Endocrine Influences Flashcards

1
Q

Outline some differences between NTs and Hormones

A

NT - Effect specific, Digital (All or nothing) effect, Mediate rapid changes, Short distances traveled (across synapse), voluntary control

Hormones - Widespread effects, Anologue (graded) effect, mediate long-term changes, travel long distances (circulatory system), very little voluntary control

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2
Q

What are the four kinds of hormone?

A

Monoamine - catecholamines
Peptide -
Protein - eg. thyroid hormone
Steroid - sex hormones

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3
Q

How do protein and peptides act?

A

Bind cell membrane

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4
Q

How do steroids act?

A

bind mRNA -> changes protein synthesis

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5
Q

Give examples of Monoamine hormones

A

Catecholamines eg. NA, Adr, (may be NT or hormones)

DA - NT

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6
Q

What three levels may hormones act upon?

A

Sensory
CNS
Effector

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7
Q

Give an example of how hormones affect sensory systems

A

Testosterone ^ detection of oestrus in the female

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8
Q

How are hormone levels regulated?

A

Physiological by-products of their activity feed back negatively
Stimulation or inhibition of other hormones (either in regulatory chain or neg/pos feedback)
Conditioned release eg in mice LH surge is conditional upon linking with female mouse (?)

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9
Q

Give an example of negative feedback

A

PTH -> ^ Blood [Ca], [Ca] -> vPTH

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10
Q

Give an example of positive feedback

A

Stress response, Fergusson reflex, LH

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11
Q

Why are biological rhythms in hormone levels seen?

A

To synchronise biological function with environmental changes

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12
Q

What is the name for cycles based upon day length? Night length?

A

Cicadian, Circalunar (for nocturnal species - more active at the full moon)

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13
Q

What are the four main endocrine systems relevant to behavioural problems?

A

Insulin and glucose metabolism
Thyroid hormoens
Steroid hormones - glucocorticoids and mineralocorticoids
Sex hormones

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14
Q

What are the two functions of sex hormones?

A

Direct sexual activity directly

Gender differences - females more anxious, males more impulsive

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15
Q

What does castration prepuberty cause in non primates?

A

Lack of testosterone means will not develop aggressive tendencies

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16
Q

What peripheral endocrine effects do the sex hormones have?

A

Pubertal changes

eg. cheeks in tom cat

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17
Q

How may sex hormones alter CNS activity?

A

Act as modulatory NTs - direct and genomic effect on pathway activation, changing likelihood of response to stimulus

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18
Q

What hormone is affected by oestrogen?

A

ACTH and other stress hormones - change likely to be greater in females
This phenomenon disappears with ovariectomy

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19
Q

Which hormones are involved in aggressive responses?

A

AVP and CRH

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20
Q

What other effects do sex hormones have on the brain? How may neutering affect this?

A

-> neural plasticity and synapse formation

^ risk of cognitive dysfunction and long term learning disabilities

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21
Q

How may sex hormones end up in the brain? What kind of effect are they said to have?

A
Cross BBB
Local synthesis from cholesterol
Conversion in the brain 
eg. testesterone -> oestrogen; progesterone -> pregnanolone (active metabolite) 
- Tonic effect
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22
Q

What are the four stages of oestrus in the bitch?

A

Pro-oestrus, Oestrus (LH spike, will stand), Metoestrus (pregnancy, ~ 7 months), Anoestrus

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23
Q

What occurs pre-season in the bitch? How may this affect behaviour?

A

3 weeks pre-season, ^FSH/LH -> ^E2
Moody, irritable, very attractive to males
When in season bitches may urine mark

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24
Q

What general effect does P4 have on behaviour?

A

Calming

Primes behaviour for when it falls (ie. end of pregnancy it drops-> maternal behaviour)

25
Q

Where are FSH and LH produced?

A

Anterior Pituitary

26
Q

What general effect does Oestrogen have on behaviour?

A

^aggression especially to other bitches

lower threshold for pain and seizures

27
Q

Where is oestrogen produced?

