Effects of an ACTH 4-9 related peptide upon intracranial self stimulation and general activity in the rat

Adult male Sprague-Dawley rats were stereotactically implanted with electrodes within the anterior medial forebrain bundle: The rats were trained to respond for intracranial self-stimulation (ICS) and treated with control solution or varying doses of an ACTH 4-9 related synthetic peptide (Org 2766; H-Met(O 2 )-Glu-His-Phe- d -Lys-Phe-OH). The drug affected ICS as measured in overnight response records, with the highest dose reliably increasing the amount of responding. In a second experiment rats were similarly treated and general activity was assessed. No remarkable changes in activity were present at any tested dose. The findings corroborate previous reports suggesting ACTH-related peptides may be active in a variety of motivated tasks, but less active with respect to general activity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46417/1/213_2004_Article_BF00433254.pd

Classification of neuromuscular blocking agents in a new neuromuscular preparation of the chick in vitro

A neuromuscular preparation of the chick is described: 1. 1. The sciatic nerve-tibilis anterior muscle preparation of the 2–10 days old chick fulfils all criteria of an assay preparation and differentiates between curare-like and decamethonium-like agents. 2. 2. The preparation responds to supramaximal nerve stimuli with twitches, which are of constant height during 6–8 hr. The twitch amplitude is decreased by curare-like drugs in concentrations of 0.5 μg/ml and more. This effect is dose-dependent. 3. 3. The preparation responds to the administration of decamethonium-like drugs with a slow contracture, the force and velocity of which is dose-dependent, and a decrease in the height of the twitch. The time curve of these two effects of decamethonium-like drugs is not the same. Threshold dose for contractures is about 0.1 μg/ml. 4. 4. Curare-like compounds in doses of times threshold and more antagonize or prevent the slow contractures caused by decamethonium-like drugs, dose-dependently. 5. 5. The effects are easily reversible and also reproducible in the same preparation during a day. 6. 6. A resemblance is suggested between the chick slow fibre response and the responses of the cat extra-ocular muscle and the mammalian intrafusal muscle to decamethonium-like compounds; the possibility of a presynaptic site of action apart from a post-synaptic one of the decamethonium-like drugs in the chick muscle is postulated

The effects of ACTH- and vasopressin-analogues on CO2-induced retrograde amnesia in rats

Amnesia for a one-trial step-through passive avoidance response was induced in rats by application of CO2 until respiratory arrest occurred. The ACTH-analogue ACTH4–10 alleviated the amnesia when administered 1 hr prior to the retrieval test but not when given 1 hr prior to the acquisition trial. The behaviourally inert ACTH-analogue ACTH11–24 appeared to have no effect on the amnesia. The vasopressin-analogue desglycinamide lysine vasopressin (DG-LVP) antagonized the amnesia when administered 1 hr prior to the acquisition trial or 1 hr prior to the test trial. The relevance of these date to present theories on amnesia is discussed