2024 RX411 Live Session 1: Pituitary Hormones

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Questions and Answers

What is the major hormone responsible for stature growth?

Insulin-like Growth Factor 1 (IGF-1) (correct)

Testosterone

Estrogen

Growth Hormone (GH)

What effect do sex steroids have on IGF-1 production?

Destroy cartilage

Stimulate production from cartilage (correct)

Inhibit production from cartilage

Have no effect on production

What is a consequence of prepubertal sex steroid excess?

Adult short stature (correct)

Increased muscle mass

Prolonged growth phases

Delayed sexual maturation

How do growth hormone (GH) and IGF-1 differ with respect to blood glucose levels?

GH increases, IGF-1 decreases Signup and view all the answers

What body proportion abnormality arises from prepubertal sex steroid deficiency?

Span>height, upper:lower segment ratio < 0.9 Signup and view all the answers

What does the FDA approval of recombinant bovine GH (rBGH) aim to achieve?

Increase milk production Signup and view all the answers

What potential impact might residual rBGH have on humans?

Lead to growth acceleration Signup and view all the answers

Which of the following describes the effects of GH and IGF-1 on protein synthesis?

Both stimulate protein synthesis Signup and view all the answers

Why is somatropin administered in the evening?

It mimics natural growth hormone release patterns. Signup and view all the answers

What contributes to the longer biological half-life of modified GH analogs?

Structural alterations like albumin binding. Signup and view all the answers

Which of the following conditions might indicate effective response to growth hormone treatment?

Increase in IGF-1 levels. Signup and view all the answers

What is a potential consequence of excessive use of growth hormone without medical supervision?

Hyperglycemia and insulin resistance. Signup and view all the answers

Which GH analog was approved for pediatric patients with growth failure due to low endogenous GH?

Lonapegsomatropin-tcgd Signup and view all the answers

Which of the following is a reason growth hormone is listed as a banned substance by WADA?

It can lead to unfair advantages in performance. Signup and view all the answers

What is a common monitoring practice during growth hormone therapy?

Measuring IGF-1 levels. Signup and view all the answers

What is the primary use of somatropin in patients?

For growth hormone deficiency. Signup and view all the answers

What hormone does the hypothalamus release to stimulate the anterior pituitary's secretion of growth hormone?

GHRH Signup and view all the answers

Which hormone is responsible for inhibiting growth hormone release?

Insulin-like growth factor-1 Signup and view all the answers

Where are hormones synthesized in the posterior pituitary?

Hypothalamic neurons' cell bodies Signup and view all the answers

Which hormone does NOT originate from the anterior pituitary?

Oxytocin Signup and view all the answers

What is the primary action of growth hormone (GH) on the body?

Stimulates conversion of energy for muscle and bone mass Signup and view all the answers

Which of the following is NOT a hormone released from the anterior pituitary?

ADH Signup and view all the answers

What role does ghrelin play in the regulation of growth hormone?

It stimulates GH release. Signup and view all the answers

What is the function of insulin-like growth factor-1 (IGF-1) in relation to growth hormone?

It inhibits GH secretion. Signup and view all the answers

What role do somatostatin receptor agonists like octreotide and lanreotide play in the treatment of acromegaly?

They act as long-acting somatostatin receptor agonists. Signup and view all the answers

What is the primary use of pegvisomant in the management of acromegaly?

To inhibit GH from binding to its receptor. Signup and view all the answers

Which of the following statements about kisspeptin and its role in puberty is correct?

Kisspeptin receptors are found on GnRH neurons. Signup and view all the answers

What distinguishes synthetic GnRH agonists from antagonists?

Agonists stimulate pituitary hormone release. Signup and view all the answers

What is a common effect of a mutation in kisspeptin receptors?

Failure to initiate puberty. Signup and view all the answers

Which characteristic is associated with the half-life (T1/2) of GnRH?

It is approximately 4 minutes. Signup and view all the answers

Which is an example of a synthetic GnRH antagonist?

Ganirelix Signup and view all the answers

How does the secretion of FSH and LH change during the menstrual cycle in females?

It is dependent on the frequency and amplitude of GnRH pulses. Signup and view all the answers

What effect does increased pulse frequency of GnRH have on FSH and LH secretion?

Increases secretion of both hormones. Signup and view all the answers

Which of the following is true regarding long-acting formulations of somatostatin receptor agonists?

They have a longer duration of action compared to short-acting formulations. Signup and view all the answers

What is the primary clinical use of GnRH receptor agonists like Leuprolide and Goserelin?

To treat hormone-sensitive cancers Signup and view all the answers

Which of the following is a potential advantage of GnRH receptor antagonists over GnRH agonists in IVF?

