[Phe 1 Ψ(CH 2 -NH)Gly 2 ]NC(1-13)NH 2 does not antagonize orphaninFQ/nociceptin-induced prolactin release

Lack of involvement of dopamine and serotonin during the orphanin FQ/Nociceptin (OFQ/N)-induced prolactin secretory response

“…These results confirm our previous work (Bryant et al, 1998(Bryant et al, , 2002 that OFQ/N is a potent stimulus for prolactin secretion in female rats. They also indicate that, at a time when prolactin levels were Values are means of 5-6 sections from each of the anterior, medial and posterior arcuate nucleus (AN).…”

“…In spite of the difficulty of finding a specific OFQ/N antagonist, it seems unlikely that OFQ/N stimulation of prolactin secretion is mediated by actions at the A, n or y opiate receptor sites. We have previously shown that naloxone pretreatment did not block this effect (Bryant et al, 2002), although more specific receptor antagonists were not tested.…”

“…However, neither dose antagonized OFQ/N's stimulatory effect. We have also reported that neither [Phe 1 C (CH 2 -NH)Gly 2 ]NC(1-13)NH 2 (Bryant et al, 2002) nor Acetyl-RYYRIK-NH 2 (Janik et al, 2003), which have been reported to act as OFQ/N antagonists Berger et al, 1999) blocked the prolactin secretory response to OFQ/N. The lack of a definite crystal structure representation of the OP 4 receptor has been a limiting factor in the synthesis of useful receptor antagonists and agonists (Meunier et al, 2000).…”

“…Indeed, OFQ/N is a potent stimulus for prolactin secretion in male and female rats in a dose-and time-related manner (Bryant et al, 1998). This stimulatory effect of OFQ/N is not mediated by the A, y or n opiate receptors because naloxone did not antagonize the response (Bryant et al, 2002). To date, the neuroendocrine role of OFQ/N remains poorly characterized.…”

Hypothalamic Control of Prolactin Secretion, and the Multiple Reproductive Functions of Prolactin

“…212,213 It is possible that increased local release of enkephalin might 2. 218,219 Like other opioid peptides, OFQ effects on prolactin seem to be mediated by an action on TIDA neuronal activity. Pharmacological targeting using subtype-specific receptor antagonists suggests that mu and kappa receptor subtypes, but not the delta receptor, are critical to endogenous opioid peptide regulation of prolactin secretion during these times.…”