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NEUR454 > Chapter 5 > Flashcards

Chapter 5 Flashcards

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1
Q

when is male sex drive expressed?

A

male sex drive is expressed after puberty

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2
Q

male sex drive is expressed after puberty, this timing suggests that:

A

testes involved in sexual motivation

Indeed they are: remove testes in adulthood: no more sexual behaviour

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3
Q

are testes involved in sexual motivation?

A

yes

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4
Q

Remove testes in adulthood, what happens?

A

No more sexual behaviour (dramatically decreases) – indeed testes involved in sexual motivation

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5
Q

remove testes in adulthood, then androgen treatment: what happens?

A

sexual behaviour/motivation will recover

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6
Q

hormones cause behaviour?

A

no- hormones dont cause behaviour they change the probability

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7
Q

Hormones and experience interact to affect

A

behavior

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8
Q

Male sexual behavior involves 2 phases:

A
  1. Appetitive phase (Seeking)
  2. Consummatory phase (Acting)
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9
Q

males spend majority of their time in:

A

appetitive phase

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10
Q

Copulation takes place in which two phases of male sexual behaviour

A

copulation takes place in the consummatory phase

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11
Q

hormones impact what phases of male sexual behaviour

A

impact both phases

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12
Q

What are the three components of the consummatory phase

A
  1. Mounting
    2.Intromission
    3.Ejaculation
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13
Q

describe mounting (1/3) component of consummatory phase

A

Male is hovering behind female: female needs to be in lordosis position (arching back): allowing mounting, mounting is not intermission: penis not inside vagina: male hovering over female and is grabbing her by the flanks

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14
Q

After ejaculation, male

A

ignores female

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15
Q

The time btw ejaculation and next copulatory series is called

A

post-ejaculatory interval (PEI)

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16
Q

PEI composed of 2 periods

A

absolute and relative refractory phase

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17
Q

absolutory refractory phase of PEI:

A

no other way male will engage in copulatory behaviour with anyone

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18
Q

reflexive refractory phase

A

male might engage in copulatory behaviour if stimulus strong enough (ex: novel female)

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19
Q

Coolidge Effect

A

Following copulation, male will not engage in copulating behaviour with the female they just mounted but might copulate with a novel female

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20
Q

3 components of consummatory phase: mounting, intermission and ejaculation do not disappear all at same time when you castrate

A

: first thing to disappear 1) ejaculation 2)intromission and lastly mounting disappears

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21
Q

3 components of consummatory phase: mounting, intermission and ejaculation do not disappear all at same time when you castrate: first thing to disappear 1) ejaculation 2)intromission and lastly mounting disappears
Once you start androgen treatment it is :

A

the mirror effect: mounting reappears first, then intromission and lastly ejaculation

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22
Q

the three components of the consummatory phase (mounting, intromission, ejaculation) do not dissapear and reappear at the same time (when remove androgen and when start retreating with androgens), what this is telling us is:

A

each of these components of the consummatory phase has different sensitivity to androgens

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23
Q

During organization of the CNS in males it is __ that is masculinizing**

A

testosterone being converted into estrogen

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24
Q

in rodents, since testosterone (an androgen) is being converted to estradiol (an estrogen), can we assume estrogen is the single important thing?

A

estrogen in regards to copulatory behaviour in adulthood is important but it is not estrogen alone: we know this because if u treat castrated males with testosterone or androstenione you can recover overall sexual mating behaviour in the males
If instead you treat males with DHT you dont recover male sexual behaviour (DHT cant be converted into estradiol)

