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Luteinizing Hormone‐Releasing Hormone Neurons which are R‐etrogradely Labeled After Peripheral Fluoro‐Gold Administration in the Male Ferret
Author(s) -
Berglund Lee Ann,
Sisk Cheryl L.
Publication year - 1992
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.1992.tb00226.x
Subject(s) - median eminence , population , endocrinology , medicine , cell bodies , biology , circumventricular organs , axon , neurosecretion , hormone , hypothalamus , central nervous system , neuroscience , environmental health
This study identified luteinizing hormone‐releasing hormone (LHRH)‐producing neurons which have access to fenestrated capillaries in prepubertal male European ferrets. Fluoro‐Gold was injected intraperitoneally to retrogradely label neurons with terminals outside the blood‐brain barrier. LHRH neurons were identified by immunofluorescence using a secondary antibody tagged with tetramethylrhodamine isothiocyanate. Cell bodies which demonstrated both tetramethylrhodamine isothiocyanate and Fluoro‐Gold fluorescence were defined as LHRH‐producing neurons with axon terminals in regions containing fenestrated capillaries. The total number and neuroanatomical distribution of immunopositive (LHRH +) cells concurred with previous studies in the ferret in which cell bodies were diffusely distributed from rostral forebrain through caudal diencephalon, with approximately 70% of the LHRH + cell bodies located in retrochiasmatic hypothalamus. In the present study, an average of 59.8% of all LHRH+ neuronal perikarya also contained Fluoro‐Gold. The majority of Fluoro‐Gold filled LHRH+ neurons demonstrated only faint to moderate amounts of Fluoro‐Gold when compared to other Fluoro‐Gold filled neurosecretory neurons. This limited uptake of Fluoro‐Gold may be due to a relative inactivity of LHRH neurons projecting outside the blood‐brain barrier. Double‐labeled LHRH + neurons were dispersed throughout the entire population of LHRH+ cell bodies and no apparent nuclear groups of double‐labeled neurons were found. This observation suggests that the LHRH+ neurons responsible for neurosecretion into the median eminence coexist with the LHRH+ neurons responsible for intracerebral neurotransmission or neuromodulation. One distinguishable population of LHRH + neurons was consistently observed in all the brains. Only 26% of total LHRH+ perikarya within the caudal arcuate nucleus contained Fluoro‐Gold, while at least 50% of LHRH+ neurons in other structures, including the rostral arcuate nucleus, contained Fluoro‐Gold. Thus, in the prepubertal male ferret, the majority of LHRH cell bodies located in the caudal arcuate nucleus may be differentially regulated and/or involved in non‐neuroendocrine functions.