Effect of inflammation and anesthesia on brain-derived neurotrophic factor and cognition
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ANAESTHESIA, PAIN & INTENSIVE CARE
www.apicareonline.com
ORIGINAL ARTICLE
Effect of inflammation and anesthesia
on brain-derived neurotrophic factor
and cognition
Muhammad Rafiq, PhD1,2 Laure Pain, MD2,
Naseem Ahmed, MCPS, FCPS3
ABSTRACT
1
Institute of Clinical Psychology, Background: Some studies have evidenced the effect of inflammation and anesthetics
University of Management and on Brain Derived Neurotrophic Factor (BDNF) but there is still no data regarding the
Technology, Lahore, Pakistan. effect of inflammation and anesthesia alone or in combination of inflammation and
2
CNRS, Unit UPR-3212, anesthesia on BDNF protein in rats’ brain.
Neurobiology of Rhythms,
University of Strasbourg, Objectives: To examine effect of lipopolysaccharides (LPS) alone or combined with
Strasbourg, France. propofol anesthesia at 3rd of injection on cortical and hippocampal BDNF.
3
Consultant Anesthesiologist,
Combined Military Hospital, Methodology: Male rats in four groups were treated with Intralipid® control, propofol
Rawalpindi (Pakistan) anesthesia (120 mg/kg), LPS (1 mg/kg) and combined propofol with LPS respectively.
The brains were removed and brain homogenates were prepared from hippocampus
Correspondence:
and cortex tissues. The amount of BDNF protein was assessed using ELISA on the brain
C-II, Institute of Clinical
supernatants.
Psychology, University of
Management and Technology Results: BDNF protein was increased when subjects were injected with propofol
(UMT), C-II, Johar Town, Lahore
anesthesia alone (about 30%) or to LPS injection (about 400%) in both cortex and
(Pakistan); E-mail:
hippocampus samples. When anesthesia was injected combined with LPS, BDNF protein
rafiqdar@hotmail.com;
muhammad.rafiq@umt.edu.pk; was decreased in both cortex and hippocampus samples (p < 0.01).
Phone: 03213330471
Conclusion: Our data evidenced the long term effect of propofol and LPS in increasing
Received: 14 Jul 2018 BDNF and propofol combined with LPS decreases BDNF protein in hippocampus and
Reviewed: cortex.
31 Jul, 15 Aug, 27 Aug 2018
Revised: 1 Aug 2018, Key words: Lipopolysaccharide; BDNF Protein; Anesthesia; Propofol; Cortex;
Accepted: 01 Sep 2018 Hippocampus; Inflammation; Cognition
Citation: Rafiq M, Pain L, Ahmed N. Effect of inflammation and anesthesia on brain-
derived neurotrophic factor and cognition. Anaesth Pain & Intensive Care 2018;22(3):
318-322
INTRODUCTION physiological processes are protected by the special
proteins in the brain called neurotrophic factors. As
Lipopolysaccharide (LPS), a potent bacterial
neurotrophins are involved in the protection against
inflammatory endotoxin involved in neural responses
many insults to the brain anatomy and physiology,4)
and has been implicated in cognitive deficits through
and have been implicated in learning and memory
the activation of immune system.1 Studies have
processes.5
indicated that injections of LPS led to the reduction
of neurogenesis and increases in the process of Studies on laboratory animals have shown that LPS
apoptosis.2,3 Literature has shown that stimulation of may be responsible for alteration of neurotrophic
immune system by the LPS may damage the brain factors and their functions in brain areas including
physiological processes and this dysfunction in the hippocampus.6 Study on mice synaptosomes has
318 ANAESTH, PAIN & INTENSIVE CARE; VOL 22(3) JUL-SEP 2018brain-derived neurotrophic factor and cognition
shown reduction of brain-derived neurotrophic factor extracted and cortex and hippocampal structures
(BDNF) within 1-6 days post LPS injections and were separated on ice. Cortical and hippocampal
maximum reduction at day 3.7 However, a study on tissues were homogenized in extraction buffer. After
dendritic cells has shown increased levels of BDNF centrifugation step (4000 rpm, 20 min), supernatants
LPS has also shown an up-regulation of BDNF in the were extracted and stored at -20º C. BDNF protein was
dendritic cells generated from donors and measured measured by ELISA technique (CYT306, Millipore)
by western blot, PCR and flow cytometry.8 according to manufacturer’s guidelines.10-12
In addition to LPS, anesthetics have also been
RESULTS
implicated in alteration of BDNF in important brain
areas: cerebral cortex and thalamus.9 Thalamus has We quantified an increase of the BDNF protein when
shown reduction of BDNF protein at 2 hours post subjects were injected with propofol (about 30 %) and
injection of general anesthesia in developing brain, LPS injection (about 400 %) in both cortex (Figure
however cerebral cortex showed increase of BDNF at 1) and hippocampus samples (Figure 2). When
2 and 6 hours.9 anesthesia was combined with LPS injection, we
observed of decrease of BDNF content as compared to
There is not too much data regarding the effect of LPS
LPS injection alone in both cortex and hippocampus
with/without short duration anesthesia on BDNF
samples. Multivariate ANOVA (between factors:
in brain especially in cortex and hippocampus. The
anesthesia, LPS and within factors: structure)
above studies suggest some questions to be answered;
revealed significant effects of anesthesia (Intralipid
like is there any long lasting effect of LPS with/
control or propofol; F(1,28) = 19 ; p = 0.0001), and
without short duration anesthesia on BDNF protein
LPS injection (saline or LPS ; F(1,28) = 412 , p <
in brain of adult rat. So, the current study was aimed
10-4), in structures (cortex vs. hippocampus; F(1,28)
to evaluate impact of inflammation and anesthesia
=17; p = 0.0002) and significant effect between
on cognition by quantifying BDNF protein in
anesthesia and LPS (F(1,28) = 40; p < 10-4) and
the hippocampus and cortical areas at 3rd day of
between structure and LPS (F(1,6) = 6 ; p = 0.0181)
treatment at ZT5 (Zeitgeber Time 5). ZT5 means 5
on the BDNF protein.
hours after light on, and this time point have shown
peak of BDNF in unpublished data. So, the current Post hoc analysis indicated that subjects injected with
study was focused to examine any inflammatory and propofol anesthesia or LPS differed significantly from
anesthetic effect on BDNF protein at its peak. the controls groups in both hippocampal and cortical
structures (all p < 0.01). There is also a significant
METHODOLOGY decrease of BDNF content in animals submitted to
the combined anesthesia and LPS regimen compared
Animals: Young male rats (Sprague Dawley) of 8-10
to animals receiving LPS injection without anesthesia
weeks (250 ± 20 g) were housed 5-6 per cage for seven
days in a temperature (22 ± 1ºC) and
humidity (50 ± 10%) on 12/12/ light/
dark cycle. All subjects were provided
ad libitum access to food and water.
Treatment: All experimental animals
were divided into four groups and
eights subjects were included in
each group. Subjects of all the four
groups were injected intra-peritoneal
at ZT10 with propofol (120 mg/kg,
Fresenius, France) with same dose of
Intralipid® 20% (Fresenius, France)
as control, LPS from E.coli (1 mg/kg,
Sigma USA) and LPS plus propofol
respectively.
Procedures: On next day of
injections, subjects in each group were
sacrificed at ZT5 after euthanasia Figure 1: Graph represents percentage change in BDNF protein in cortex
of subjects treated with LPS, propofol anezsthesia and LPS with propofol
under CO2. The brain tissues were anesthesia with their Intralipid control
319 ANAESTH, PAIN & INTENSIVE CARE; VOL 22(3) JUL-SEP 2018brain-derived neurotrophic factor and cognition
protection and neuroplasticity.16
Another study showed protective
effect of exogenous BDNF in rats
with experimental meningitis.17
But our data differs from the study of
Guan and Fang that showed reduction
of BDNF in hippocampus after intra-
peritoneal injections of LPS.18 This
reduction in BDNF may be due that
the proteins were quantified few
hours after injects of LPS.
It is noted that anesthetics have
been responsible in the alteration
of BDNF in brain areas including
cerebral cortex and thalamus.9
Usually anesthesia is associated with
Figure 2: Graph represents percentage change in BDNF protein in
hippocampus of subjects treated with LPS, propofol anesthesia and LPS with
surgery, 24 hours after surgery under
propofol anesthesia with their Intralipid control propofol anesthesia shows a decrease
in plasma BDNF concentrations in
in both cortical and hippocampal structures (all p < patients.19 In rats, BDNF protein is
0.01). also decreased 24 hour after tibia fracture performed
under anesthesia.20 This may reflect immediate effect
DISCUSSION of anesthetics in reducing the levels of BDNF protein.
