Smell and the Brain Odorous substances, including plant-derived fragrances,

induce various physiological, emotional, and behavioural responses in human and other mammalian species

Smell and the Brain Neuronal impulses conduct along the olfactory tract

to: prepiriform cortex, limbic system, thalamus and much more

Complex interconnected networks are responsible for many behaviours:

eating, affective, sexual and reflexes like salivation (trigeminal n.)

Plant Derived Chemicals Have long been utilised as holistic relaxants in

aromatherapy and complementary medicine

Only recently have their physiological mechanisms been investigated

PraescentTM alpha-pinenetrans-2-hexenalcis-3-hexen-1-ol

Presented by Aaron Sparshott

Alleviating Effects of Plant-Derived Fragrances on Stress-Induced

Hyperthermia in Rats

By Akutsu et al

Introduction Investigated the effects of exposure to plant-derived

odours on the autonomic and behavioural responses to novel environment in rats.

A transient increase of body temperature has been shown to be a typical and reproducible autonomic response to various physical as well as psychological stressors.

This response is often referred to as stress induced hyperthermia or emotional fever.

What they did... Rats were moved to a novel environment, by being

transferred to an unfamiliar cage with a certain odour present.

42 Rats in Total: Alpha-pinene, Lavender and Green Odour cages were each presented with 12 rats. Control Group rats were placed back in original cage after handling.

Half of each odour group (n=6) except control, were exposed to solvent only.

12 12 12 6

Biosignals and Behaviour Heart Rate and Temperature were monitored using a bio-

signal transmitter implanted a week prior to experimentation.

Behavioural Analysis via video camera. Sniffing Rearing Grooming Resting General Activity

What they discovered... Green Odour

accelerated the declining phase of body temperature

Alpha-pinene suppressed stress-induced hyperthermia from the beginning

T i m e (min)

Tem

pe

ratu

re D

iffe

ren

ce (

oC

)

What they discovered... Exposure to any of the three fragrances made no

significant difference to Heart Rate

T i m e (min)

∆ B

PM

No significant differences in behaviour were observed as a result of any fragrance

What does it mean? Body Temperature rose as a result of being moved to a

novel environment, reflected as a stress-induced hyperthermia response.

Previous studies have shown that stress-induced hyperthermia responses can be attenuated by pretreating the subject with centrally acting drugs such as; noradrenaline β receptor antagonist, vasopressin, prostaglandin inhibitors 5-HT1A receptor agonists

What does it mean? In the present study, the rats were exposed to odorants

without being given any severe stress, and the exposure to the green odour or the alpha-pinene was found to have alleviating effects of the stress-induced hyperthermia.

However it would appear that the mechanism of alleviation differs between the two odours.

Other points of interest Heart Rate might be a less sensitive parameter as compared

with the Body Temperature for detecting the possible alleviating effects of fragrances on stress responses

‘Sedative effects’ of lavender in human’s are more likely to be a psychological property rather than physiological. Autonomic responses showed no significant difference to control

No observed change in behaviour.

Summing UpBy recording autonomic and behavioural

parameters from unrestrained rats, Akutsu et al found that the

green odour and alpha-pinene have anti-stress potency, namely that they exerted alleviating effects on stress-induced

hyperthermia.

Presented by Zoe Hutchins

Attenuation of Stress-Induced Elevations in Plasma ACTH Level and Body Temperature in Rats by

Green Odour

By Nakashima et al

Introduction Investigated the effect of green odour on plasma

adenocorticotropic hormone (ATCH) and body

temperature (Tb) of stress-induced rats

GREEN ODOURtrans-2-hexanal [0.03%]

cis-3-hexenal [0.03%]

↓ Tb↓ACTH

Hypothalamus

Olfa

ctor

y In

puts

Anterior Pituitary

Preoptic Centre

Stress Response:Elevation of ACTH Level and Tb

Rats were relocated and immobilised via restraint for 2 hours

Control: immobilisation without green odour

Treatment: exposure to green odour at various times prior, during or following immobilisation

Blood was collected and assayed for ACTH either immediately following immobilisation or 2 days later.

STRESS

1h 1h½ h 0h 2h 4h 6h 48h

Immediate ACTH Long-Lasting ACTH

Method - ACTH Measurements

Green odour [0.03%] decreased ACTH levels when applied during or following immobilisation.

Results – ACTH Levels

Rats were implanted with telemetry transmitters and given 10 days to recover until ACTH levels stabilised.

Tb was recorded every 20 minutes for 3 consecutive days.

Treatment rats were exposed to green odour for 30 minutes during the beginning of the 2 hour immobilisation.

Device Implantation

10 daysRecovery

Day 1(Prior)

Day 3(Post)

Green Odour (½hr)

Stress (2hr)

Temperature Recording

Method – Tb Measurements

Green odour [0.03%] decreased Tb immediately after stress and during the light phase of the following day.

Results – Tb Recording

During immobilisation the odorous paper was held 3cm from the nose of the rat, however when applied before or after immobilisation, the paper was placed in a corner of the cage.

Potential inconsistencies in the levels of green odour exposure the different groups received.

IMMOBILISED NON - IMMOBILISED

Methods - Weaknesses

Immediately following stress & two days post-stress

When applied during or following stress

Results Summary

GREEN ODOUR

↓ ACTH↓ Tb

ACTH Levels Hypothalamus & Catecholamine System ↓ Fos in the Paraventricular Nucleus (PVN) down-

regulating CRH secretion and subsequently ACTH Tb Reduction

↓ Sympathetic activity ↓ ACTH and Glucocorticoids

Further research is required to fully elucidate the physiologic mechanisms of green odour

Possible Mechanisms of Action

Due to current unpublished work the remainder of this presentation is not available to slideshare.

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