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Opioid stimulation in the ventral tegmental area facilitates the onset of maternal behavior in rats

Thompson, Alexis C. and Kristal, Mark B. (1996) Opioid stimulation in the ventral tegmental area facilitates the onset of maternal behavior in rats. [Journal (Paginated)]

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Abstract

This research investigated the effect of an increase or decrease in opioid activity in the ventral tegmental area (VTA) on the onset of maternal behavior in rats. In Experiment 1, the latency to show maternal behavior toward foster rat pups (sensitization latency) was determined in maternally naive female rats given either nothing or a unilateral intra-VTA injection of morphine sulfate (MS) (0.0, 0.01, 0.03, 0.1 or 0.3 µg), on the first three days of a 10-day period of constant exposure to pups. Rats treated with 0.03 µg MS had significantly shorter sensitization latencies than did rats treated with 0.0 µg MS, 0.01 µg MS, or receiving no treatment (higher doses of morphine produced intermediate results). The facilitating effect of intra-VTA MS on the onset of maternal behavior was blocked by pretreatment with naltrexone hydrochloride and was found to have a specific site of action in the VTA (MS injections dorsal to the VTA were ineffective). In Experiment 2, sensitization latencies were determined in periparturitional rats given a bilateral intra-VTA injection of either the opioid antagonist naltrexone methobromide (quaternary naltrexone), its vehicle, a sham injection, or left untreated 40 min after delivery of the last pup. The mothers' own pups were removed at delivery; mothers were nonmaternal at the time of testing. Quaternary naltrexone treatment produced significantly slower sensitization to foster pups than did control conditions. Total activity and pup-directed activity did not differ significantly with treatment. The results demonstrate that increased opioid activity in the VTA facilitates the onset of maternal behavior in inexperienced nonpregnant female rats, and decreased opioid activity in the VTA disrupts the rapid onset of maternal behavior at parturition.

Item Type:Journal (Paginated)
Keywords:Maternal behavior, Opioids, Mesolimbic, Ventral tegmental area, Naltrexone methobromide, Morphine, Parturition, Rat
Subjects:Neuroscience > Behavioral Neuroscience
Biology > Behavioral Biology
Psychology > Comparative Psychology
Neuroscience > Neuroanatomy
Neuroscience > Neurochemistry
Neuroscience > Neuroendocrinology
Neuroscience > Neuropharmacology
Neuroscience > Neurophysiology
Psychology > Physiological Psychology
Psychology > Psychobiology
ID Code:6311
Deposited By:Kristal, Mark B.
Deposited On:05 Jan 2009 23:58
Last Modified:11 Mar 2011 08:57

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