Distribution of somatostatin in the brain and of somatostatin and thyrotropin-releasing hormone in peripheral tissues of the chicken

Our research group recently presented the distribution of thyrotropin-relea sing hormone (TRH) in the chicken brain. In this study we measured somatost atin (SRIH) concentrations in different brain parts and nuclei. The distrib ution of SRIH and TRH in peripheral tissues was also studied. Although the highest SRIH content was found in endocrine areas like diencephalon and med ian eminence (ME), high levels were also recorded in brain stem and several hypothalamic nuclei which do not project to the ME. SRIH immunoreactivity was also found within the pituitary. In peripheral tissues, SRIH was mainly present in gonads, thyroid and intestine. Low amounts were found in duoden um, kidney, heart and lung. SRIH concentrations were barely detectable (liv er, blood cells) or undetectable (muscle, skin, spleen) in other peripheral tissues investigated. Although TRH was found in all tissues collected, it was also most abundant in brain, pituitary, thyroid and gonads. Our results suggest that also in the chicken SRIH and TRH are implicated in the contro l of several physiological processes like growth, reproduction and digestio n. (C) 2000 Elsevier Science B.V. All rights reserved.