Tamoxifen Decreases Level of Immunoglobulins in Blood of the Hen (Gallus domesticus) without Alteration in Non‐Immunoglobular Fractions of Plasma Proteins

Abstract

The effect of tamoxifen (TMX), an anti-estrogen compound, on immunoglobulins (Ig) level in blood plasma of laying hens was investigated. TMX (4 mg/hen/day) was given per os for seven consecutive days; control hens received placebo. Blood samples were collected from the wing vein every day before TMX treatment, and plasma Ig levels were measured by means of Rlebodzinski's test. TMX significantly decreased plasma Ig levels, maximally by 51% on day 2 of the experiment. The observed reduction in Ig level was accompanied by the significant, 37% decrease in the ratio of Ig/total protein (Tp). From the third day of TMX treatment, level of Ig and the ratio of Ig/Tp gradually increased and on the day 5 of the experiment no difference between control and experimental group was found. In non-immunoglobular (Tp-Ig) fractions of plasma proteins no significant alterations after TMX treatment were observed. Therefore, treatment of laying hens with TMX transiently decreased plasma Ig levels. Most likely the effect of TMX is associated with the antagonistic properties of TMX toward estrogen receptors. On the contrary, the transient decrease in plasma Ig levels of TMX-treated hens followed by the gradual increase suggests adaptation of the immunological system to treatment with the anti-estrogen preparation.

Impact of Oral Supplementation of Different Levels of Tamoxifen on Productive and Reproductive Efficiencies and Carcass Traits of Avian48 and Arbor Acres Broilers

“…In this study, treatment of broiler chicken with Tamoxifen in different doses caused a gradual decrease in follicle production rate and eventually led to an increase in the atretic follicles at different stages of atresia. This result is consistent with previous findings that have shown that treatment of laying hens with Tamoxifen leads to a reduction in the rate of egg laying and evokes a pause in egg laying [ 28 ]. The gradual decrease in the rate of egg laying after Tamoxifen administration is probably associated with the abolition of the central action of oestrogens at the hypothalamo-pituitary axis.…”

Effect of tamoxifen on sex steroid concentrations in chicken ovarian follicles

“…In the present study, treatment of laying hens with TAM caused a gradual decrease in egg-laying rate and eventually brought it to an end after twelve days of treatment. This result is consistent with previous findings which demonstrated that treatment of laying hens with TAM leads to a decrease in egg-laying rate and evokes a pause in egg laying (Wilson and Cunningham, 1981;Sechman et al, 2004a). The results obtained support the assumption that in the laying hen oestrogens are actively involved in the mechanism regulating the preovulatory release of LH.…”

“…Therefore, it was applied in several previous studies in poultry to examine the role of oestrogens in physiological processes at various ages (Wilson and Cunningham, 1981;Asem and Hertelendy, 1986;Jaccoby et al, 1992;Lisowski and Bednarczyk, 2005). In our previous study we showed that the administration of TAM to laying hens resulted in a decrease in the total immunoglobulin concentrations of the blood plasma without alteration of the non-immunoglobular fractions of plasma proteins (Sechman et al, 2004a). In the present study, treatment of laying hens with TAM caused a gradual decrease in egg-laying rate and eventually brought it to an end after twelve days of treatment.…”

“…The effects of these steroids in the target cells are mediated by oestrogen receptors (ERs) which are expressed not only in the ovary and oviduct but also in several other tissues, including the hypothalamus and pituitary gland (Gasc and Baulieu, 1988;Hrabia et al, 2004). Our recent study has revealed that tamoxifen (TAM), a nonsteroidal ER antagonist, decreases total immunoglobulin concentrations in the blood plasma of the laying hen (Sechman et al, 2004a). In the present work we applied TAM to study the effect of blockage of oestrogen receptors on the process of steroidogenesis in the chicken ovary.…”

Experimental (Antiestrogen‐Mediated) Reduction in Egg Size Negatively Affects Offspring Growth and Survival

“…We found no difference in posttreatment body mass between tamoxifen-and sham-treated females in this study, and we have evidence that tamoxifen treatment does not adversely affect hematological parameters or endogenous estradiol levels (E. Wagner, unpublished data). In addition, previous studies have found that tamoxifen treatment does not alter body mass, bone density, fat stores, plasma protein and calcium levels, food consumption, or activity level in reproductively mature female birds (Jaccoby et al 1995;Wilson and Thorp 1998;Lupu 2000;Sechman et al 2004). It is also unlikely that tamoxifen had any direct effects on parental behavior and chick provisioning, particularly because treatment did not extend beyond initial stages of egg production and the effects of tamoxifen are transient and reversible (Williams 2000(Williams , 2001.…”