Abstract
Opioid peptides and cholecystokinin (CCK) have been shown to play a role in regulation of feeding behavior. Another neuropeptide that has recently been suggested to be involved in feeding is vasopressin. We explored possible interactions between opiates, CCK and vasopressin in feeding regulation by studying feeding suppression produced by naloxone and CCK in Brattleboro (DI) rats, which are homozygous for diabetes insipidus and lack the ability to synthesize vasopressin. Ten DI and 15 age-matched Long Evans (LE) rats were food deprived for 14 hours on two different days and then injected with naloxone (2.5 mg/kg) on one day or saline on the other. Thirty minutes later the food was returned and food and water consumption were measured after 1, 3 and 4 hr. Naloxone suppressed the food consumption of both DI and LE rats but the suppression was greater for the DI rats. This result was specific to feeding as water consumption was suppressed in LE more than in DI rats. Two weeks later, the same rats were food deprived for 6 hours on two different days and then injected with CCK-8 (2.5 μg/kg) on one day and with saline on the other. Food was returned one minute after the injection and food and water consumption were measured 30 and 60 minutes later. Food intake was reduced equally for both DI and LE rats. Water intake was not reduced. The results suggest that the suppression of feeding by CCK does not require an intact vasopressinergic system. The greater feeding suppression by naloxone in DI rats may suggest that opiates are interacting with vasopressin in producing their effects on food intake.
| Original language | English |
|---|---|
| Pages (from-to) | 763-767 |
| Number of pages | 5 |
| Journal | Peptides |
| Volume | 8 |
| Issue number | 5 |
| DOIs | |
| State | Published - 1987 |
| Externally published | Yes |
Bibliographical note
Funding Information:Neurons within the PVN were shown to contain several peptides including opiate peptides \[35\]a nd CCK \[5\].T hese peptides are sometimes colocalized with neurohypophysial hormones. For example, dynorphin and Leu-enkephalin were found in vasopressin-containing cells \[39\] ane Met-enkephalin and CCK were found in oxytocin containing cells \[29\].I nteractions between opiates and vasopressin were also found in physiological studies. For example, endogenous 1The research was supported by grants USPHS NIH NS11618 and Program Project HD 05958 awarded to J. Garcia, a gift from the David H. Murdock Foundation for Advanced Brain Studies and grant NSERC A1221 awarded to M. Holder. 2Requests for reprints should be addressed to Raz Yirmiya, Department of Psychology, University of California, Los Angeles, Los Angeles, CA 90O24-1563.
Keywords
- Brattleboro
- Cholecystokinin (CCK)
- Diabetes insipidus
- Drinking
- Feeding
- Naloxone
- Opiates
- Paraventricular nucleus
- Vasopressin
