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Reversible inhibition of sperm receptor synthesis for contraception

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Title: Reversible inhibition of sperm receptor synthesis for contraception.
Abstract: Methods are disclosed for reversibly inhibiting sperm receptor activity in animals. Nicarbazin, its derivatives and modifications which retain pharmacological activity are shown to inhibit activity of zona pellucida proteins and concomitant synthesis and/or assembly of the sperm receptor on the oocyte surface necessary for fertilization. Nicarbazin is easily administered, for example by simple addition to feed of an animal and is and non-toxic to the animals, providing a safe and efficient means for controlling populations of mammals and avian species. ...

Browse recent Mckee, Voorhees & Sease, P.L.C Attn: Pennsylvania State University patents - Des Moines, IA, US
USPTO Applicaton #: #20110034494 - Class: 514274 (USPTO) - 02/10/11 - Class 514 
Drug, Bio-affecting And Body Treating Compositions > Designated Organic Active Ingredient Containing (doai) >Heterocyclic Carbon Compounds Containing A Hetero Ring Having Chalcogen (i.e., O,s,se Or Te) Or Nitrogen As The Only Ring Hetero Atoms Doai >Hetero Ring Is Six-membered Consisting Of Two Nitrogens And Four Carbon Atoms (e.g., Pyridazines, Etc.) >1,4-diazine As One Of The Cyclos >Pyrimidines With Chalcogen Bonded Directly To A Ring Carbon Of Said Pyrimidine Moiety >Chalcogen Bonded Directly To Pyrimidine At 2-position

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The Patent Description & Claims data below is from USPTO Patent Application 20110034494, Reversible inhibition of sperm receptor synthesis for contraception.

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This application is a continuation application of U.S. Ser. No. 11/833,472 filed Aug. 3, 2007, which claims priority under 35 U.S.C. §119 of provisional application Ser. Nos. 60/821,445 filed Aug. 4, 2006 and 60/913,034 filed Apr. 20, 2007, which applications are hereby incorporated by reference in their entirety.


Nicarbazin has been used for over 50 years to control coccidiosis, an infection of protozoan parasites, in domestic poultry (see review by Chapman, 2001). While the exact mode of action of is unknown, several biochemical effects have been reported. One of the most acknowledged effects of nicarbazin on cells is to cause a leakage of potassium ions across the cell membrane along with an effect on mitochondrial energy production (Long, 1978). It is unclear how either of these effects influences the parasite itself, although nicarbazin has differential effects during the life cycle of the protozoan Eimeria—directly inhibiting both the asexual and sexual aspects of reproduction (Danforth, 1997; Xie, 1991).

In the poultry industry, nicarbazin is commonly administered to growing, meat-type chickens (e.g., broilers). However, when mistakenly added to the feed of egg-laying chickens, depigmentation of egg-shell color and egg production drop precipitously within a matter of days (Ott et al., 1956; Sherwood et al., 1956). These older studies clearly demonstrated a drug dosage effect among broiler-breeder hens; demonstrating that lower levels of nicarbazin (<125 ppm) produced a significant reduction in hatchability of fertile eggs. Higher levels (ca. 700 ppm) eliminated egg production entirely. However, all studies demonstrated that normal hatchability and egg production returned within 7-10 days following the removal of nicarbazin from the feed.

Chapman (2001) and others (e.g., Jones et al., 1990) suggest that nicarbazin functions to reduce hatchability of chicken eggs via the creation of ‘leaky membranes’ within the egg. Applicants have found that the main effect of nicarbazin was to alter the structure of the oocyte membrane by altering the structure and/or assembly of the primary protein composing the membrane (i.e., zona pellucida protein C (ZPC)). ZPC is also the primary sperm receptor among birds, mice, rats, cows and humans. Which thus would make the protocol useful in other animals besides just birds.

It is an object of the present invention to provide pharmaceutical compositions and methods for contraception in mammals.

It is yet another object of the invention to provide a method of contraception for animals and in particular, mammals, that is reversible.

It is yet another object of the invention to provide a method for animal contraception that may be orally administered, by for example, addition to feed of animals.

Other objects of the invention will become apparent from the description of the invention which follow.


The invention is in the field of reproductive physiology. Novel contraceptive agents are disclosed based on their ability to interfere with sperm receptor synthesis.



According to the invention, nicarbazin, its derivatives and modifications which retain activity, have been found to reversibly inhibit sperm receptor synthesis by the granulosa cells (in birds) and the oocyte (in mammals). Inhibition of synthesis and/or assembly of the sperm receptor on the oocyte surface, is necessary for fertilization take place. Thus the invention encompasses a novel pharmaceutical composition for contraception in both the avian and mammalian species comprising nicarbazin, its derivatives and modifications and a pharmaceutically acceptable carrier. The contraceptive activity occurs only upon administration of the nicarbazin and is reversed with the compound is no longer present. The nicarbazin can be administered in any manner such as, by addition to feed.

The pharmaceutical composition of the invention allows for an effective contraceptive strategy that does not involve any of the traditionally accepted hormonal mechanisms of oocyte development and/or maturation.

In yet another embodiment, the invention may be used to further study the sperm receptor interaction and identify agents which modulate the same for affecting fertility in animals, by screening for agents which affect ZPC transcription or translation and either reverse or enhance the effects of nicarbazin.


FIG. 1 is a Western blot of chicken ZPC proteins. Lanes 1=chZPC; 2=22 kd chAPC, 3=granulosa cell extract; 4=1 mM nicarbazin; 5=10 mM nicarbazin′ 6=100 mM nocarbazin (all cells were dead).

FIG. 2 shows the egg production of Pekin Ducks fed varying doses of nicarbazin. Gray represents 95% confidence intervals of the regression of the control group—any data points that fall outside this area are significantly different from the controls.]

FIG. 3 depicts the fertility of laid eggs obtained from Pekin Ducks fed varying doses of nicarbazin. The gray area represents 95% confidence intervals of the regression of the control group—any data points that fall outside this area are significantly different from the controls.

FIG. 4 shows the immunoreactive proteins (to a ZP3 antibody) from the perivitelline membrane of laid eggs from Pekin ducks fed varying doses of nicarbazin. Drug feeding began in Week 2; making Week 1 and internal control.

FIG. 5 demonstrates the large number of brightly stained sperm trapped in the oocyte membrane of the fertile, control egg, while the nicarbazin treated hen laid only infertile eggs with many fewer sperm (insufficient number to insure fertilization). Ducks were inseminated with 200 million sperm, overall fertility of control duck eggs was 87% (of 49 eggs set), while the 500 ppm nicarbazin ducks had a fertility of 20% (of 5 eggs set). [Images were taken at 20× magnification with DAPI fluorescent stain.]

FIG. 6 is an electron micrograph of a mature follicle from control (C) and nicarbazin treated (T) hens.

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US 20110034494 A1
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