The current study showed the effect of propofol Our current study may differ in way that we
(short duration anesthesia) and LPS (E.coli) on conducted quantified BDNF protein ex vivo at ZT5
BDNF protein in the cortex and hippocampal of and quantified BDNF protein at 3rd day of treatments
the rats. Animal groups were injected at ZT10 with with LPS, propofol, and propofol with anesthesia.
propofol (120 mg/kg), LPS (1 mg/kg), combined However, combination of LPS with anesthesia
propofol and LPS and Intralipid as control. Brains showed a decrease in levels of BDNF proteins in
were removed on ice at ZT5 (time of peak BDNF both the structures i.e. cortex and hippocampus. This
protein expression). This specific time point was may suggest a protective effect of propofol against
chosen to standardize the data, as studies have the damage caused by over production of BDNF due
suggested that proteins vary during different time to LPS. As over production of BDNF has been also
of the day.13 The BDNF protein was measured using shown detrimental in the process of learning and
ELIZA technique for both hippocampus and cortex memory.21 These detrimental effects of overexpression
homogenates. ELISA has been evidenced suitable, of BDNF protein due to anesthesia and LPS may be
specific and sensitive method for the measurement of noted by performing the behavioral experiments in
antigens in tissue and blood sample.14,15 rats. These results show BDNF alterations may be
Our results indicated that the level of BDNF protein due to circadian effect, so there is need to quantify
was increased in both structures’ homogenates: the BDNF at few other time points during 24 hours.
cortex and hippocampus when subjects were either Our results focus on short during anesthetcis, so we
treated with propofol anesthesia (about 30 %) or LPS cannot conclude for other type of anesthetics.
(about 400 %). We observed a decrease of BDNF Strengths of the study: This study shows the
protein contents when anesthesia was combined with effect of short during anesthesia on Brain Derived
LPS injection as compared to LPS injection alone in Neurotrophic Factor.
both cortex and hippocampus samples. Our results
Weaknesses of the study: The limitation of the
may suggest that there is a damaging effect of LPS
study is that effect is limited to short anesthetics and
even at day 3 that is shown by an increase of BDNF.
we cannot conclude for long term anesthetics
Our results also show that there may be a protective
effect of propofol against the damage caused by LPS Statement on ethical standards
by lowering the over elevated levels of BDNF, as All the procedures were performed at Unit UPR-
BDNF is evidenced as major mediator of neuronal 3212 CNRS, Strasbourg University, France. All
320 ANAESTH, PAIN & INTENSIVE CARE; VOL 22(3) JUL-SEP 2018brain-derived neurotrophic factor and cognition
procedures on laboratory animals were performed in Authors declare no conflict of interest
compliance with national (Ministère de l’Agriculture Authors’ contribution:
et de la Forêt, Service Vétérinaire de la Santé et de
MR-Concept, experiments, writing
la Protection Animale;) and international guidelines
(NIH publication, no. 86-23, revised 1985). LP-Concept, manuscript editing
Conflict of interest NA-Manuscript editing, review
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My Most Memorable Patient
The case of subarachnoid hemorrhage
Dr. Mariam Saghir
Specialty Doctor, Accident and Emergency, Heartlands Hospital, Birmingham,
Green East b95ss. (UK); E-mail: mariamsaghir13@gmail.com
I went through his past medical records,
medications and observations. He had had
subarachnoid hemorrhage twice and had been
on warfarin. As there was no indication for
CT scan I thought there was nothing to worry
about. I again asked the patient if he recalled
his morning conversation. He stated he didn’t
but he did suffer from memory loss. The fact
that the relatives had genuinely felt a need
to bring this well-dressed gentleman to the
hospital warranted that he must not be ignored.
One of the key things while working in an I requested a CT scan, stating amnesia. I had a
acute specialty is the occasional weird and row with the radiologist to get him scanned. The
wonderful experience that may not fit in the patient mocked me about being overly cautious
normal emergency textbook stories. Such a case and walked towards the scanner. Fifteen minutes
I encountered while working as a senior house later while I was writing my notes up I heard my
officer at Birmingham Heartlands Hospital. name on the speakerphone across A&E to come
A gentleman in his early seventies presented on to radiology. I ran towards the resuscitation unit
a cold winter evening to the minor section of to find my patient a bit puzzled but alert. The
A&E with his sister-in-law complaining of a mild patient had a massive subarachnoid hemorrhage
headache rating 4/10. He stated that it was not with a midline shift. The registrar was amazed
the first headache of his life and laughed as if his as to how a patient was completely stable with a
sister-in-law had brought him and made him wait GCS 15. Having a look at those scans made me
her for 3 hours to see a doctor just for nothing. realize I close was I to sending this patient home,
I took a detailed history and examined him and who would have most likely come back collapsed.
relayed my information to my consultant. As the The patient was quickly transferred to the nearest
patient looked completely fine I wanted to send
neurosurgical unit and an urgent drainage done.
him home but just as I was about to write up my
plan, I felt that his sister-in-law must have some To this day I have reflected from this case and
concern that warranted this trip. She stated that made sure to always add one more portion to my
he had been fine but while talking to her in the history taking: ‘any concerns by the family’ -
morning he narrated in one line about his role in this helps you to pick up those rare presentations
world war two, which was quite out of context. that could have been so easily missed.
322 ANAESTH, PAIN & INTENSIVE CARE; VOL 22(3) JUL-SEP 2018You can also read
