Summary: Pregnant rats were injected with a substance that caused autism-like symptoms in their babies. The male babies were put through tests with control animals to measure social interaction and anxiety. In feeding studies, they were deprived of food and water overnight. Some were fasted for 16 hours and killed by flushing their hearts.

Procedure: Female rats were mated, and some were injected with valproic acid (VPA) during pregnancy. This substance causes autism-like symptoms in the unborn litter. The mothers were allowed to care for their young for 25 days before they were taken away for experiments (only male rats were used; their sisters' fate was not stated). Behavioural tests were performed to test the symptoms:
a) Open Field Social Interaction, where one control and one VPA rat were recorded in a bright open field.
b) Elevated Plus Maze, where each rat was placed in a plus-shaped device with open and closed arms to observe their movements.
In the following feeding study, control and VPA rats were kept alone to measure their food and water intake. After a baseline period, the food was taken away overnight. Next, both food and water were taken away overnight. The weight gain was measured regularly for 225 days; their fate afterwards was not stated. Another group of control and VPA rats were fasted for 16 hours before being anaesthetised. Their hearts were flushed with saline and paraformaldehyde.

Purpose: To investigate the intake of 'bland' rat food in a rat autism model. One of the symptoms of Autism Spectrum Disorder (ASD) is high selectivity regarding food. Individuals often refuse to eat despite hunger unless preferred food is available. Brain processes highly regulate food intake. Hence, the study aimed to test the effect of food and water deprivation on later food intake.

Source: Journal article

Year published: 2022

Summary: Rats were force-fed with a probiotic solution or control solution. After two weeks, they were killed for dissection.

Procedure: Ninety rats were force-fed with a probiotic supplement or control solution; five more animals were left alone. One of the gavaged animals was injured in the process and euthanised. The others were observed for two weeks and then killed for dissection. The lesions found in their urinary tracts made it necessary to repeat the experiment with 300 more rats, getting a different food from the first group and the same supplement.

Purpose: To test the safety of a novel probiotic supplement for humans. Rats are often used to screen new foods or medications to test whether they are safe for human consumption. 

Source: Journal article

Year published: 2022

Summary: Female rats were kept alone and fed different diets containing normal or high amounts of fat or sugar. Some were supplemented with Greenshell mussel powder. X-rays were done several times, and some rats' ovaries were surgically removed. Ultimately, all were killed by bleeding them out to be dissected.

Procedure: Female rats were kept alone and fed the test diet for 14 weeks (short-term) or 36 weeks (long-term). The diet contained 15% protein, with the protein source being just casein (control) or 1/3 of it as Greenshell mussel powder (GMP). The test diet differed between groups in fat and sugar content (5% of each in normal and 30% in the high-fat or high-sugar diets). X-ray scans were performed at baseline and after 8 and 14 weeks on the experimental diets. An additional scan after 36 weeks was done on the long-term groups, and half of them underwent ovariectomy (the other half a sham surgery). In the end, all groups were deeply anaesthetised, and a blood sample was drawn directly from the heart. All were killed by bleeding them out, and fat pads were dissected.

Purpose: To study the relationships between obesity and bone mineral density (BMD) and to evaluate the potential health benefits of Greenshell mussel (GSM) on bone health. GSM is reported to have anti-inflammatory and anti-arthritis effects. It still seems unclear whether obesity has beneficial or detrimental effects on bone health in postmenopausal women. Despite evidence of increased BMD in obese adults, the risk of bone fractures is increased.

Source: Journal article

Year published: 2022

Summary: Rats and mice were anaesthetised, and their necks were broken. Their tissue was then used for research.

Procedure: Rats and mice were killed as part of routine colony maintenance. The animals were anaesthetised, and their necks were broken. Tissue was then collected to be used in laboratory assays for migraine research.

Purpose: To study the protein expression of a receptor and its relationship to another protein (CGRP) in a facial nerve of rats, mice and humans. These are known to play some role in migraines.

Source: Journal article

Year published: 2022

Summary: Some rats had their brains surgically heat-damaged. In another surgery, electrodes were implanted to monitor brain activity and to stimulate the damaged parts with light. Rats then had to re-perform memory tests to see the damage and light impact before all were killed.

Procedure: Rats were anaesthetised and put in a stereotaxic frame. An electrode was placed into a specific part of their brain to damage it with heat. Forty minutes later, they received infusions into the brain as pre-treatment for light stimulation later. Six weeks later, different electrodes were implanted in another surgery, fixed with six screws, and covered with dental acrylic.
For behavioural testing, food was restricted, maintaining 85% of their weight. A 12-arm maze (65cm long arms with walls, connected in the centre) was used to test memory. Rats had been trained before surgery to choose the correct arm of the maze (containing a chocolate treat). During the 16 days of testing, they had 8 days of light stimulation and 8 days of no stimulation.
The implanted electrodes were connected via cable to a recording device during the tests for brain activity measurement. After 90min in a dark room, rats were killed by anaesthetic overdose and flushing their heart with chilled saline, followed by paraformaldehyde. Their brains were then dissected. w

Purpose: To test if a specific brain region is responsible for memory. The study aimed to prove the “only limited and indirect support” for this hypothesis.

Source: Journal article

Year published: 2021

Summary: Rats were anaesthetised, and their inner ear was partly removed, then parts of their brains were stimulated over and over with wire electrodes. Reactions of the rat's eyes were recorded, and the brain's electrical response was measured with electrodes cemented into the brain. In the end, all were killed.

