Endocrine Influences Flashcards
Outline some differences between NTs and Hormones
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
What are the four kinds of hormone?
Monoamine - catecholamines
Peptide -
Protein - eg. thyroid hormone
Steroid - sex hormones
How do protein and peptides act?
Bind cell membrane
How do steroids act?
bind mRNA -> changes protein synthesis
Give examples of Monoamine hormones
Catecholamines eg. NA, Adr, (may be NT or hormones)
DA - NT
What three levels may hormones act upon?
Sensory
CNS
Effector
Give an example of how hormones affect sensory systems
Testosterone ^ detection of oestrus in the female
How are hormone levels regulated?
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 (?)
Give an example of negative feedback
PTH -> ^ Blood [Ca], [Ca] -> vPTH
Give an example of positive feedback
Stress response, Fergusson reflex, LH
Why are biological rhythms in hormone levels seen?
To synchronise biological function with environmental changes
What is the name for cycles based upon day length? Night length?
Cicadian, Circalunar (for nocturnal species - more active at the full moon)
What are the four main endocrine systems relevant to behavioural problems?
Insulin and glucose metabolism
Thyroid hormoens
Steroid hormones - glucocorticoids and mineralocorticoids
Sex hormones
What are the two functions of sex hormones?
Direct sexual activity directly
Gender differences - females more anxious, males more impulsive
What does castration prepuberty cause in non primates?
Lack of testosterone means will not develop aggressive tendencies
What peripheral endocrine effects do the sex hormones have?
Pubertal changes
eg. cheeks in tom cat
How may sex hormones alter CNS activity?
Act as modulatory NTs - direct and genomic effect on pathway activation, changing likelihood of response to stimulus
What hormone is affected by oestrogen?
ACTH and other stress hormones - change likely to be greater in females
This phenomenon disappears with ovariectomy
Which hormones are involved in aggressive responses?
AVP and CRH
What other effects do sex hormones have on the brain? How may neutering affect this?
-> neural plasticity and synapse formation
^ risk of cognitive dysfunction and long term learning disabilities
How may sex hormones end up in the brain? What kind of effect are they said to have?
Cross BBB Local synthesis from cholesterol Conversion in the brain eg. testesterone -> oestrogen; progesterone -> pregnanolone (active metabolite) - Tonic effect
What are the four stages of oestrus in the bitch?
Pro-oestrus, Oestrus (LH spike, will stand), Metoestrus (pregnancy, ~ 7 months), Anoestrus
What occurs pre-season in the bitch? How may this affect behaviour?
3 weeks pre-season, ^FSH/LH -> ^E2
Moody, irritable, very attractive to males
When in season bitches may urine mark