Get your Health question answered in 3 easy steps
A Doctor will be with you shortly
Ask a Doctor Now
200 Doctors are Online

Puberty gonadotropins increase, and this increase is attributed to increase in amplitude. Mirrored preceding Gnrh secretion also?

User rating for this question
Very Good
Answered by

Addiction Medicine Specialist
Practicing since : 2002
Answered : 1486 Questions
Question
Hi...I understand before puberty gonadotropins increase, and this increase is attributed to increase in amplitude rather pulses. Is this mirrored in the preceding Gnrh secretion also?

Secondly, i understand exogonous androgens/anabolic steroids during this phase and beyond would suppress the hpg axis...but does it also have a direct second role in helping to establish the Gnrh pulsality and amplitude in the near future??
Posted Mon, 30 Sep 2013 in Thyroid Problem and Hormonal Problems
 
 
Answered by Dr. Preeti Parakh 1 hour later
Brief Answer:
The answer is yes to both your questions.

Detailed Answer:
Hi,

Welcome to Healthcare Magic!

Your first question is regarding puberty. Yes, the increase in gonadotrophin secretion in puberty is mirrored in the preceding Gonadotrophin releasing hormone secretion (GnRH) also. First the GnRH secretion from the hypothalamus increases and then only the gonadotrophin secretion increases. The secretion of both GnRH and gonadotrophin hormones is pulsatile. The cause of increase in GnRH secretion at puberty is not known, but leptin hormone has been implicated.

When the GnRH from the hypothalamus reaches the pituitary gland, it stimulates the secretion of gonadotrophins. This process is controlled by two main factors:
1) Amplitude and frequency of GnRH pulses
2) Negative feedback from androgens and estrogen present in the body

Regarding your second question, exogenous androgens /anabolic steroids suppress both GnRH secretion from hypothalamus and gonadotrophin secretion at the pituitary. Exogenous androgens directly affect the activity of the GnRH pulse generator. Effect of exogenous androgens on gonadotrophin secretion is both direct and also secondary to the effect on GnRH secretion. The effect is so strong that people have studied if exogenous testosterone can be used as a male contraceptive or not.

Hope this answers your query. Please feel free to ask if you want any clarifications.

Best wishes.

Dr Preeti Parakh,
MD Psychiatry
Above answer was peer-reviewed by
 
Follow-up: Puberty gonadotropins increase, and this increase is attributed to increase in amplitude. Mirrored preceding Gnrh secretion also? 10 hours later
Thank you for the great advice.

Just one more question.

During onset of puberty age, do androgens/anabolic steroids play a role in development of Gnrh pulse generator....or is its only role the negative feedback?

Best Regards

 
 
Answered by Dr. Preeti Parakh 24 minutes later
Brief Answer:
No, androgens do not affect pubertal GnRH pulse.

Detailed Answer:
Hi,

Thanks for writing back!

During puberty, adrenal glands secrete androgens like dehydroepiandrosterone even before the GnRH pulse generator becomes active. These androgens are responsible for development of pubic hair and some other pubertal changes. However, they have no role in activation of GnRH pulse generator. Once GnRH pulse generator becomes active, the gonads start producing testosterone or estrogen and rest of the pubertal changes occur. The gonadal hormones provide negative feed back to the GnRH pulse generator.

Hope this answers your query.

Best wishes.

Dr Preeti Parakh
MD Psychiatry
Above answer was peer-reviewed by
 
Follow-up: Puberty gonadotropins increase, and this increase is attributed to increase in amplitude. Mirrored preceding Gnrh secretion also? 2 days later
Thank you Dr XXXXXXX for great answer.

Just one final question if i may.

I understand that from mid-childhood to onset of puberty, pulse frequency of gonadotrophins doubles and amplitude also increases.

So if androgens doesnt help to develop this, what does?....Is it something exclusively neuronal and brain driven?

Wishing you all the best

Regards
 
 
Answered by Dr. Preeti Parakh 2 hours later
Brief Answer:
Yes, you are right.

Detailed Answer:
Hi Rony,

Thanks for writing back!

Yes, you are right. Some changes take place in the brain at puberty which increase the activity of the GnRH pulse generator. While the exact mechanism is not yet known, the following have been implicated.

1)Kisspeptins

In just the past few years, kisspeptins have emerged as a critical component of the system that controls the level of GnRH neuronal activity between infancy and puberty. Kisspeptins are neuropeptides and hypothalamic kisspeptin secretion is distinctly pulsatile and highly correlated with that of GnRH.

2) Leptin

Leptin is produced by adipocyte and has been implicated as one way in which metabolic signals might be communicated to the higher centers controlling the activity of the hypothalamic pulse generator at the onset of puberty. Leptin-deficient mice and rats fail to enter puberty, and treatment with leptin induces the onset of puberty. Similarly, children with malnutrition have delayed puberty probably because of this.

3) Glutamate

Glutamate is an excitatory neurotransmitter in the hypothalamus and has been shown to stimulate GnRH release in experiments.

4) Gamma-aminobutyric acid (GABA)

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter produced by specialized neurons in the hypothalamus and has an important role in regulating the activity of the GnRH pulse generator. It acts as a "neurobiologic brake" to restrict GnRH secretion till puberty occurs.

5) Neuropeptide Y (NPY)

Neuropeptide Y is a hypothalamic peptide involved in the control of food intake behavior and reproductive function in adults. It has been suggested that NPY, like GABA, is an important component of the “neurobiologic brake” that restrains the GnRH pulse generator in prepubertal age.

It is believed that these chemicals interact with each other and together are responsible for the increase of pulsatile GnRH secretion at the onset of puberty.

Hope this answers your query. Please feel free to ask if you need any other clarifications. I shall try to answer to the best of my capability. But if there are no more queries, then please close the discussion and rate it.

Best wishes.

Dr Preeti Parakh
MD Psychiatry
Above answer was peer-reviewed by
 
Share on Facebook
Share on Twitter
Share on Google+
Question is related to
Diseases and Conditions
Drug/Medication

The user accepted the expert's answer

Ask an Endocrinologist

© Ebix, Inc. All Rights Reserved.
All the information, content and live chat provided on the site is intended to be for informational purposes only, and not a substitute for professional or medical advice. You should always speak with your doctor before you follow anything that you read on this website. Any health question asked on this site will be visible to the people who browse this site. Hence, the user assumes the responsibility not to divulge any personally identifiable information in the question. Use of this site is subject to our Terms & Conditions
Already Rated.
Your rating:

Ask a Doctor