DHT on its own can no recover sexual behaviour

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25
DHT important for
penile reflexes
26
can DHT recover sexual behaviour on its own?
no
27
best mix to recover male sexual behaviour (2 options):
1)testosterone or androstenedione (both can be converted to DHT via reductase or to estradiol via aromatase) 2)estrogen+ DHT
28
__ and __ can maintain mating behaviour after castration
Testosterone and androstenedione
29
* Injecting castrated rats with __ renders subsequent androgen therapy ineffective
estrogen receptor blocker
30
Injecting castrated rats with estrogen receptor blocker renders subsequent androgen therapy ineffective * Similar results if
blocking aromatization
31
aside from testosterone and androstenedione, __ and __ can fully restore copulation in castrates
estrogen and DHT
32
MPOA is important for
regulation of male sexual behavior (lesion/stimulation)
33
lesion MPOA:
no more male copulatory behaviour
34
electrically stimulate MPOA:
stimulate male copulatory behaviour
35
what exactly are hormones doing in the MPOA:
Indirectly they lead to extracellular dopamine levels in MPOA Heightened dopamine in MPOA extremely important in male sexual behaviour In humans we know that if levels of dopamine in this area increase through a dopamine agonist (L-dopa) results in increase in engaging sexual behaviour
36
The effects of androgens on male sexual behavior might be in part modulated here
MPOA
37
MPOA stands for
medial preoptic area (an area in hypothalamus)
38
relevance DA agonists in male sexual behaviour
DA agonists injected into MPOA facilitate sexual behavior
39
relevance DA antagonists in regards to male sexual behaviour
* DA antagonists injected into MPOA impair copulation, genital reflexes and sexual motivation
40
Testosterone may promote copulation via
impact on DA release in MPOA
41
study 1/4 "extracellular dopamine in the MPOA; implication for sexual motivation and hormonal control. of copulation": aim:
Wanted to see if treating animals with a hormone vs with a placebo would impact male sexual behaviour in male and also extracellular dopamine levels in MPOA and if there is a link between the two
42
Study 1/4: "extracellular dopamine in the MPOA; implication for sexual motivation and hormonal control. of copulation" . PART 1 aim:Does extracellular MPOA DA increase during a precopulatory period and/or copulation?
Some animals were castrated and other ones were not (control), some of the castrated were treated with androgens and others were treated with a placebo (oil) Observed: All groups show increase from dopamine level baseline during precop and all copulatory phases except for group at bottom (a group treated with placebo: dopamine levels in MPOA do not increase) no copulatory behaviour The other castrated group (given the vehicle): still engaging in male sexual behaviour: show heightened dopamine in MPOA: remember you castrate animals it is not automatic: animals can still engage in sexual behaviour for a few days interestingly in brain at same time show heightened dopamine in MPOA: in parallel to fact that they are still copulating: showing heightened dopamine in MPOA No dopamine in MPOA: no sexual behaviour Dopamine in MPOA: sexual behaviour
43
Experiment 1/4: "extracellular dopamine in the MPOA; implication for sexual motivation and hormonal control of copulation" . PArt 2 AIM: Do non-sexual social stimuli account for the precopulatory DA↑?
Could increase in precop phase not due to estrous female on other side but merely because there is a social stimulus on other side (another rodent regardless of sex provides social cue): experimenters exminedthis: Had male on other side of plexiglass: dopamine increased slightly but not as much Experiment 2 tells us that extracellular dopamine levels in experiment one during precop phase is because there is a receptive FEMALE on other side
44
Experiment 1/4: "extracellular dopamine in the MPOA; implication for sexual motivation and hormonal control of copulation" . PART 3 AIM:3. Is the motor activity of copulation what accounts for DA↑ during copulation?
Here we are questioning if it Is the MOVEMENT increasing dopamine levels In experiment 3 Had animals have access to running wheels for a few days prior to measuring dopamine and had access to wheel on experiment day: dopamine increases in other regions of brain but they measure dopamine levels in MPOA specifically: dopamine levels increased to a certain extent compared to baseline after running but not as much as copulating
45
Experiment 1/4: "extracellular dopamine in the MPOA; implication for sexual motivation and hormonal control of copulation" CONCLUSIONS (4):
(1) More than half the 1-week castrates showed precopulatory DA↑ and copulated (Hormones were not directly present had been present not long ago still showed copulation and that was in parallel to showing increase in dopamine in MPOA) (2) DA↑ specific to ♀ (receptive female not just any social cue) stimulus + copulation (not just locomotion) (3)Two-weeks after castration no DA response + no copulation (4)The DA response to receptive female and copulatory behavior seem to depend on the recent presence of testosterone
46
Study 2: Testosterone restoration of copulatory behaviour correlates with medial preoptic dopamine release in castrated male rats: Aim
* Examine the impact of length of testosterone treatment on the restoration of copulation and DA MPOA in castrated male rats
47
Study 2: Testosterone restoration of copulatory behaviour correlates with medial preoptic dopamine release in castrated male rats: Describe
