Presentation on Lecture Slides-05 Hormonal System.pdf

Presentation on hormonal control

1. Animal Behavior


Mechanism of Behavior
Hormonal System & Behavior


Code: Z-4208
BS (Hons) Zoology
Semester V
Animal Behavior Z-4208 Department of Zoology, GC University Lahore

2. •How the hormonal differences result in development of specific structures
for mediating behavior?


•What is the mechanism behind courtship behavior of crabs?


•How hormonal changes induce alterations in perception and sensation of
animals?


•How the frogs communicate during their courtship and reproductive
season?

Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Questions to be discussed

3. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Endocrine System & Behavior
•Midshipman fish (Porichthys notatus) sings to attract a female fish

•Male fish contracts a pair of vocal muscles against swim bladder.

•Nest are located under the rocks of the intertidal zone

•Male may mate 5-6 females in a breeding season

4. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Distinct Mating Strategies of Males
•…

5. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Song to Attract Female
•Type I males: larger, take longer to reach maturity, motor neurons
and brain area for singing is larger, sing to attract female

•Type II males: vocal muscles are less developed, small bodies and
larger gonads, matures earlier, resembles a female

6. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Song to Attract Female

7. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Song to Attract Female
•Type II males lie outside the entrance and deposit their sperms while
fanning water toward the nest’s opening

8. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
The Endocrine Glands & Hormones
•Hormones are secreted either by endocrine glands or neurons
(neurohormones).
•Chemical substances secreted in one part of body and act on other
part of body (usually utilizes blood as transport medium).

•Hormones may have diverse effects within an individual
•It may serve to communicate between individuals of same species

9. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
20-HE (20-hydroxyecdysone)
•Molting hormone in crustaceans
•Y-organs are non-neuronal paired endocrine glands in crustaceans

10. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
20-HE Deters Mate & Predators
•Feeding deterrent between individual shore crabs (Carcinus maenas)
•Prior to female molting, a male will guard her from rival males and
predators by cradling her beneath his abdomen for a few days
•20HE released by the female effectively deters her mate (or octopus) from
eating her

•20HE acting as hormone as well as pheromone

11. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Hormonal Communication
•The endocrine system is closely associated with the
nervous system, sometimes is known as
Neuroendocrine system
•Neurotransmitters produce rapid response, short in
duration, and highly localized and
neurotransmitters are rapidly destroyed.

•Hormones are released slowly, remain in
bloodstream for some time, contact virtually all
cells of the body and bind / interact with only those
cells having receptors for hormone binding,
produce relatively long lasting effects
•May turn on certain genes
•Alter cell’s secretory activity
•Change membrane properties

12. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Hormone Types and Mechanism of Action
Peptide hormones:
•3-300 amino acids (Luteinizing & Follicle-
stimulating hormones from anterior
pituitary)

•Water soluble and bind on the surface
receptors of the target cells

•Includes use of a secondary messenger
(such as cAMP )

•Induce short term changes in membrane
properties and long-term changes in
protein function

13. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Steroid hormones:
•Released from gonads and adrenal glands, 4-classes Progesterone,
Androgens, Estrogens (sex steroids), Corticosteroids
•All steroid hormones are derived from Cholesterol & are fat soluble
Hormone Types and Mechanism of Action
•Enters the cell
•Bind with
receptor
•Enters into the
nucleus
•Attaches to DNA
•Gene expression
& protein
synthesis

14. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Steroid-based Hormone Facts
•Hormone output is not rigidly determined by sex, females generally have
small amounts of “male hormones” e.g., testosterone
•Although different hormones produce different effects, sex steroids are
very much similar in structure & may be an intermediate step in the
synthesis of another hormone

15. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Genomic effects:
•Steroid hormone binding to receptor and entering into nucleus for the
gene expression and protein synthesis over several hours to days.

