The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness

Abstract

Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin ( PRL ) levels, which is necessary for incubation and connected with changes in hypothalamic–pituitary–gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine ( PCPA ) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone ( P4 ), testosterone ( T ), estradiol ( E2 ), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [ GnRH ] I, luteinizing hormone [ LH ] ß, follicle-stimulating hormone [ FSH ] ß) and lactotrophic (vasoactive intestinal peptide [ VIP ], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LHß, and FSHß and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.

Determination of Annual Plasma Hormone Levels Associated with Reproduction in Long-Day Breeding Domestic Geese

“…The ELISA method applied in this study has been used for the determination of the levels of plasma gonadal steroid hormones and PRL for several years in the laboratory of the Department of Animal Science of The Hebrew University of Jerusalem in Israel. Until now, it has been used for the evaluation of gonadal steroids in plasma of domestic turkeys [ 31 ] and these hormones and PRL in laying [ 32 ] and broiler breeder chickens [ 33 , 34 ] and domestic geese [ 26 , 27 ].…”

“…This may be explained by the fact that by the end of the breeding–laying period some geese created natural nests. In chickens [ 32 ] and geese [ 35 ], incubation behaviour is related to plasma PRL elevation. Contrary to presented results, in long-day breeding geese Yang et al [ 14 ] observed that PRL level was the highest during the peak of egg production.…”

“…In flocks of domestic geese production of hatching eggs with optimal fertility during breeding–laying period determines profitability. Previous studies indicate that modulation of PRL with dopamine agonist [ 49 ] and blockage of serotonin synthesis [ 32 ] may enhance the reproductive efficiency of domestic hens. Also, using different photoperiod stimulation in the breeding–laying period like in the study by Zhu et al [ 15 ] may be considered in future work on Zatorska geese.…”

OPN5 Regulating Mechanism of Follicle Development Through the TSH-DIO2/DIO3 Pathway in Mountain Ducks Under Different Photoperiods

“…Gonadotropins regulate the secretion of gonadotropic hormones through blood circulation, which in turn promotes gonadal development and regulates animal reproduction ( Zhu et al, 2019a ; Zhu et al, 2019b ). In addition, in seasonally breeding avian species, nesting behavior associated with reproduction is an important biological feature and is related to neurotransmitters produced by the hypothalamus, pituitary gland and hypothalamus-pituitary-Gonadal axis (HPG)reproductive hormones ( Saelim et al, 2004 ; Gumułka et al, 2020 ). The HPG axis secretes a variety of hormones, including GnRH hormone at the hypothalamic level, prolactin (PRL),follicle-stimulating hormone (FSH), and luteinizing hormone (LH) hormones at the pituitary level, and E2 and P4 at the gonadal level and the nesting behavior is mediated by the action of ovarian E2 on the hypothalamus during egg laying, and that the enhanced activity of hypothalamic dopamine and pentraxin promotes the synthesis and release of Vasoactive Intestinal peptide (VIP) ( Gumułka et al, 2020 ), which in turn promotes the secretion of PRL through feedback ( Avital-Cohen et al, 2012 ).…”

Ovarian transcriptome profile from pre-laying period to broody period of Xupu goose

“…Heredity is also a fundamental factor that modulates broodiness. Emerging reports demonstrate that broodiness is a polygenic trait regulated by at least 2 dominant autosomal genes, implicated in multiple signal transduction pathways, including GnRH and Wnt pathways ( Yu et al, 2016a ; Gumułka et al, 2020 ). Heritability of nesting sex for waterfowl is only 0.116.…”