Pak. J. Biochem. Mol. Biol. 2010; 43(2): 105-108
Exposure to illuminated salt lamp increases 5-HT metabolism: A serotonergic
perspective to its beneficial effects
Hajra Naz* and Darakhshan J Haleem
Neurochemistry and Biochemical Neuropharmacology Research Unit, Department of Biochemistry,
University of Karachi, Karachi, Pakistan
Abstract: For centuries people have known the ability of salt rock crystal to improve air qualities by enriching it with negative ions. Salt
lamps are thought to be a good source of negative ions. In view of the claim of the salt lamp sellers regarding its beneficial effects the
neurochemical study was an extension of the behavioral study conducted in rats. Test animals were exposed to salt lamp for 14 weeks.
Decapitation after 14 weeks, followed by neurochemical analysis showed that brain tryptophan and 5-HT metabolism were increased after
salt lamp exposure. The results are discussed in relevance to its antidepressant effects and other behavioral activities monitored previously.
Keywords: Illuminated salt lamp, 5-HT metabolism, brain tryptophan, serotonin.
Received: January 12, 2010 Accepted: April 27, 2010
*Author Correspondence: Hajra20052005@yahoo.com
Previous studies have shown that exposure to
salt lamp enhances memory, lessens anxiety and
improves activity 1 in animal models. The sellers
of salt lamp claim that the negative ions produced
from salt lamp (which is one of its proposed
mechanism) could be recommended for their
beneficial effects in enhancing immunity, increased
alertness, increased work productivity, increased
lung capacity, and reduced susceptibility to colds
and flu. The present study was designed to
investigate the serotonergic mechanisms involved
in the previously published data1.
It is a common observation that people
develop feelings of pleasantness and well-being
after storm, when the environment is clean and
fresh; filled with abundant negative ions. Studies
have shown that novel purification systems using
positively and negatively charged ions were
developed to create comfortable living
environments2. A balance of negative and positive
ions is essential for healthy living. Various natural
and environmental factors such as hot and dry
winds, pollution, TV screens and many other
human activities produce positive ions which
create an imbalance of these ions3. Salt crystal
lamps have properties, enhancing on health and
well-being. It is said that they emit ions. The
negative ions are generated by a continuous
interplay of water attraction and evaporation. The
salt crystal lamp attracts water molecules from the
surrounding air to its warm surface. The water and
salt form a solution. In the process of evaporation
of the solution, due to the heat of the lamp,
negatively charged ions are created. Both positive
and negative ions are created but much more
negative ions than positive ions are created,
therefore providing a surplus of negative ions.
Natrium is positively charged. This unique ion
emission interplay ability with water is because of
salts neutral atomic structure.
Scientific research clearly points out that a
balanced ratio between negative and positive ions
in the air we breathe affects our well-being. From
this study warm Salt Crystal lamps can be seen to
be the natural ion generators. The efficacy of
negative ions has been also well-proven from
previous and current research mentioned below.
Negative ions exert bactericidal effects on
staphylococcus albus4. Hydrated negative ions
emitted from air-cleaning devices such as plasma
generators have also known to produce bactericidal
effects5. Biocidal effects have also been
demonstrated by Marin and his coworkers6 on
gram positive and gram negative bacteria.
Treatment with negative ions has shown
remarkable diminution in the allergen against
Japanese cedar pollen allergies 2. Studies have been
also focusing on health benefits of speleotherapy
for chronic congestive problems in salt mines.
Studies conducted in Russia have demonstrated
speleotherapy courses noticeably diminish
broncho-obstructive syndrome and improved
ventilation of pediatric asthmatics7. Courses of
speleotherapy in the microclimatic conditions of
salt mines have shown to increase the number and
functional activity of T-lymphocytes, while
normalization of B-lymphocytes resulting in
alleviating bronchial asthma attacks8. Equally
important as the ionizing effect, is the Salt crystal
lamps’ ability to neutralize and purify air.
Depending on the size and the surface area of Salt
Crystal lamp the purification of surrounding air
takes place during the transformation cycle in
water attraction and evaporation, involving
hydrogen and oxygen, as well as sodium and
chloride, resulting in significant purification of air.
This property will greatly benefit asthma and
allergy sufferers. Apart from the natural ionization
Naz and Haleem
of salt lamps, it could also harmonize and enhance
our system and functions by electromagnetic
radiations and color therapy.
MATERIALS AND METHODS
The experiment was conducted on 24 male
rats. The animals were randomly divided into
controls and salt lamp exposed group. Animals
assigned to experimental group were exposed to 8
salt lamps purchased from Java food International,
Clifton, Karachi, Pakistan, were kept in a small
room (10x8x10) ft. The lamps were left on for 24 h
for a period of 14 weeks. Lamp bulbs were
replaced immediately if they were fused so as to
ensure that the rats were exposed uninterruptedly
to the illuminated lamps. Their counter parts were
also housed individually and placed in a room
devoid of salt lamps so as to provide them with a
The animals were decapitated after the 14th
week by cervical dislocation plasma and brains
were stored at -70°C for neurochemical analysis.
The ethical conditions were maintained throughout
Removal of brain from cranial cavity
After decapitation the skin was cut with the
help of scissors. A long incision was made with the
help of scissors and the two halves of the skull
were separated. The connections were loosened
and the brain was taken out from the cranial cavity
and placed on the glass plate.
Extraction of TRP from plasma
To 0.01 ml of plasma, 0.2 ml of 0.4M
perchlorate containing 0.1% sodium
metabisulphate, 0.01% EDTA and 0.1% cystine
was added and thoroughly mixed. The mixture was
then centrifuged at 12,000 rpm for 10-15 min at
4oC in Eppendorf tubes. Supernatants were then
used for determination of TRP by HPLC.
