An Introduction to Neuroendocrinology Flashcards
What is Neuroendocrinology?
- Part of endocrinology involving brain and nerves
* Mostly about hypothalamus and pituitary gland
What is endocrinology?
- science of hormones and all the glands and cells that release them
- This includes gonads and prostate, thyroid gland, adrenal glands, pineal gland, pancreas and so on.
- Every single organ is influenced by hormones
Definition: Hormones
- any member of a class of signaling molecules in multicellular organisms
- long-distance messenger regulating physiology and behavior
*the same substance may be either neurotransmitter or hormone, depending on the mode of release
(*neurotransmitters are short-term messengers, and tissue-factors in-between)
What are the properties of hormones?
- produced by dedicated endocrine cells
- released into the bloodstream
- effectuates functional and/or structural changes in a target cell after receptor binding
Name hormones by their chemical composition!
amino acids, peptides, steroids and eicosanoids
What are the properties of steroids? (4)
- enzymatic derivates of cholesterol
- steroid hormones are lipophilic (no polarity) and pass through the cellular membrane
- not transcribed from DNA
- steroid receptors are rare in CNS and scattered throughout the cortex
AIS
- androgen insensitivity syndrome = “testicular feminization”
- mutations of testosterone receptors, resulting in XY genotype with female phenotype
Androgenes and Estrogenes
- level of embryonic androgens (e.g. testosterone) and estrogens (e.g. estradiol) control the expression of male or female phenotypes
- androgens also produced by adrenal glands
- both androgens and estrogens present in all individuals, yet at differing concentrations
What are the functions of the hypothalamus?
- integration of information from forebrain, brainstem, spinal cord, and intrinsic chemosensitive neurons
- maintaining homeostasis: comparing input with biological set points and activating adjusting responses
- also involved in…
- control of blood flow
- regulation of energy metabolism
- reproductive activity
- responses to threat
Characteristics of hypothalamus?
- floor and ventral wall of the third ventricle
- consists of at least 14 nuclei
- grouping along sagittal axis: anterior (= preoptic) – tuberal – posterior regions
- grouping along medio-lateral axis: periventricular – medial – lateral groups
Posterior Pituitary Gland (location and function)
- extension (axons) of neurons in supraoptic and paraventricular nuclei (medial-tuberal region) (or short: extension of hypothalamus)
- releases oxytocin and vasopressin into bloodstream
What is the Anterior Pituitary Gland?
+ example of hormones it secretes!
- completely distinct embryologic origin than posterior pituitary
- migrates to fuse with the posterior pituitary during pre-natal development
*it releases e.g. LH & FSH in response to gonadotropin-releasing hormone, GnR (hypothalamic releasing/inhibiting factor)
Which hormones stimulate the gonads and what do they induce?
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) induce…
- formation of oocytes and sperm
- the level of sex hormones
Which hormones stimulate the mammillary gland and what do they induce?
- prolactin induces milk-production
* oxytocin induces milk ejection
Which hormones stimulate the adrenal glands and what do they induce?
Adreno-corticotrope hormone (ACTH) induces…
- release of cortisol (stress response and nutrient balance)
- release of aldosterone (fluid balance via kidneys)