Nongenomic effects
•Steroid effects that occur rapidly after steroid applications, and probably
do not involve modifications to gene expression and protein synthesis
•Steroids acting on the brain through diverse pathways that include interacting with membrane receptors and altering cell-signaling pathways
producing rapid behavioral responses are nongenomic
•https://www.ncbi.nlm.nih.gov/books/NBK28103/

•Neurosteroids produced by the nervous system may act on the same
neuron, or adjacent neurons
•May bind on receptors
•Act on microtubules
Steroid-based Hormone Facts

16. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Hormones Influence Behavior
•Sensory & Perceptual mechanisms

•Development or activity of the CNS

•Muscles involved in performing behavior

?

17. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Influence on Sensation & Perception
•Mate choice partially based on hormone- mediated differences in the
ability to detect stimuli

•
Sus scrofa females detect lower quantities of the boar pheromone 16-
androsterone

•Detection of 16-androsterone leads females to sexually receptive posture

•Males normally do not respond to 16-androsterone, however if male is
castrated (gonads removed) before the age of 5 months and given
estradiol, it will respond to 16-androsterone

18. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
•Vasotocin hormone (in roughskin newts) is similar to mammalian
vasopressin hormone
•The roughskin newts (Taricha granulosa) react to visual, chemical and
tactile stimuli from females
•The mate selection involves visual cues at first (size, shape, color) and
then olfactory cues for confirmation of species, gender and reproductive
state.
•
Male clasps the gravid female for several hours and such a posture is
known as amplexus
Influence on Sensation & Perception
•Vasotocin influences the early
stages of mate choice
•Males injected with vasotocin
spend more time near females, and
show enhanced responsiveness to
tactile stimuli from females

19. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
•Young animals spend more and more time near siblings and family
members

•As young matures, its preference switches to non-family members,
especially of opposite sex.

•Shifts in levels of Androgens, Estrogens and Progesterones are involved in
this behavioral change
Influence on Sensation & Perception

20. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Preference shifts in Microtus pennsylvanicus

•Female meadow voles nest with other females in winters and prefer
female odors than to male odors

•While a female defending its territory, it prefer the scent of a male rather
of a female

•The reversal is caused by the changes in the amount of estrogen produced
inside the female

•Estrogen levels fluctuate in response to seasonal variations (day-length)
Influence on Sensation & Perception

21. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Influence on Development & Activity of CNS
•Several changes may be noted, such as

•Volume of the brain
•Number of cells in brain
•Size of neuronal cell bodies
•Extent of dendritic branching of neurons
•Relative percentage of neurons responsive to particular hormone
•Survival of neurons

22. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Singing behavior in Zebra Finch (males sing)
•In Taeniopygia guttata, at the time of hatching the sex differences
establish the differences in brain nuclei

•
Early exposure of steroid hormone changes the brain characteristics such
as number of neurons in singing associated brain areas and size & number
of androgen receptors

•Later research revealed that neurosteroids rather than other hormones
are involved in such differential development of brain areas in males and
females at an earlier life-stages.
Influence on Development & Activity of CNS

23. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Influence on Muscles
•Consider two examples to illustrate the influence of hormones on muscle
and motor neurons to execute functions

•Calling behavior in frogs

•Copulatory movements in rodents (Self reading)

24. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Calling Behavior in Frogs
•African clawed frog Xenopus laevis inhabits shallow and murky water
bodies

•Male frogs elicit 6-types of calls most of which are advertisement calls,
characterized by metallic-sounding call with alternating fast and slow trills
(trill: a vibratory sound). Fast trills may involve a progressive increase in
volume

•Female frogs responsive to advertisement calls approach males with
rapping calls, involves a shorter interval between clicks
•Non-responsive females release the tick
calls, slow and monotonous clicks with no
change in intensity

25. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Amplectant: Males when clasp female,
release such calls
Growling: Clasped male release growling call
Chirping: Call by male to suppress other male
Calling Behavior in Frogs

26. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
How male frogs vocalize so fast?

