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Nathan Goodyear

Salivary Testosterone and a Trinucleotide (CAG) Length Polymorphism in the Androgen Rec... - 0 views

www.ncbi.nlm.nih.gov/...PMC2825741

CAG androgen receptors AR androgen receptor Testosterone hormone hormones male men

shared by Nathan Goodyear on 22 Jun 15 - No Cached
  • Testosterone correlated inversely with participant age (r = −0.39, p = 0.012) and positively with number of CAG repeats
  • transactivation potential of the AR appears to decline in graded relation to an increasing number of CAG repeats, which are distributed over a normative range of 11–37 and, in Caucasian populations, commonly average 21–22 repeats
  • When activated by androgens, ARs translocate to the cell nucleus, where they exert transcriptional control of androgen-dependent genes by binding to androgen response elements within gene regulatory sequences
  • ...10 more annotations...
  • some evidence suggests a high number of CAG repeats may be associated with cognitive aging
  • androgens (like other steroid hormones) promote or repress the expression of genes specifying an array of cellular proteins
  • diurnal variation in testosterone levels
  • salivary testosterone correlated negatively with participant age and positively with CAG length variation in the AR gene
  • CAG repeat number varied inversely with reactivity of the ventral amygdala to facial expressions of negative affect
  • higher salivary testosterone was likewise associated with a greater number of AR CAG repeats
  • relative androgen insensitivity in ARs with a larger number of CAG repeats
  • Because circulating testosterone is regulated via negative feedback through the hypothalamic-pituitary-gonadal axis, diminished androgen sensitivity at higher CAG repeat lengths may reduce feedback suppression of luteinizing hormone (LH). LH would then be maintained at higher levels, in turn promoting higher testosterone production
  • Testosterone up-regulates AVP expression in the amygdala
  • Oxytocin exerts an inhibitory influence on AVP expression in the central amygdala, and the synthesis of oxytocin is mediated by estrogen and estrogen receptors
  • Nathan Goodyear on 22 Jun 15
     
    Study used saliva to measure Testosterone levels in men.  Testosterone levels were inversely associated with age, but positively associated with CAG repeat sequences in the AR.
Nathan Goodyear

Effect of vasopressin 1b receptor blockade on the hypothalamic-pituitary-adrenal respon... - 0 views

joe.endocrinology-journals.org/...285.full.pdf

stress HPA hypothalamus pituitary axis hypothalamic-pituitary chronic CRH AVP vasopressin

shared by Nathan Goodyear on 03 Oct 12 - No Cached
  • Nathan Goodyear on 03 Oct 12
     
    repeated stress results in down regulation of central stress response ie. blunted CRH response.
Nathan Goodyear

Sex, Receptors, and Attachment: A Review of Individual Factors Influencing Response to ... - 0 views

www.ncbi.nlm.nih.gov/...PMC3541513

Oxytocin libido hormone hormones sex

shared by Nathan Goodyear on 29 Jul 13 - No Cached
  • Estrogen upregulates OT and OT receptor (OTR) production
  • testosterone promotes both OTR binding in the hypothalamus (Johnson et al., 1991) as well as production of AVP (Delville et al., 1996), which has many opponent actions to OT
  • men and women show differences in plasma OT levels
  • Nathan Goodyear on 29 Jul 13
     
    Oxytocin and libido.
Nathan Goodyear

Which Patients Do Not Require a GH Stimulation Test for the Diagnosis of Adult GH Defic... - 0 views

press.endocrine.org/...jcem.87.2.8216

HGH GH human growth hormone growth hormone IGF-1

shared by Nathan Goodyear on 04 Nov 14 - No Cached
  • Four studies have reported that the probability of GHD (peak GH criteria ranging from < 2.3 to < 5 μg/liter) in patients with three to four PHDs ranges from 91% to 100%
  • 95% accuracy by the presence of either three or more PHDs or a serum IGF-I concentration less than 84 μg/lite
  • adult GHD could be predicted with 95% accuracy by the presence of either three or four PHDs or a serum IGF-I concentration less than 84 μg/liter
  • ...5 more annotations...
  • Hypopituitary adults with GHD have been reported to have normal serum IGF-I levels in 37–70% of patients in various studies (5, 9, 18, 21, 22). This is owing in part to the fact that multiple factors regulate serum IGF-I concentrations including nutritional status; hepatic and renal function; and circulating concentrations of thyroid hormone, androgens, and estrogens
  • changes in concentrations of IGF-binding proteins (IGFBPs) influence the total concentration of IGF-I in plasma
  • Among patients with an IGF-I sd score above −1 in the present study, 46% had a peak GH less than 2.5 μg/liter and 67% had a peak GH less than 5 μg/liter.
  • In summary, adult GHD can be predicted with 95% accuracy by the presence of either three or four PHDs or a serum IGF-I concentration less than 84 μg/liter
  • We propose that adult patients with three or four PHDs (three or four of the following deficiencies: TSH, ACTH, gonadotropins [LH and/or FSH], and AVP [central diabetes insipidus]) do not require a GH stimulation test to make the diagnosis of adult GHD
  • Nathan Goodyear on 04 Nov 14
     
    Insulin Tolerance Test is the gold standard for HGH diagnosis, but this an unpopular test do to long list of side effects.  This study finds a 95% accuracy for IGF-1 less than 84 with 3 or more coexisting pituitary hormone deficiencies.
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