Modules 1.1-1.4 Reproductive Behaviour and Libido Flashcards
Which region of the hypothalamus regulates sex drive/libido?
The Medial Preoptic Area (MPOA) of the Anterior hypothalamus
The medial preoptic area is one source of what hormone?
The medial preoptic area is one source of GnRH (which stimulates sex steroid production)
Which regions of the hypothalamus have high numbers of androgen and estrogen receptors?
The hypothalamic region as well as the ventromedial nucleus
- ties into the integration of reproductive function in which GnRH acts to eventually support gonadal function including production of sex hormones which can then act on multiple sites in the brain (including the MPOA)
How was the median-preoptic region (MPOA) discovered as a mediator of sex drive?
Lesion of the MPOA which lead to disrupted sexual behaviour
Disrupted Appetitive behaviours
- Solicitation - females
- timing and spacing of Lordosis - females (exaggerated curvature of the spine)
- Sexually rewarded maze learning in males
- if male successfully completes maze they can mate
- viewed as analogous to desire in humans
Which behaviours were disrupted by lesion of the medial preoptic area?
Disrupted Appetitive behaviours
- Solicitation - females
- timing and spacing of Lordosis - females (exaggerated curvature of the spine)
- Sexually rewarded maze learning in males
- if male successfully completes maze they can mate
- viewed as analogous to desire in humans
What is the role of sex hormones in sexual desire/libido?
In both males and females, androgens are associated with increased libido
- eliminated endogenous androgens (castration or ovariectomy) abolishes sexual desire
______ hormones act centrally and peripherally to ensure a sexually relevant stimulus is more likely to elicit a sexual response
Steroid hormones act centrally and peripherally to ensure a sexually relevant stimulus is more likely to elicit a sexual response
Steroid hormones act ______ and ______ to ensure a sexually relevant stimulus is more likely to elicit a sexual response
Steroid hormones act centrally and peripherally to ensure a sexually relevant stimulus is more likely to elicit a sexual response
Sexual hormones modulate _________ release
Sexual hormones modulate central neurotransmitter release
- Especially dopamine
- highly implicated in both male and female sexual behaviour
Sex hormones stimulate _____[neurotransmitter]____ release which has been demonstrated in males and females
Sex hormones stimulate central dopamine release which has been demonstrated in males and females
Central dopamine release occurs in the ________ of the hypothalamus
Central dopamine release occurs in the MPOA (medial preoptic area) of the hypothalamus
- Recall: region features numerous neurons responsive to androgens and estrogens
Sex hormones bind to receptors in the ___[region of hypothalamus]__ and trigger _____
Sex hormones bind to receptors in the MPOA and trigger dopamine release and facilitation of the sex drive
Sex hormones are thought to prime sensory processing in the brain to be receptive to sexually relevant stimuli
How are sex hormones are thought to prime sensory processing in the brain
Sex hormones are thought to prime sensory processing in the brain to be receptive to sexually relevant stimuli
What happens if dopamine signalling in the MPOA is disrupted (eg you inject a dopamine antagonist into the MPOA)
- Decrease in sexual motivation
What does measuring dopamine levels during pre-copulation show? What does this indicate?
Dopamine in MPOA rises in the pre-copulatory period in male and female rats indicating a role in sexual motivation
- psychiatric disorders that disrupt central dopamine signalling are often associated with low libido and in some cases sexual dysfuntion
Attraction is primarily associated with _______ and ________
Attraction is primarily associated with catecholamines and dopamine signaling in the brain
Romantic attraction is associated with:
- Increased monoamine NT’s
- dopamine, norepinephrine (derived from DA)
- In the mesolimbic (reward centres) of the brain
Results of increased central dopamine? (2)
- Euphoria, loss of appetite, hyperactivity, increased mental activity, decreased need for sleep
- Heightened motivation and goal-directed behavior
- Increased dopamine is likely associated with increased passionate attraction in humans
Attachment is associated primarily with _____ and _____
Attachment is associated primarily with vasopressin and oxytocin
Vasopressin and oxytocin are peptides released in the ____ and produce _____
Vasopressin and oxytocin are peptides released in the CNS and produce produce monogamous male-female attachment and monogamous parenting behaviour
From a neuroscientist point of view, attachment is thought to depend on ________; why?
From a neuroscientist point of view, attachment is thought to depend on sexual intercourse (consummatory actions)
- It’s upon copulation that vasopressin and oxytocin are released in the brain thus facilitating development of attachment
- Not necessarily true in humans
Which hormone facilitates the pair bond in males? Females? (prairie voles)
Males - vasopressin
Females - oxytocin
Where do the hormones vasopressin and oxytocin act in the brain?
- Oxytocin receptors are rich in nucleus accumbens and prefrontal cortex
- Vasopressin receptors in ventral pallidum
- Areas included in the central reward circuits
How are oxytocin and vasopressin related to human attachment?
- Increased oxytocin release following orgasm
- Increased vasopressin release during sexual arousal in males
- Sex may not be essential for bond formation but may be facilitative (ie may play a permissive role)
