SEX VARIATION ON THE EFFECTS OF CARICA PAPAYA SEED EXTRACT ON RED BLOOD CELL, PACKED CELL VOLUME AND HAEMOGLOBIN IN MALE AND FEMALE WISTAR RATS

ABSTRACT
The effects of oral administration of different doses ofCaricapapayaseed extracts on haematological parameters specifically red blood cells (RBC), packed cell volume (PCV) and haemoglobin concentration in male and female wistar rats was examined. Previous studies have shown that Carica papaya has antisickling effects (Sofoworaet al., 1975), antifertility effects (Chinoyet al., 1997), membrane stabilization effects (Priyangaet al., 2012), nephroprotective effects (Olagunjuet al., 2009) and these effects tend to vary with sex. Other possible variations on the effects of Carica papaya seed extract due to sex is being investigated in this study.
Blood samples were taken by cardiac puncture from twenty (20) male and twenty (20) female wistar rats which were divided into four groups (n=5) each and graded dosages of Carica papaya seed extracts administered for twenty-one days (three weeks). The red blood cell mass, haemoglobin concentration and packed cell volume of the rats was determined by routine methods.
Two-way analysis of variance followed by Student’s T-test were performed on data and differences were considered statistically significant for p<0.05. There was an increase in parameters studied with response being higher in males than in females. Significant difference wereobserved between males and females only in red blood cell count though there were slight differences in the other parameters. 
This study showed that Carica papaya seed extract has haemato-stimulatory effects on both males and females with higher response in males which is via another mechanism apart from its effects on sex hormones.

CHAPTER ONE

INTRODUCTION

1.1   BACKGROUND STUDY

Blood is a special type of connective tissue composed of formed elements in a fluid matrix. The formed elements include red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (Bacha and Bacha, 2000). It is a bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.
Assessment of haematological parameters can be quite informative about the health status of the individual and it is among the methods which may not be apparent during physical examination but may affect the fitness of the animals (Kronfeld et al., 1969). The red blood cell count, white blood cell counts, packed cell volume and haemoglobin concentration are regularly measured haematological parameters but this study is concerned with red blood cells, packed cell volume and haemoglobin.
Most of the haematological parameters are influenced by factors like sex, age, breed, seasonal variations, lactation, health and nutrition status (Aengwanich, 2002; Al-shami, 2007; Mohammed et al., 2007). Since it is a well-documented fact that there are variations due to age, sex, attitude etc. (Hawkins et al., 1954, Viteri et al.,1972, De Grunch et al.,1989), it is acknowledged that for comparisons between individuals and with reference data in a clinical diagnostic situation, it is necessary to consider normal variations due to sex, age and breed in order to increase diagnostic precision (Satue et al., 2009). It has however been observed that the modifications correlated with sex, age and taxonomic position are best shown by the erythrocytic counts (Duguy 1970).
SEX VARIATION IN RED BLOOD CELLS, PACKED CELL VOLUME AND HAEMOGLOBIN CONCENTRATION
Red blood cells are the most common type of blood cells and the vertebrates’ organism’s principal means of delivering oxygen to the body tissues via blood flow through circulatory system (Pierige et al., 2008). They are also called erythrocytes. They are biconcave and anucleated and there are about 5.2 million red cells per cubic millimeter of blood in the adult human (4.7 to 6.1 million in males and 4.2 to 5.4 million for females). They take up oxygen and release it while squeezing through the body’s capillaries. They are formed in the bone marrow and the average life cycle of a red blood cell is 120 days. Erythropoietin and oxygen levels are factors that regulate the production of red blood cells.
Haemoglobin is an iron-containing biomolecule found in red blood cell cytoplasm for transporting oxygen and carbon (iv) oxide. Iron can bind to oxygen and heme is responsible for the blood’s red colour. It also carries some of the waste products back and from the tissue. It is concerned with blood’s ability to carry oxygen and iron. Low iron could lead to morbidity and mortality. On the average, haemoglobin concentration for males is about 14 – 18g/dl and 12 -16g/dl.
The haematocrit is also known as packed cell volume or erythrocyte volume fraction. It is the volume percentage (%) of red blood cells in blood.it was coined in the year 1903. It comes from the Greek words ‘hema’ meaning blood and ‘krites’ meaning gage or judge. It is normally higher in males than in females and that is about 45% in men and 40% for women (Purveset al., 2004). It can be determined by centrifuging heparinized blood in a capillary tube at 10,000 RPM for five (5) minutes. The volume of packed red blood cells divided by the total volume of blood sample gives packed cell volume. It can also be calculated from automated analyzer.
Mean red cell mass and hematocrit levels are higher in men than women but the reason for this is yet to be discovered. It was reported that testosterone and other androgens have an erythropoietic stimulating effect that can cause polycythemia, which manifests as an increase in hemoglobin, hematocrit, or red blood cell count (Siddique et al., 2004, Dobs et al., 1999).Some studies however do not agree with this theory. It was reported that the increase of hemoglobin depending on testosterone is not along with the increase of erythropoietin. Hence another mechanism was proposed which stated that androgens increased the response of immature bone marrow cells to the effects of erythropoietin which in turn stimulates the production and regulation of red blood cells. However, other studies have shown that greater increase of hematocrit and hemoglobin observed in older males during testosteronetherapy is due to changes in erythropoietin rates (Alexanian, 1969). There is an important difference between male and female genders in testosterone and hematocrit rates but there is no important difference in their erythropoietin rates (Molinari, 1982). Then, androgens stimulate haematogenesis by a passage other than erythropoietin. Also the studies on patients with renal disease demonstrated that erythropoietin does not react to androgentherapy (Dobs et al., 1999). In contrast, studies have shown that estrogen can inhibit the production of red blood cells (Watanuki et al.,2002). Hence it can be seen that the sex of an individual is a determining factor on the haematological factors.

CARICA PAPAYA

In the long history of the world, plants have been used medicinally. A large and increasing number of patients use medicinal herbs or seek the advice of their physician regarding their use (‘O’ Hara et al., 1998). It has been estimated roughly, that presently more than half of the total population of the world use herbal drugs (Chang, 1987). Increasing interest in medicinal herbs has increased scientific scrutiny of their therapeutic potentials and safety thereby providing physicians with data to help patients make wise decisions about their use (‘O’ Hara et al., 1998).