hormones will produce the cycle. Eg. the FSH is produced by the pituitary gland in the brain and that will trigger the production of estradiol which will peak in the ovaries. And this chemical that is released by the ovaries in females will impact the pituitary organ and it will release luteinising hormone. This is the ovulation part of the cycle, once the ovas is away from this follicule, then the corpus lutem is not producing estradiol and progesterone (the 2 female hormones). And this will effect the uterus in preparation for that egg if it is fertilised and is eventually implanting individuals.
sum:
FSH → estradiol → LH → ovulation → estradiol + progesterone (from corpus luteum)
Hormones and sexual behaviour in male rodents:
1- list 3 stages of male rodents sexual behaviour
2- depends on?
3- what happens when animals are castrated?
4- what happens when animals are injected with testosterone?
1- mounts, intromission, and ejaculation
2- Depends on testosterone levels: castrated male rats injected with testosterone reinstate sexual behaviour.
3- When animals are castrated, that behaviour goes down. The testicles are not producing these hormones anymore
4- If animals are injected with testosterone, the behaviour goes back- just the injection of testosterone in the bloodstream makes the animal behave again sexually.
What is sexual behaviour in female rodents called?
Lordosis
Hormones and sexual behaviour in female rodents:
1- what does the female initiate and what happens when receptive
2- what does sexual behaviour depend on? What do ovariectomised rats display?
3- what does ER and ER -/- stand for?
4- what happens for ER and ER -/- animals?
5- similar effects with?
1- The female initiates copulation. When receptive, it will approach the male.
2- Sexual behaviour depends on estradiol and progesterone. Ovariectomised rats (ovaries removed) display no sexual behaviour.
3- ER: estradiol receptor. ER -/-: ER knockout rats
4- Females with no ER have no receptivity for males. The knockout animals do allow for some mounts to take place but there is no intermission. This is because there is no signalling through this estradiol received in different parts of the brain because the receptor is not there.
5- Similar effects with progesterone receptor KO females (Lydon et al., 1995).
Neural control of sexual behaviour: tools
- Retro-tracing to define the circuit that control sexual organs (e.g., Marson & Murphy, 2006). Injection of pseudorabies virus (retrograde tracing) in sexual organs (penis, vagina, clitoris). They can trace up to the brain where the neurons that control the sexual organs are located.
- Activation of Fos, a marker of neuronal activity, in key brain regions.
- Identify of neurons containing sex hormone receptors: estrogen and progesterone or testosterone.
