Juxtapositions between the somatostatinergic and growth hormone-releasing hormone (GHRH) neurons in the human hypothalamus

Highlights • The majority of the GHRH perikarya received contacting somatostatinergic axonal varicosities in the human hypothalamus. • These juxtapositions may represent the morphological substrate of the somatostatin-influenced GHRH secretion in humans. • In contrast, GHRH fibers commonly avoided the close vicinity of the somatostatinergic perikarya. • This phenomenon indicates that GHRH does not have significant direct influence on the hypothalamic somatostatin secretion. • GHRH may regulate somatostatin release by either hormonal route or indirectly, via other neurotransmitter systems.