Objective- The pineal gland and its principal hormone melatonin play an important role in the circadian organization in birds. However, little is known about the role of melatonin in cardiac activity of broiler chicken. The aim of this study was to assess the impact of intracerebroventricular injection of melatonin in electrocardiographic parameters, heart rate and mean electrical axis in broiler chickens.
Design- Experimental study.
Animals- Forty male Ross broiler chickens
Procedures- Ross broiler chickens received intracerebroventricularly (ICV) melatonin. All ECGs were standardized at 1 mV = 20 mm, with paper speed of 50 mm/sec. Leads І, ІІ, ІІІ, aVR, aVL and aVF were recorded.
Results- Injection of melatonin (200 nmol) increased the duration of T wave and QRS complex and declined the heart rate as compared to the control group (p<0.05). Mean electrical axis, calculated from leads ІІ and ІІІ, did not differ between groups and it was between -93° and -99° in all chickens.
Conclusion and clinical relevance- Exogenous melatonin intracerebroventricularly results in sinusoidal bradycardia in broiler chicken