Pituitary Stalk Transection Question

[BMW M3]

A couple of questions:

1) Where exactly is the dopamine control for the release of prolactin (up in neuron cell bodies or down at the axon terminals)?

2) If the pituitary stalk is transected are ALL the hormones of the ANTERIOR and POSTERIOR pituitary decreased?

3) Would diabetes insipidus be expected?

I ask this because I am confused by the conclusions in this article (can anyone explain that pathophysiology of this finding?): http://www.ncbi.nlm.nih.gov/pubmed/6766537

Prolactin levels rose rapidly and remained significantly elevated in all effectively stalk-sectioned animals

As always, thanks in advance!!!

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[agranulocytosis]

Yeah I had the same question. I was stuck between 2 answer choices in a certain NBME form (forgot which one). I ended up going with the logic that with a transection the pituitary cells are all dead. But I do know that ADH is synthesized in the hypothalamus and there is some residual effect of ADH due to it's release from the hypothalamus in a transection of the stalk. Now if there was a mass impinging on the stalk, then I'd say prolactin would increase.

That abstract says "section" and not transection, so I'm not sure what that really means.

 

[alpha06]

That abstract says "section" and not transection, so I'm not sure what that really means.

Like section or a piece of the stalk whereas transection is cut all the way through.

1) Where exactly is the dopamine control for the release of prolactin (up in neuron cell bodies or down at the axon terminals)?

Well I'm thinking DOP is released from the hypothalamus and has its action on PRL in the pituitary.

2) If the pituitary stalk is transected are ALL the hormones of the ANTERIOR and POSTERIOR pituitary decreased?

No, because you have the stalk from the hypothalamus to pituitary which still can release ADH. And maybe oxytocin too....

3) Would diabetes insipidus be expected?

Not to a great degree since you have some ADH being secreted from the stalk.

 

[DrFraud]

A couple of questions:

1) Where exactly is the dopamine control for the release of prolactin (up in neuron cell bodies or down at the axon terminals)?

2) If the pituitary stalk is transected are ALL the hormones of the ANTERIOR and POSTERIOR pituitary decreased?
3) Would diabetes insipidus be expected?

I ask this because I am confused by the conclusions in this article (can anyone explain that pathophysiology of this finding?): http://www.ncbi.nlm.nih.gov/pubmed/6766537


As always, thanks in advance!!!

Very good question about the ADH. ADH is made in the hypothalmus, and so if you damaged the hypthalamic nuclii where the cells make ADH, you would get persistent central diabetes insipidus. If you damaged the stalk, you would only get a transient diabetes insipidus since some of the ADH will make it to your blood stream from the damaged pituitary stalk. I guess this also answers your second question too.....My source for this isn't perfect, but it's been fairly reliable for me - UsmleW

 

[BMW M3]

2) If the pituitary stalk is transected are ALL the hormones of the ANTERIOR and POSTERIOR pituitary decreased?

No, because you have the stalk from the hypothalamus to pituitary which still can release ADH. And maybe oxytocin too....

Aren't these stalks one in the same? A transection through the pituitary stalk should take out BOTH the anterior and posterior pituitary connections to the hypothalamus. No?

 

[DrFraud]

Aren't these stalks one in the same? A transection through the pituitary stalk should take out BOTH the anterior and posterior pituitary connections to the hypothalamus. No?

-Please see my response above.

 

[BMW M3]

-Please see my response above.

ah sorry.. simutaneous post.

what about prolactin? will that be elevated?

 

[DrFraud]

ah sorry.. simutaneous post.

what about prolactin? will that be elevated?

Ok, I know this is bad because I would like to believe that my memory from basic sciences was more than just remembered TQs, but I remember seeing a question where a young man who was involved in an auto accident that had galactorrhea/infertility due to a ruptured or compressed pituitary stalk(as well as other endocrine symptoms)

 

[penguinophile]

ah sorry.. simutaneous post.

what about prolactin? will that be elevated?

Yup, you lose the dopamine blockage that keeps prolactin levels low due to the stalk loss.

One thing that always bothered me about these types of problems was the situations when there was trauma and a complete transection vs. Sheehan's which is apparently infarction of the anterior pituitary.