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Inhibition of Tuberoinfundibular Dopaminergic Neural Activity During Suckling: Involvement of μ and κ Opiate Receptor Subtypes
Author(s) -
Callahan Phyllis,
Baumann Michael H.,
Rabii Jamshid
Publication year - 1996
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 - 10.1046/j.1365-2826.1996.05207.x
Subject(s) - medicine , endocrinology , dopaminergic , prolactin , median eminence , hypothalamus , opiate , serotonergic , antagonist , receptor antagonist , opioid , dopamine , κ opioid receptor , chemistry , receptor , serotonin , hormone
Previous studies have shown that mu (μ) and kappa ( κ ) opioid antagonists inhibit suckling‐induced prolactin release. Prolactin responses elicited by pup suckling or opioid administration are mediated, at least in part, by suppression of dopamine (DA) release from tuberoinfundibular dopaminergic (TIDA) neurons in the hypothalamus. We examined the effects of the μ opiate receptor antagonist, β ‐funaltrexamine ( β ‐FNA), and the κ opiate receptor antagonist, nor‐binaltorphimine (nor‐BNI) on the activity of TIDA neurons in lactating rats. TIDA neuronal activity was determined by measuring DOPA accumulation in the caudate putamen (CP) and median eminence (ME). The effects of opioid antagonist treatment were determined in pup‐deprived (low circulating prolactin levels) or pup‐suckled rats (high circulating prolactin levels). The accumulation of 5‐hydroxytryptophan (5‐HTP) in the medial preoptic area (MPOA), the anterior hypothalamus (AH) and the median eminence (ME) was quantified as an index of serotonergic activity in the same animals for comparative purposes.