In this study males were castrated and experimenters waited 3 weeks (all sexual behaviour extinguished and no increase in extracellular MPOA ) After 3 weeks start treating animals (no recency effects of androgens) either for 2,5 or 10 day
48
Study 2: Testosterone restoration of copulatory behaviour correlates with medial preoptic dopamine release in castrated male rats: behavioural results:
* Five days of testosterone administration was sufficient for copulatory and MPOA DA recovery in most castrates * Complete behavioral and MPOA DAergic recovery was found in castrates treated with testosterone for 10d (2 days not enough)
49
For male sexual behaviour to take place __
dopamine levels must be high
50
Thalamus important relay station for sensory stimuli but not important in
olfactory cues
51
How do chemical messengers impact the male (4 important structures):
Female pheromones go to VNO:VNO neurons project to accessory olfactory bulb -> medial amygdala -> to various hypothalamus regions IMPORTANTLY MPOA
52
synonym lateral amygdala:
olfactory amygdala
53
synonym medial amygdala:
vomeronasal amygdala
54
olfactory cue in general pathway:
Olfactory cue in general from olfactory mucosa to main olfactory bulb to different cortical regions to lateral amygdala
55
Ultimately chemosensory information about receptivity female goes to
MPOA
56
Study 3: Chemosensory cues are essential for mating-induced dopamine release in MPOA of male syrian hamsters: aim:
* Determine if chemosensory cues are necessary for MPOA DA release during mating in Syrian hamsters. 4 types of olfactory bulbectomys
57
Study 3: Chemosensory cues are essential for mating-induced dopamine release in MPOA of male syrian hamsters: 4 groups:
* Sham olfactory bulbectomy * Bilateral bulbectomy * Ipsilateral bulbectomy * Contralateral (to where probe inserted) bulbectomy
58
Study 3: Chemosensory cues are essential for mating-induced dopamine release in MPOA of male syrian hamsters: results
sham group: dopamine levels in MPOA increase during mating bilateral bulbectomy: dopamine levels in MPOA do not increase ipsilateral bulbectomy: no increase in dopamine level in MPOA but animals are still mating because bulb on other side is still there so pheromones can travel to MPOA on other side contralateral bulbectomy: Dopamine increase in MPOA on side being measured
59
59
an experiment looked at neuronal firing in olfactory bulbs and MPOA in response to two stimulus estrous female urine (contains pheromones) or apple scent (control): intact animals showed what kind of firing in olfactory bulb vs in mpoa
In olfactory bulb: no matter the scent the neurons are firing that is not true for MPOA: neurons MPOA only fire for sexual cues
60
61
an experiment looked at neuronal firing in olfactory bulbs and MPOA in response to two stimulus estrous female urine (contains pheromones) or apple scent (control): castrated animals showed what kind of firing in olfactory bulb vs in mpoa
Castrated ANIMALS (remove androgens) Neurons olfactory bulb: continue to fire regardless of scent In MPOA :estrous rat urine no longer has same effect on neuron firing.
62
an experiment looked at neuronal firing in olfactory bulbs and MPOA in response to two stimulus estrous female urine (contains pheromones) or apple scent (control): end results of the study showed:
The gonads and the hormone they release impact neurons firing in MPOA in regards to estrous rat urine, absence hormones makes the neurons in mpoa not sensitive to female cues When treat castrated with androgens: recovery of normal sensitivity to female in MPOA
63
MPOA receives __ sensory input from __
MPOA receives indirect sensory input from virtually every sensory modality
64
MPOA has __ with each source of input
reciprocal connections
65
Both MPOA ___ are critical for the initiation of copulation
Both MPOA afferent and efferent connections are critical for the initiation of copulation
66
* Steroid hormone receptors in MPOA and its afferent connections enable hormones to promote the processing of
sexually relevant stimuli
67
__ tends to inhibit male sexual behavior
serotonin
68
During ejaculation, increased serotonin secretion in __ does what
During ejaculation, increased serotonin secretion in MPOA inhibits DA, which reduces male sexual behavior
69
describe the study on Individual differences and male reproductive behavior
some males had higher sex drive than others: separated them (red – high drive, blue- medium drive and low drive), then they castrated all males (got rid of main source of androgens), following castration after some time the sex drive is gone for all of them, then they inject animals with testosterone, slowly (not immediately); we see recovery of sex drive in all three groups (started with low dose), however this recovery in sex drive is not identical to sex drive that groups were expressing before castration: the QUANTITY of androgens is not directly related to sex drive: if it were: all the groups would be showing same amount of sex drive post castration because they are all given same low dose. Then following low dose, they are all give the same higher dose: overall they continue to show same difference and the sex drive does not go higher up (this tells us that there is a threshold for androgen and high sex drive: you can bombard them with androgen and still not see a higher sex drive)
70
is there a threshold for androgen quantity and sex drive?
yes

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