Procedure: Rats were anaesthetised and fixed in a stereotaxic frame with a bolt glued to the rat's forehead to keep it at a certain angle. The left side of the skull and some parts of the inner ear were destroyed and removed. They removed nerves and some bones to get to the parts they wanted to stimulate. Through wire electrodes and electrical stimulation software, sets of currents were sent into the respective areas. The rats "recovered" in-between sets "for at least 1min". Eye movements were used as a visible reaction to the stimulation. Responses of the brain were recorded through a bundle of 16 electrodes, fixed into the brain with dental cement. Ultimately, all rats were overdosed with anaesthetic, and their brains were removed.

Purpose: To research the communication between the balance/movement system and the brain. The vestibular system creates a sense of balance and spatial orientation for movement coordination. It is known as the labyrinth or inner ear.

Source: Journal article

Year published: 2021

Summary: Tinnitus was caused to rats by blasting one of their ears with 115Db for an hour; other rats served as control. Rats were taught that silence meant they would get electric shocks and freeze in fear. This was used to test for tinnitus. We exposed a similar paper as part of our 2021 12 Days of Christmas campaign.

Procedure: Male rats were anaesthetised and placed in a soundproof chamber. A pure tone at the level of a working chainsaw (115dB) was delivered directly to one ear through a speaker for 1 hour. The other ear was blocked with foam. Control animals were kept anaesthetised for the same time but without noise. Before and immediately after the trauma or sham trauma, the hearing function was measured with electrodes placed in the head.
Rats were then conditioned in a lick suppression test four weeks after the trauma/sham. They were deprived of water for most of the day and could only drink from a sipper tube in a test chamber with stainless steel rods for 15min per session. During the session, a constant white noise was played, except for 10 random 15-second intervals of either silence or a pure tone. The rat received a 3-second electric shock at the end of each silence. Drinking activity was measured, and conditioned rats reacted to the silence and stopped drinking. Rats with tinnitus would also stop during tones they could not hear. In the end, the animals were decapitated, blood collected, and their brains were removed.

Purpose: To test if noise trauma causes tinnitus and changes the brain’s metabolism. Following similar experiments, the study aimed to find a direct link between acoustic trauma, hyperacusis (sound sensitivity) and tinnitus.

Source: Journal article

Year published: 2021

Summary: Diabetic rats had significantly higher body weight, body fat, and blood glucose levels than their littermates. Rats were anaesthetised and had ultrasound images made from their hearts. All were given an anaesthetic overdose, and their heart was removed once no foot withdrawal reflex was seen.

Procedure: (We only have the preprint available for now.)
Male rats with a genetic mutation to build up fat and develop Type 2 diabetes were used together with their lean non-diabetic littermates. For heart ultrasound, rats were anaesthetised in a gas chamber and then transferred onto a heating pad. The chest was shaven to record heart functions. All rats were killed with an anaesthetic overdose. Once the paw withdrawal reflex was gone, their hearts were removed and used for analyses.

Purpose: To measure the calcium sensitivity in rats’ hearts, comparing healthy lean and diabetic fatty rats. It is known that diabetes causes heart problems, and the study aimed to test if decreased calcium sensitivity could be the reason.

Source: Journal article

Year published: 2021

Summary: Some rats were killed for dissection. Others were anaesthetised and put in a stereotaxic frame. Their skulls were drilled open to inject colchicine (a gout medication used here to improve brain imaging). They were anaesthetised again and killed 18 and 22 hours after surgery.

Procedure: Rats of different statuses (never pregnant, pregnant, new mums) were anaesthetised. Mother rats were separated from their babies at least 4 hours before surgery. Their brains were accessed through the mouth, and neuron reactions to stimuli were measured with electrodes. In the end, they were killed with an anaesthetic overdose. Other rats were anaesthetised and killed by flushing their hearts with saline and paraformaldehyde. The fate of the babies was not stated.

Purpose: To test the brain's reaction to oxytocin and vasopressin in pregnancy and lactation. Both hormones have vital roles during pregnancy, birth, and lactation. But their functions shift during these times, so the brain might react differently depending on the animal's status. Studying this in rats is supposed to allow conclusions on humans.

Source: Journal article

Year published: 2021

Summary: Half of a group of pregnant rats were injected to affect their babies' brain development. Some pups were allowed to grow up and put in plastic containers. Their calls to each other were recorded 10 times for 10min each.
We exposed an older paper using the same damaging technique in our 2021 12 Days of Christmas campaign.

Procedure: Twelve female rats were mated when they were 3 months old. On day 15 of their pregnancy, half of them were injected via a tail vein with a chemical that causes their immune system to respond strongly. This response is known to severely affect the babies' brain development. The other rats were only injected with a control solution. Three weeks after birth, the babies were taken from their mums. Some male babies from each mum were kept for the experiment. They remained in cages of two siblings each. It is not stated when the experiment occurred (around 3 months) or what happened to them afterwards.
To record their calls for comparison, two at a time were placed in a box with a divider between them. For 10 minutes, their communication was recorded with a microphone, and this was done ten times.

Purpose: To test the effect of maternal immune activation (MIA) on the social calls of rats. MIA is known to damage brain development during pregnancy. They hope for insights into the mental aspects of schizophrenia. Injecting rats with a substance to impair their pups is a standard method for schizophrenia research.

Source: Journal article

Year published: 2021