Carp Pituitary Homogenate Research Articles

Observations on a possible pheromonal stimulation of milt production in carp ( Cyprinus carpio L.)

Experiments were carried out in 200-m 2 earthen ponds or 2-m 3 bare tanks to evaluate stimulation of spermiation in male carp exposed to female carp undergoing ovulation after injection of carp pituitary homogenate (cph). Stimulation of spermiation was observed when fish were kept in earthen ponds but not in tanks. In a control group, intact males which were exposed to cph-injected males also showed a stimulation of spermiation in earthen ponds but not in tanks.

Advances and future prospects of controlled maturation and spawning of grey mullet ( Mugil cephalus L.) in captivity

Grey mullet ( Mugil cephalus L.) is a widely cultured species. Practical artificial propagation techiques for this species, however, have yet to be developed. In this paper, we discuss induced spawning techniques and research on controlling its reproductive cycle. Among the induced spawning techniques currently available, carp pituitary homogenate plus human chorionic gonadotropin and carp pituitary homogenate plus luteinizing hormone-releasing hormone analogue are the most promising. The latter hormone therapy is recommended. Maturation of male mullet can be successfully induced throughout the year by using 17α-methyltestosterone administered orally, injected or implanted. A practical hormone therapy for control of female mullet maturation is still under investigation.

The cost and effectiveness of CPH, HCG and LHRH-a on the induced spawning of grey mullet, Mugil cephalus

Two hormone injections, a primer and a resolver, were used to induce spawning in grey mullet. Combinations of carp pituitary homogenate (CPH), human chorionic gonadotropin (HCG) and luteinizing hormone-releasing hormone analogue (LHRH-a), each used as a primer or resolver, were tested in 60 spawning attempts. Another six fish received saline injections and served as sham controls. The cost and the response, in terms of spawning and fertilization rates, of each combination were evaluated. The CPH/LHRH-a treatment is the most reliable and cost-effective method. HCG can replace CPH in this treatment, but the cost is higher and the response poorer. The HCG/LHRH-a treatment can, however, be used for research purposes.

Positive results of induced spawning and larval rearing experiments with Mugil liza Val., a grey mullet from Cuban waters

Induced spawning and larval rearing experiments were carried out with Mugil liza at Tunas de Zaza, Cuba. Of the 39 females treated with hormones, viable eggs and larvae were obtained from 9 females with natural or artificial fertilization. The best results were obtained with mullet pituitary homogenate (15 mg/kg), HCG with mullet pituitary homogenate (27–54 I.U./g with 18–48 mg/kg), HCG alone (53.1–60 I.U./g) and HCG with carp pituitary homogenate (12–41 I.U./g with 29.2–48 mg/kg) in that order, administered in three injections at 24-h intervals.

Induced spawning of grey mullet ( Mugil cephalus) by LHRH-a

The application of a high potency synthetic analogue of luteinizing hormone-releasing hormone (LHRH-a), des Gly 10 [D-Ala 6] LHRH ethylamide for inducing the final stages of maturation and spawning in the grey mullet was investigated. Two LHRH-a injection strategies were used. The first involved the use of carp pituitary homogenate (CPH) as a priming injection for females with average egg diameters of 600 μm or more. This injection was followed, 24 h later, by a resolving injection of LHRH-a. The second stragegy followed the same time frame but LHRH-a was used exclusively for both priming and resolving injections. A high spawning success rate (94.1%) was achieved utilizing the first strategy. Fertilization rates, hatching rates, and qualitative changes in egg morphology were similar to those reported using traditional methods. In this study, 20 mg/kg CPH followed by 200 μg/kg LHRH-a were the minimum dosages that resulted in fertilized spawns. This is the most cost-effective method developed to date for inducing grey mullet to spawn. A 68.4% success rate was achieved when utilizing the second strategy. The minimum total dosage that resulted in fertilized spawns was between 300 and 400 μg/kg LHRH-a. One-third of the total dosage was administered in the priming dose followed by the remaining two-thirds in the resolving injection.

Joint action of carp ( Cyprinus carpio L.) pituitary homogenate and human chorionic gonadotropin (HCG) in carp oocyte maturation and ovulation: In vitro and in vivo studies

In an in vitro study it has been shown that HCG at a dose of 100 i.u./ml does not cause an increase in the percentage of mature oocytes (follicles) compared to a control incubation. However, HCG together with carp pituitary homogenate (c.p.h.) at ratios of 6:4, 5:5, 4:6 (dosages of 60, 50, 40 i.u./ml of HCG and 40, 50, 60 μg/ml of c.p.h.) gave a higher mean percentage of mature follicles than did c.p.h. alone at a dose of 100 μg/ml. Based on the in vitro results, in vivo experiments with HCG and c.p.h. were conducted in order to decrease the amount of c.p.h. used in the induction of artificial spawning in carp. Experiments were carried out on 200 adult female carp. The use of HCG and c.p.h. in two injections (ratios 6:4, 5:5 and 4:6) at a dose 10 times higher than in the in vitro experiment did not increase either the percentage of mature oocytes or the number of ovulated females compared to groups injected with c.p.h. alone at the same dose. Classical hypophysation induced ovulation in the majority of injected females (60–80%). The results indicate that HCG with c.p.h. is ineffective in reducing the amount of c.p.h. required for artificial spawning of carp.

Effects of salinity on egg development and hatching in grey mullet Mugil cephalus L.

Grey mullet, Mugil cephalus, collected from ponds were induced to spawn with carp pituitary homogenate and human chorionic gonadotropin (HCG) at 30%o salinity and 26° C. The spontaneously spawned and fertilized eggs were transferred to sea water of different salinities in the range of 5–70%o, either at the 2‐blastomere or the gastrula stage. Those eggs transferred at the gastrula stage were more tolerant to the salinity change than were those transferred at the 2‐blastomere stage. The eggs did develop to the embryonic stage within the salinity range from 5 to 60%o. Hatching occurred in all salinities between 10 and 55%o. However, no larvae survived at 10 or at 55%o. The optimal salinity range for eggs incubating at 22.0–25.5° C was from 30 to 40%o salinity, with the peak at 35%o.

Prolactin and pituitary control of calcium regulation in the killifish, Fundulus heteroclitus.

Abstract Hypophysectomized killifish ( Fundulus heteroclitus ) adapted to calcium-deficient seawater showed significant decreases in plasma calcium levels 8 days after the operation. At Day 16, plasma calcium levels were no longer significantly different from those of operated control fish. Plasma sodium and potassium levels were unaffected at all time periods. Injections of whole carp ( Cyprinus carpio ) pituitary homogenate corrected the hypocalcemia seen in the hypophysectomized killifish. When the carp glands were divided into “anterior”, “middle”, and “posterior” portions and tested in the hypocalcemic fish, the “middle” portion had the greatest corrective effect. Histological studies demonstrated that this portion probably contains the largest number of prolactin cells. In all cases, plasma sodium levels were elevated. In one experiment, a prolactin cell-free “posterior” portion had no hypercalcemic or hypernatremic effect. Injections of prolactin produced a log-dose-related hypercalcemia and hypernatremia in the hypophysectomized killifish. The highest dose of prolactin used (10 μg/g of body wt per injection) had a reduced hypercalcemic effect. Based on all these data, we suggest that prolactin may be the pituitary hypercalcemic principle in the killifish.