The periaqueductal gray: A site eliciting gender differentiated responses in opioid analgesia.
Item
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Title
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The periaqueductal gray: A site eliciting gender differentiated responses in opioid analgesia.
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Identifier
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AAI3024809
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identifier
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3024809
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Creator
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Krzanowska, Eliza.
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Contributor
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Adviser: Richard J. Bodnar
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Neuroscience | Health Sciences, Pharmacology
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Abstract
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Sex differences in antinociception are commonly observed following systemic and intraventricular administration of opioids with male rats displaying more marked antinociceptive responses than female rats. The purpose of this dissertation research was to identify a potential brain site and mechanisms which elicit these sex differences. We hypothesized that the ventrolateral periaqueductal gray (vlPAG) is subject to sex differences in opioid antinociception due to its common critical roles in both antinociceptive and reproductive behaviors. We also examined whether these sex differences are mediated by either activational or organizational effects of gonadal hormones which are respectively altered by adult neonatal or neonatal gonadectomy. Thus, the first experiment evaluated sex differences and adult gonadectomy effects in morphine antinociception elicited from the vlPAG. To assess generalizability of these effects, the second experiment evaluated sex and adult gonadectomy differences upon antinociception elicited by the opioid agonists, beta-endorphin and D-Proendomorphin-2 in the vlPAG. Sex differences in motor activity elicited by these two agonists were also assessed. The third and final experiment evaluated sex and neonatal gonadectomy differences in vlPAG morphine antinociception.;Male rats displayed significantly greater magnitudes of antinociception elicited by morphine and beta-endomorphin in the vlPAG than female rats. In contrast, D-Pro2-endomorphin-2 antinociception in the vlPAG on the tail-flick test was significantly greater in female rats than in males, but these effects appeared secondary to sex-specific alterations in motor activation elicited by D-Pro2-endomorphin-2 in the vlPAG.;Adult gonadectomy failed to alter antinociception elicited by morphine in the vlPAG in males, but slightly enhanced morphine antinociception in female rats. In marked contrast, neonatal gonadectomy in males produced a pattern of vlPAG morphine antinociception that was indistinguishable from that of sham-treated females. Moreover, neonatal androgenization of females increased the magnitude of vlPAG morphine antinociception to a level similar to that of sham-operated males. Collectively, these results strongly implicate vlPAG and organizational effects of gonadal hormones in mediating sex differences in opioid antinociception in rats.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