HPLC-EC determination of tryptophan, 5-HT
Tryptophan, 5-HT and 5-HIAA from brain
samples were extracted as described previously 9.
A 5µ ODS separation column 4.0 mm and 250 mm
length was used. Mobile phase comprised
methanol (14%), octyl sulphate (0.023 %) and
EDTA (.0035%) in 0.1 M phosphate buffer at pH
2.9 was passed through the column at an operating
pressure of 2000-3000 psi with the help of Waters
510 HPLC pump. Electrochemical detection was
achieved on Shimadzu- L –EC 6A detector at an
operating potential of 0.8 V. Tryptophan was
detected in a separate run at an operating potential
of 1.0 V.
RESULTS AND DISCUSSION
Figure 1 shows the effects of salt lamp
exposure on plasma TRP (a) and brain TRP (b) in
rats. Data analysed by t test showed increases in
plasma TRP (a) (P<0.05) and brain TRP (b)
Figure 2 shows the effects of salt lamp
exposure on brain 5-HT (a), brain 5-HIAA (b) and
turn over ratio (c) in rats. Data analyzed by t-test
showed decreases in 5-HT (P<0.05), increases in 5-
HIAA (P<0.05) and a significant turn over ratio
Figure 1: Effects of salt lamp exposure (14 weeks) on plasma
tryptophan (a) and brain tryptophan (b).
Previous studies have demonstrated that
serotonin plays a pivotal role in the modulation of
anxiety and depression related traits, as well as in
the pathogenesis of anxiety related disorders and
depression10, 11. Many studies converge to a point
that increasing 5-HT function is antidepressant12-14.
Our results demonstrate that 5-HT metabolism was
increased in animals exposed to salt lamp (Figure 2
2). The above findings could thus suggest that
exposure to salt lamp could be used to relief
depressive symptomatology. Animals exposed to
salt lamp exhibited increased plasma TRP (Figure
5-HT metabolism and salt lamp
1a) concentrations which could have increased due
to a decrease in TRP pyrrolase activity, thus
providing a greater availability of TRP to the brain
as seen in the present study (Figure 1b).
Figure 2: Effects of salt lamp exposure (14 weeks) on brain 5-
HT (a), brain 5-HIAA (b) and turnover ratio (c).
TRP being the precursor of 5-HT, can
modulate the synthesis of 5-HT as the enzyme TRP
hydroxylase which is confined to the serotonergic
neurons15,16 and catalyzes the rate limiting step of
5-HT synthesis is not saturated with the substrate at
normal brain TRP concentrations. Thus an increase
in TRP concentration in the plasma could have
increased the competition of TRP with other large
neutral amino acids; hence increased uptake of
TRP by the serotonergic neurons17 resulting in
increased 5-HT synthesis. However in the present
study 5-HT synthesis decreased, although plasma
and brain TRP concentrations increased in rats
exposed to salt lamp. These decreases of 5-HT
could be explained in terms of increased 5-HT
metabolism as evident from increased 5-HIAA
(Figure 2b) concentrations and increased turnover
ratio (Figure 2c). Thus the present study suggests
that enhanced degradation of 5-HT by monoamine
oxidases could have occurred in animals exposed
to salt lamp depending upon its concentration in
the plasma and brain.
Increased 5-HT metabolism is suggested to
improve cognitive performance18 where as
decreasing 5-HT levels have shown to impair
cognition19. Haider and co-workers20 from our
laboratory have demonstrated that long term TRP
administration enhances cognitive performance and
increases 5-HT metabolism. Our results
compliment the previously published1 data
reporting improved memory as assessed in RAM.
Enhanced cognitive performance in rats could be
due to increased TRP availability to the brain and
increased 5-HT metabolism as observed in the
previously published1 study.
Increased activity of animals was observed in
animals exposed to salt lamp. Increased in activity
is difficult to explain in terms increased 5-HT
metabolism because increasing 5-H T decreases
activity. It is possible that increased activity might
have occurred via another mechanism. One
possible explanation could be on the basis of
serotonergic Dopaminergic interaction of neurons
at the level of caudate to control motor activity 21.
5-HT acts via 5-HT-2C receptors on the DA
neurons to decrease motor activity22,23. Stimulation
of somatodendritic 5-HT receptors by enhanced 5-
HT turnover in raphe region could decrease the
availability of 5-HT in the caudate, releasing DA
neurons from the inhibitory effects of 5-HT and
elicit hyperactivity. It is therefore possible that
exposure of animals to salt lamp largely increases
brain 5-HT metabolism (5-HT metabolism
increased in whole brain) in the somatodendritic
region to decrease the availability of 5-HT at DA
neurons and elicit improved activity.
The present study also shows a fearless
response of the animals to the novel environment
of the light/ dark box and height plus openness of
the elevated plus maze thus helping us to suggest
that salt lamp exposure might produce anxiolytic
effect. The anxiolytic effects however cannot be
explained on the basis of increasing 5-HT
metabolism as observed in the present study
because decreasing 5-HT functions are anxiolytic
10. It is possible that salt lamp elicits a fearless
response in the above experiments via some other
Naz and Haleem
We suggest that usage of salt lamp might be
helpful environmental tool to relieve anxiety,
improve memory 1. Its anti-depressant effects
could be secondarily responsible to improve
activity in the activity box. Figure 3 shows a
proposed mechanism of action of the beneficial
effects of salt lamp environment.
Figure 3: Proposed mechanism of action of the beneficial
effects of salt lamp environment.
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