•
The characteristics of muscles and neuromuscular junctions of the
larynx are responsible for sex differences in the rate at which calls
are produced

•Male larynx muscles contract and relax 71 times per second
•Female larynx muscles contract and relax only 6 times per second

Calling Behavior in Frogs

27. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Anatomical specialities / differences?

•Adult males have 8 times greater muscle fibers in larynx than do
females

•Male muscles are of fast-twitch, fatigue resistant
•Female muscles are slow-twitch and fatigue-prone

Calling Behavior in Frogs

28. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
•Hormonal influence on vocal muscles?

•Following metamorphosis, the numbers of muscle fibers in young
male and female frogs is similar to that of the adult female.
However, androgen levels rise in male frogs and transform the
number and type of muscle fibers in the larynx.

•Prolactin and thyroid secretions are believed to influence the
masculinization (induce male physiological characteristics) of the
larynx
Calling Behavior in Frogs

29. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Methods to Study Hormone & Behavior

How hormones influence on animal activities ?



Discuss the approaches / strategies to study animal behavior?



Discuss the approaches / strategies to study effect of hormones on
animal behavior?

30. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Methods to Study Hormone & Behavior

1. Interventional Studies
•The behavior changes are monitored after removing the
source of hormone (Source removal, receptor blockage or
removal)
•The reversal of behavioral changes following administration of
hormone or installing a source of hormone prove the
hormonal influence on behavior


2. Correlational Studies
•Changes in behavior in relation to fluctuations in the levels of
hormones in the body

31. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Interventional Studies
Aggressive and Courtship Behaviors of Green Anole

•Green anole (Anolis carolinensis) is iguanid lizard of Southeastern
US
•Male anole defends its territory fiercely to prevent the intrusion of
rival
•Territory often includes the home range of 2-3 females

32. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Interventional Studies
Aggressive and Courtship Behaviors of Green Anole

•Agonistic and courtship displays of male anole includes Bobbing
movements such as
•Extension of red throat fan / dewlap
•Compression of body and lateral display
•Lowering of hyoid apparatus
•Bobbing act (Move up and down)

33. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Interventional Studies
Aggressive and Courtship Behaviors of Green Anole

•
If intruder node its head (submissive posture) at this point,
the aggressive behavior ends, otherwise
•A crest is acquired at the back
•A black spot appears behind the eye
•Fight results
•Courtship behavior is similar, except body is not compressed and
bobbing movements are less stereotyped.

34. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Interventional Studies
Observe followings in
a & b
•Dewlap
•Compressed body
•Crest on back
•Blackspot behind
eye
•Rivals prior to fight

•Courtship ritual of
male (b)

35. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Removing the gonads & Androgen Replacement Therapy

Effect on Courtship behavior:
•A sharp decline in pre-mating behavior following castration in
male
•Exogenous androgen supplies restored the courtship behavior
•Androgens regulate the courtship and copulation in male
green anole
Interventional Studies

36. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Removing the gonads & Androgen Replacement Therapy

Effects on Aggressive behavior:
•Castrated male returned to its territory, it displayed the
aggressive behavior
•Castrated male returned to a new habitat failed to display the
aggressiveness
•Aggressive behavior is partially regulated by the androgens /
gonadal hormones

Interventional Studies

37. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Advances in Interventional Studies
•Cannulation Technique to administer the hormones into specific targets,
such as specific brain regions

•Radio-labelled hormones to track the path of hormones and associated
targets

•Antihormones, that bind reversibly to hormones or receptors and used to
study hormonal effects on animal behavior

•Genetic knockout (KO) animal models, to manipulate the levels of
hormones & its influence on animal behavior

38. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Progesterone Receptor Knockout (PRKO) Mice to Study Feticidal Behavior of
Mice
•Male mice kill the infants, a behavior known as feticidal behavior
•A specific gene (Progesterone receptor) is targeted and inactivated to
eliminate the product
•PRKO mice do not respond to progesterone as the target protein is absent
•PRKO mice do not kill the infants unlike normal male mice

•Normal mice injected with anti-hormone RU486 blocked the progesterone
receptors and rarely attacked the infants

•Mice injected with progesterone implants (a small reservoir of
progesterone) displayed escalated levels of attacks on infants

•Progesterone affects behavior in male
•Different hormones mediate aggression in male mice (in addition to
testosterone)
Interventional Studies

39. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Progesterone Mediated Feticidal Behavior of Male Mice
Interventional Studies

40. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Correlational Studies
•Influence of fluctuations in hormone levels on animal behavior
•Wingfield and Moore (1987) studied behavioral endocrinology of song
sparrows, Melospiza melodia under natural habitat
•Blood samples from wing vein of captured male song sparrows were taken
and birds were labelled with tags on legs
•The blood samples were taken 5-10 times in a breeding season and were
analyzed for testosterone levels
•Behavioral studies were also conducted at the same time
Single breeding Season
Blood samples retrieval
Testosterone level estimation

41. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Correlational Studies
•Close correlation between the levels of testosterone & Aggressive
behavior of male song-sparrow
•Peak levels when female is ready for egg laying
•Testosterone mediates aggressive behavior in males during
breeding season
13-15 days
incubation time

42. Animal Behavior Z-4208 Department of Zoology, GC University Lahore

Challenge Hypothesis:
•Wingfield, 1990
•The levels of hormones that regulate aggression and dominance
are influenced by the social environment.
•More the challenging situation or social instability, potentiated
levels of hormones (such as testosterone) will be observed

•Challenge hypothesis is being tested in other animals and insects
as well.

Correlational Studies

43. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Aggression in non-migratory male song sparrows:

•The males of non-migratory populations show aggression in non-
breeding season as well (following the late summer molt)
•However, diminished testosterone levels are observed in such non-
migratory males.

•Estradiol seems to regulate the aggression in such males

•In male birds dehydroepiandrosterone (DHEA), precursor of
estradiol, seems to be converted into estradiol in the brain tissue
and induces aggressive and territorial behaviors

Correlational Studies

44. Animal Behavior Z-4208 Department of Zoology, GC University Lahore

•Why two different hormones regulate territorial behaviors in
same male in different seasons?

•Maintaining high testosterone levels is a costly process, as it
increases the metabolic rate and decreases body mass, fat storage
and immune functions
Correlational Studies

45. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Organizational & Activational Effects
Organizational Effects:
•Hormones organize neural pathways important for certain pattern
of behavior
•Occur early in life, before or just after the birth and effects are
permanent such as responsiveness of neurons to steroid hormones

Activational Effects:
•Such effects occur in adulthood and transiently persist as far as the
higher concentrations of hormones are secreted.

46. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Sex differentiation in the behavior of Norway rats:

•The copulatory behaviors of rats involve
•Mounting by Male
•Lordosis posture / receptive posture by Female

•The copulatory behavior in rats are due to differences in the brains of
male and female rats

•The masculine or feminine brain development is irreversible and under
the control of androgens in late fetal or early neonatal life.
Organizational & Activational Effects

47. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Sex differentiation in the behavior of Norway rats:
Organizational & Activational Effects
•During perinatal life, male and female rats have the potential to develop
neural control mechanisms for both masculine and feminine sexual
behavior. Certain neurons in the brains of both males and females have
the capacity to bind sex hormones.

48. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Sex differentiation in the behavior of Norway rats:
Organizational & Activational Effects
•The neonatal testosterone causes males to,
•Develop the capacity to express masculine sexual behavior
•Lost the capacity to express feminine copulatory behavior.

49. Animal Behavior Z-4208 Department of Zoology, GC University Lahore
Next ….


•Development of Behavior