Prolactin is a polypeptide hormoe synthesised and secreted by the Adenohypophysis (anterior Pituritary gland) and the placenta. It is also produced in other tissues including the breast and the decidua. Pituritary prolactin secretion is regulated by neuroendrocrine neurons in the hypothalamus, most importantly by neurosecretory dopamine neurons of the arcuate nucleus, which inhibit prolactin secretion.

Prolactin is present in several body fluids, including blood plasma, amniotic fluid, milk, mucosal secretions and cerebrospinal fluid. Prolactin has many effects, the most important of which is to stimulate the mammary glands to produce milk (lactation). Other possible functions of prolactin include the surfactant synthesis of the fetal lungs at the end of the pregnancy and immune tolerance of the foetus by the maternal organism during pregnancy.

Prolactin may also have inhibitory effects on gonadal function when present in high concentrations. There is a diurnal cycle in prolactin secretion. During pregnancy, high circulating concentrations of estrogen promote prolactin production. The resulting high levels of prolactin secretion cause maturation of the mammary glands, preparing them for lactation. After childbirth, prolactin levels fall as the internal stimulus for them is removed.

High prolactin levels also tend to suppress the ovulatory cycle by inhibiting the secretion of both FSH and GnRH. Prolactin levels may be checked as part of a sex hormone workup, as elevated prolactin secretion can suppress the secretion of FSH and GnRH, leading to hypogonadism, and sometimes causing erectile dysfunction in men.

Elevations in plasma prolactin concentrations occur during ovulation, pregnancy, nursing and stress. Abnormal elevations in plasma prolactin levels (hyperprolactinemia) can occure as a result of pituitary adenomas, other anatomic and traumatic abnormalities, in response to certain pharmacologic agents and in hypothyroidism. Hypoprolactinemia (low prolactin levels) are observed in cases of hypopituitarism.

Prolactin ELISA:

Immunoenzymatic colorimetric method (ELISA) for quantitative determination of Prolactin in serum or plasma.

Principle of the Assay:

The essential reagents required for an immunoenzymatic assay include high affinity and specificity antibodies (enzyme-labelled and immobilised) with different and distinct epitope recognition, in excess and native antigen. Upon mixing monoclonal biotinylated antibody, the enzyme labelled antibody and a serum containing the native antigen, reaction results between the native antigen and the antibodies without competition or steric hindrance to form a soluble sandwich complex. The interaction is illustrated by the following equation:

BtnAb(m) = Biotinylated monoclonal antibody (excess quantity)
AgPrl = native Prolactin antigen (variable quantity)
EnzAb(p) = Enzyme labelled polyclonal antibody (excess quantity)
Ab(p)-AgPrl-BtnAb(m) = Antigen-antibody-sandwich complex
Ka = Rate constant of association
K-a = Rate constant of dissociation

Simultaneously the complex is deposited to the well through the high affinity reaction of streptavidin and biotinylated antibody. This interaction is illustrated below:

Streptavidin C.W. = Streptavidin immobolized on well.
Immobilized complex = Antibody-Antigen sandwich bound.

After equilibrium is attained, the antibody-bound fraction is separated from unbound antigen by decantation or aspiration. The enzyme activity in the antibody-bound fraction is directly proportional to the native antigen concentration. By using several different serum references of known antigen values, a dose response curve can be generated from which the antigen concentration of an unknown can be ascertained.

Specific performance characteristics:

Intra Assay Variation:

Within-run precision was determined by replicate determinations (20x) of three different control sera in one assay.

Inter Assay Variation:

Between-run precision was determined by replicate measurements of three different control sera in two different lots.

Analytical Sensitivity:

The lowest detectable concentration of Prolactin that can be distinguished from Standard 0 is 1.0 ng/ml.

Accuracy:

The NovaTec Prolactin ELISA was compared to another commercially available Prolactin assay. Serum samples of 65 subjects were analysed according in both test systems.
The linear regression curve was calculated:
r = 0.956

Order information: