ABSTRACT

Stress is a prime factor for most of the illnesses in human life. Chronic stress exposure has

been reported to cause anatomical and physiological brain damage, immunosuppression,

infertility and damage to various internal organs. The function of stress hormones;

corticosterone and epinephrine is believed to preserve homeostasis but these hormones may

turn out to be detrimental in excess or if they persist in blood when no more required. Thirty

(30) Adult wistar rats of both sexes (n=30), weighing 150-200 g were divided into 3 groups

each consisting of a male and female subgroup and given the following treatments once a day

for 21 days: Normal control group received 1 ml distilled water orally, the restraint stress

(RS) group were exposed to chronic restraint stress 6 hours daily while the Apple cider

vinegar (ACV)-treated group received 4 ml/kg of apple cider vinegar orally in addition to

chronic restraint stress 6 hours daily. The rats were sacrificed after the experimental period

and blood was collected via cardiac puncture and the sera obtained and used for

determination of serum level of Corticosterone and Epinephrine as well as Malondialdehyde,

Superoxide Dismutase and Catalase activity. Preliminary phytochemical screening on apple

cider vinegar gave positive tests for flavonoids, anthraquinones, sterols and triterpenoids as

well as tannins. ACV (4ml/kg) showed adaptogenic activity by attenuating lipid peroxidation

(p<0.05) i.e decreased serum malondialdehyde level (655.52 nmol/mg of protein and 492.92

nmol/mg of protein in the male and female rats respectively) while upregulating endogenous

superoxide dismutase activity (26.52 U/ml in male rats and 24.8 U/ml in female rats

respectively). Polyphenols and flavonoids in ACV may have ameliorated existing lipid

peroxidation and enhanced endogenous antioxidant enzyme activity in response to restraint

procedure. However, ACV (4ml/kg) did not decrease (p<0.05) serum levels of stress

hormones corticosterone (315.43 ng/ml and 334 ng/ml) and epinephrine (38.14 pg/ml and 42

pg/ml) in male and female rats respectively. Females showed a higher stress response with

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CHAPTER 1

1.0 INTRODUCTION

1.1 Background to The Study

Stress has been defined in a multitude of ways by experts in various fields. It is a state of

disturbed homeostasis due to internal or external sources such as physical and psychological

stimuli known as stressors (Moazzam et al., 2013). Researches have shown that many clinical

disorders can either be induced or aggravated by stress (Adeoye et al., 2009).

Stress is followed by activation of the hypothalamopituitary adrenal and sympathoadrenal

axes. These axes serve as a neuroendocrine stress response systems and play vital role in the

maintenance of homeostasis (Dhabhar, 2009; Zafir and Banu, 2009; Saxena and Saxena,

2012). Hormones such as Corticotrophin releasing factor (CRF), adrenocorticotrophic

hormone (ACTH), glucocorticoids (GCs), and catecholamines (CA) are released from the

activated axes and are involved in the stress response (McEwen, 2008; Jameel et al., 2014).

The stress response also includes increased heart rate and blood pressure, increase blood

glucose level, protein catabolism, mobilization of free fatty acids and immunosuppression.

These reactions to stress are life-saving in the short term (acute stress) but become disruptive

and damaging in the long term (chronic stress) (Moazzam et al., 2013).

Immobilization and restraint are regarded as stressful conditions. They result in alterations or

disturbances in various body systems thus influencing many physiological aspects of an

organism. Physical restraint is a well-known stress model, which increases oxidative

processes. Severe and persistent stress elevates reactive oxygen species (ROS) production by

metabolic and physiological processes, causing cellular damage (Fazzino et al., 2010;

Tavakoli et al., 2012; Mosavat et al., 2014). Females are known to be more vulnerable to

stress and exhibit hyperactivity of the hypothalamopituitary adrenal axis function in

1

comparison to male animals and this has been identified to be at the level of the

hypothalamus (Chatterjee et al., 2006).

The word vinegar comes from the French word ―vin aigre‖ meaning sour wine (Waleed,

2012). It can be made from almost all carbohydrates that are fermentable such as dates,

sorghum, apples, pears, melons, potatoes and host of others. History has it that a Babylonian

courtier in 500 BC discovered wine which formed from unattended grape juice leading to the

eventual discovery of vinegar and its use as a food preservative (Mahmoodi et al., 2013).

Vinegar