They provide immediate effects Signup and view all the answers

What hormone is primarily affected by continuous administration of GnRH agonists?

FSH and LH Signup and view all the answers

Which drug is approved for the treatment of endometriosis?

Elagolix Signup and view all the answers

What effect does pulsatile administration of GnRH have on the anterior pituitary?

Increased release of FSH and LH Signup and view all the answers

What is the purpose of administering hCG in controlled ovarian hyperstimulation?

To induce final oocyte maturation and ovulation Signup and view all the answers

Which of the following is a common adverse effect of GnRH receptor antagonists?

Nausea Signup and view all the answers

Why might a patient experience an initial increase in testosterone levels when treated with leuprolide?

It causes a temporary surge in hormone levels Signup and view all the answers

Study Notes

Anterior vs. Posterior Pituitary Hormones

Anterior pituitary hormones are synthesized and released into systemic circulation, whereas posterior pituitary hormones are produced in the hypothalamic cell body and transported via axon terminals for release.
Primary anterior pituitary hormones include Growth Hormone (GH), Thyroid Stimulating Hormone (TSH), Adrenocorticotropic Hormone (ACTH), Gonadotropins (LH & FSH), and Prolactin (PRL).
Posterior pituitary hormones primarily consist of Oxytocin and Antidiuretic Hormone (ADH, also known as vasopressin).

Hypothalamic-Pituitary-Growth Hormone (GH) Axis

GH release is influenced by hypothalamic factors: GHRH (growth hormone-releasing hormone) increases GH release, while SST (somatostatin) decreases it.
Ghrelin, a gastric peptide, stimulates GH release.
GH acts directly on target tissues and indirectly via Insulin-like Growth Factor 1 (IGF-1), which also provides negative feedback to inhibit GH and GHRH release.

Physiological Effects of GH and IGF-1

GH promotes energy conversion from sugars and fats into muscle and bone mass, leading to anabolic effects.
IGF-1 plays a significant role in growth and development, mirroring GH's effects on protein synthesis and bone growth but differing in effects on glucose and lipid levels.

Effect of Sex Steroids on Growth

Sex steroids stimulate IGF-1 production from cartilage and influence long bone growth.
Excess prepubertal sex steroids can lead to premature sexual maturation, growth acceleration, and eventual epiphyseal closure, resulting in shorter adult stature.
Deficiency in prepubertal sex steroids may lead to abnormal body proportions such as height span discrepancies.

GH Use in Dairy Production

Recombinant bovine GH (rBGH) was approved by FDA in 1993 to enhance milk production in cows.
Questions regarding the health impacts of consuming milk from rBGH-treated cows arise if residual rBGH enters the human body and its association with conditions like Laron dwarfism.

Growth Hormone Therapy

Somatropin (recombinant human GH) is administered subcutaneously, typically once daily in the evening for children and adults with GH deficiency.
Long-acting GH analogs have been developed, such as Somapacitan, Lonapegsomatropin, and Somatrogon, which have improved half-lives making them suitable for less frequent dosing.

Treatment of Acromegaly

Acromegaly can be treated with somatostatin receptor agonists (e.g., Octreotide, Lanreotide), surgery, or Pegvisomant, a GH receptor antagonist that prevents receptor activation.
Peptides that target the IGF-1 receptor are being investigated for potential new treatments.

Hypothalamic-Pituitary-Gonadal Axis

Kisspeptin stimulates gonadotropin-releasing hormone (GnRH) secretion, which increases at puberty.
GnRH secretion is regulated by its pulse frequency and amplitude, affecting FSH and LH levels in both males and females.

Synthetic GnRH Agonists and Antagonists

Synthetic GnRH agonists (e.g., Leuprolide, Goserelin) have longer half-lives compared to natural GnRH, facilitating clinical use.
GnRH antagonists (e.g., Ganirelix, Cetrorelix) provide immediate effects, useful in assisted reproductive technologies to prevent premature ovulation.

Controlled Ovarian Hyperstimulation

Human chorionic gonadotropin (hCG) is administered to induce ovulation when mature oocytes are identified.

Adverse Effects and Considerations

Excessive growth hormone use may lead to various adverse effects, including metabolic disturbances.
Monitoring IGF-1 levels is critical in assessing GH treatment efficacy, and understanding the pharmacodynamics of medications like leuprolide is essential for managing patients effectively.

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Description

This quiz covers the differences between anterior and posterior pituitary hormones, focusing on their functions and regulatory mechanisms. Gain insights into how hypothalamic neurons influence hormone release and synthesis. Perfect for students of pharmacy and medical sciences.