19 Questions
What is the main factor in controlling reproduction in most mammals?
Season
Which genetic defect is studied using hypogonadal (hpg) mice as an animal model?
Kallmann’s Syndrome
What is the function of gonadotropin releasing hormone (GnRH) produced by hypothalamic neurons?
Stimulate production of gonadotropins from the anterior pituitary
What animal model is used to study the genetic defect in GnRH production, Kallmann’s Syndrome?
Hypogonadal (hpg) mice
What disrupts the estrus cycle by affecting the release of GnRH from the hypothalamus/pituitary?
Ablation of SCN
What controls seasonal reproduction in most mammals?
Melatonin production
What hormone is responsible for affecting the function and size of gonads?
Melatonin
What is the main factor in regulating melatonin synthesis?
Photoperiodicity
What animal model is used to study the genetic defect in GnRH production, Kallmann’s Syndrome, and can have gonadal function restored with pulsatile GnRH?
Hypogonadal (hpg) mice
What is the impact of exposure of pituitary to continuous GnRH?
Downregulation of GnRH receptors
What is the role of inhibin in the pituitary?
Suppress FSH release
What can chronic stress do at hypothalamic and pituitary levels?
Suppress pulsatile release of GnRH and LH
What is the impact of ovarectomy (OVX) on synaptic input on GnRH neurons?
Decreases synaptic input on GnRH neurons
How does feedback control of GnRH release impact pulse frequency of GnRH and LH?
Decreases pulse frequency of GnRH and LH
What is the impact of estradiol and testosterone on LH pulses?
Decrease LH pulses by reducing sensitivity to GnRH
What is the impact of menopause on LH and FSH?
High LH/FSH due to depletion of ovarian follicles
What is the role of inhibin in the pituitary?
Suppress FSH release
What are the factors causing alterations in ovarian function?
Menopause, tissue damage, circadian rhythms, environmental input
What is the impact of environmental polymodal hypothalamic input on ovarian function?
Can disrupt ovarian cycle or spermatogenesis
Study Notes
Reproduction Control in Mammals
- The main factor controlling reproduction in most mammals is the hypothalamic-pituitary-gonadal (HPG) axis.
Gonadotropin Releasing Hormone (GnRH)
- GnRH is produced by hypothalamic neurons and regulates the release of gonadotropins from the pituitary gland.
- GnRH is responsible for affecting the function and size of gonads.
Kallmann's Syndrome
- Kallmann's Syndrome is a genetic defect in GnRH production.
- Hypogonadal (hpg) mice are used as an animal model to study this defect.
- Another animal model used to study Kallmann's Syndrome is the hpg mouse, which can have gonadal function restored with pulsatile GnRH.
Estrus Cycle and Melatonin
- The estrus cycle can be disrupted by affecting the release of GnRH from the hypothalamus/pituitary.
- Melatonin synthesis is regulated by the suprachiasmatic nucleus (SCN) and is the main factor in controlling seasonal reproduction in most mammals.
Pituitary and GnRH
- Continuous exposure of the pituitary to GnRH can lead to desensitization and down-regulation of GnRH receptors.
- Inhibin, produced by the gonads, plays a negative feedback role in the pituitary, regulating GnRH release.
Stress and Ovarian Function
- Chronic stress can disrupt GnRH release at hypothalamic and pituitary levels.
- Ovarectomy (OVX) can alter synaptic input on GnRH neurons.
Feedback Control and Hormone Regulation
- Feedback control of GnRH release impacts pulse frequency of GnRH and LH.
- Estradiol and testosterone can modulate LH pulses.
- Menopause is associated with changes in LH and FSH levels.
Ovarian Function and Environmental Factors
- Factors such as environmental polymodal hypothalamic input can alter ovarian function.
- Alterations in ovarian function can be caused by a combination of genetic, hormonal, and environmental factors.
Test your knowledge of neuroendocrine control with this quiz covering the brain-pituitary-gonadal axis, stress-adrenal axis, and the hypothalamus-pituitary-gonad axis. Explore topics like gonadotropin-releasing hormone and the roles of different brain regions in hormonal regulation.
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