Secretin is a hormone produced by the small intestine that plays a key role in digestion. Disturbances in secretin levels can impact digestive processes. For instance, overproduction of secretin may lead to excessive bicarbonate secretion, causing alkaline diarrhea. On the other hand, deficiencies in secretin can result in impaired digestion and absorption of nutrients. Monitoring secretin levels is crucial for understanding and managing digestive disorders.

1. University of Chakwal, Pakistan

2. Topic: Disturbances in Secretin Hormone
Department of Zoology
Presented by: Mishaal Naseer
Roll no# UOC-BSZOL-F2020/002
BS Zoology
Session: 2020-2024
Subject: Endocrinology
Instructor Name: Dr. Syeda Nadia Ahmed

3. Introduction
Discovery
Functions
Disturbances

4. Introduction
▪ Secretin is a 27 amino acid peptide hormone.
▪ It is formed by S cells found in duodenum.
▪ Inactive form of secretin is “Prosecretin” that is activated
by gastric acid.
▪ Secretin stimulates pancreas; plasma membrane of
pancreatic centroacinar cells have secretin receptors
(Henriksen & Muckadell, 2000).

5. Discovery
In 1902, E.H. Starling discovered “Secretin” in
collaboration with W.M. Bayliss.
It was the first “Chemical Messenger” identified.
This type of a substance is now called a hormone, a term
coined by Bayliss in 1905 (Henriksen & Muckadell,
2000).

6. Functions
Secretin has three main functions:
❖Regulate pancreas to secrete pancreatic juices.
❖Regulate water balance in cells.
❖Regulate pH in small intestine by influencing gastric acid
and biocarbonate release (Chu et al., 2006).

7. Disturbances in Secretin Hormone
• Increased production of
pancreatic juice and bicarbonate
Overproduction
• Less release of pancreatic
enzymes and bile
• Impair digestion
Underproduction
• Receptor and secretin interaction
problems
• Digestive issues
Receptor
Sensitivity
Issues

8. Causative
Factors
Pancreatic Disorders
Small Intestinal
Disorders
Autoimmune
Disorders
Genetic Mutations
Medications and
Treatments
Infections
Tumors

9. Digestive Disorders
Secretin itself does not directly cause diseases, but abnormalities
in its function can lead to certain digestive disorders:
➢ Peptic Ulceration
➢ Cholestasis
➢ Zollinger-Ellison Syndrome
➢ Chronic Pancreatitis (Digregorio & Sharma, 2019).

10. Peptic Ulceration
It is secretin deficiency disease
caused by H. pylori infection.
Peptic ulcer is a hole or sore in
the lining of stomach, intestine,
oesophagus.
H. pylori infection increases
gastric secretion and reduces S-
cell population (Malfertheiner
et al., 2009).
Fig. 1.1: Peptic Ulceration
https://thegidocs.com/wp-
content/uploads/2022/12/img29-1.png

11. Cholestasis
Cholestasis is a liver disease. It is
due to increased quantity of
secretin receptors.
Increased secretin secretion leads to
increased bile duct cell growth and
eventually liver damage. Flow of
bile from liver is reduced or
blocked (Elferink, 2003).
Fig. 1.2: Cholestatic Liver Damage
https://www.opioidtreatment.net/wp-
content/uploads/2018/02/liver-
damage.jpg

12. Zollinger-Ellison Syndrome
Gastrinomas, the tumors grow in
pancreas or in the upper part of small
intestine. These tumors produce large
amount of hormone gastrin.
Gastrin level is stimulated by secretin
which stimulates the G cells directly
and at same time inhibit G cell
indirectly by stimulating somatostatin
secretion (Hung et al., 2003).
Fig. 1.3: Zollinger-Ellison Syndrome
https://th.bing.com/th/id/R.d423d913df
6fe7062ec811cf534a0205?rik=s4r8eIc

13. Chronic Pancreatitis
It is a inflammation of pancreas.
Prolonged inflammation leads to
structural changes in pancreas.
This disrupts the normal response
to secretin, influencing enzyme
release and impairing digestion
(Braganza et al., 2011).
Fig. 1.4: Chronic Pancreatitis
https://pocketdrugguide.com/wp-
content/uploads/2018/11/chronic-
pancreatitis-1.jpg

14. Social Behavior
Secretin deficient mice show reduced hippocampal
function and social behavior because secretin acts as a
neurotransmitter in the brain.
Secretin also increase oxytocin release in the brain,
increased social behavior in rats (Nishijima et al.,
2006).

15. Secretin Stimulation Test
This test is used to diagnose pancreas disorders and
diseases. It is a measurement of the ability of pancreas in
response to secretin.
In this test, patient receives secretin through nose or throat
via a tube. After 1-2 hours, blood levels of pancreatic
secretions are elevated.
Abnormal level of pancreatic secretions tell that there are
problems in the pancreas (Madhavan, 2020).

16. References
Chatzipanagiotou, O., Schizas, D., Vailas, M., Tsoli, M., Sakarellos, P., Sotiropoulou, M. &
Felekouras, E. (2023). All you need to know about gastrinoma today| Gastrinoma and
Zollinger‐Ellison syndrome: A thorough update
Madhavan, P., Aftab, H., & Tendler, B. (2020). SAT-121 Secretin Stimulation Test in a Patient
Receiving Proton PUMP Inhibitor Therapy-to Do or Not to Do?. Journal of the Endocrine
Society, 4(Supplement_1), SAT-121.Journal of Neuroendocrinology, 35(4), e13267.