A

Follicles in the ovary

28
Q

What effect does oestrogen have on neurobiology?

A

^Neurogenesis

29
Q

What is the action of pregnanolone?

A

Acts at GABA a receptors - anxiolytic effect

30
Q

What behaviours does PRL initiate?

A

Milk let down, grooming, maternal aggression to protect young, reduces response to stressors in rodents

31
Q

What relation do P4 and PRL have?

A

v P4 -> ^ PRL

32
Q

How may pseudopregnancies be adaptive?

A

Allows for co-operative rearing

33
Q

When are testosterone surges experienced?

A

Pre-natal - causes male to be male (female = default)

Post-natal adolescent - sexual maturity changes

34
Q

At what age do male dogs start to cock leg and show mounting?

A

6-18 months

35
Q

What actions does testosterone have on behaviour and physiology?

A
v frustration tolerance 
^ aggression
leg cocking and mounting 
Anabolic (^metabolism)
Converted to oestrogen in the brain - affects firing of serotinergic neurones
36
Q

Why are testosterone levels not high all the time?

A

High energy cost and decreased immune function - only elevated when necessary according to the ethology of the species, hence why a breeding season may be beneficial

37
Q

How is immunity affected by testosterone?

A

T cells

38
Q

When may testosterone levels be high?

A

After a successful competitive encounter (shown in human sports players and fans)

39
Q

If a bitch is spayed before her first season can she have a pseudopregnancy?

A

NO

40
Q

Why may neutering a male not be effective at dereasing aggression?

A

If it has become a learned response

41
Q

Why may neutering a female not be effective at decreasing aggression?

A

Tonic levels of testosterone may have been masked by female hormones - prevailing testosterone can now cause aggression
Neutering may v self confidence -> ^fear related aggression

42
Q

How is oestrogen modulated?

A

Serotonin pathways

43
Q

What type of breeders are queens?

A

Seasonally poly-oestrus, long day breeders (Spring->Autumn)

Induced ovulators

44
Q

When are pseudopregnancies caused in the queen?

A

Infertile mating or other contact that induces ovulation

45
Q

What is the main action of corticosteroids?

A

^blood glucose

46
Q

How does chronic stress impact the HPA axis?

A

Find out!

47
Q

Outline the HPA axis

A

Hypothalamus - CRH
Anterior Pituitary - ACTH
Adrenal Cortex - Glucocorticoids especially cortisol

48
Q

What are the two pathological states of adrenocorticoid production?

A

Hyperadrenocorticism (Cushings)

Hypoadrenocortocism (Addisons)

49
Q

What are the common causes of Cushings?

A

Cortisol secreted from adrenal cortex tumour

ACTH secreted from an anterior pituitary tumour

50
Q

What is the usual cause of Addisons?

A

Autoimmune - Adrenal cortex detroyed -> v mineralocorticoids and possibly corticosteroids -> poor stress response

51
Q

Which organs does thyroid hormone act upon?

A

ALL

52
Q

What is the function of thyroid hormone?

A

Control metabolic rate

- direct centra l’impact on serotinergic activity

53
Q

What are the two pathological states of thyroid hormones production?

A

Hypothyroidism - common in dogs, -> obesity, depression, lethargy, bilateral symmetrical alopecia, myxoedema, pendulous abdomen, caused by idiopathic autoimmune thyroid damage or thyroiditis
Hyperthyroidism - common in older cats, -> weight loss, nervousness, staring eyes, poor coat, ^HR, aggression

54
Q

What other form of hyperthyroidism is occasionally seen?

A

Depressed form - Secondary heart/kidney issues

55
Q

What hormones are associated with insulin and glucose metabolism?

A

Cortisol and Leptin

56
Q

How may insulin affect behaviour?

A

Cross BBB, affect food seeking behaviour and glucose metabolism

57
Q

What are two pathological states associated with insulin?

A

Diabetes mellitus - vInsulin -> HYPERglycaemic

Insulinoma - ^Insulin -> HYPOglycaemic

58
Q

What behavioural problems may be associated with insulin?

A

Resource guarding and stealing